ABSTRACT

A COMPUTERIZED DIGITAL DATA ACQUISITION SYSTEM
FOR ELECTROCHEMICAL EXPERIMENTS

By

Joseph Samuel Cardarelli

A computerized digital data acquisition system is applied to
cyclic voltammetry studies for the elucidation cf electrolysis mechanisms.
To aid in understanding the computerized system, a general approach to
the interfacing of a digital computer to laboratory experiments is
presented. The basic logic gates, the interface components, and the
features of data transfer within the interface are discussed and a very
versatile interface which can be used to computerize virtually any
measurement performed in a chemical laboratory is described in detail.

To evaluate the efficacy of the computerized system for cyclic
voltammetry experiments, the reduction of a group of sulfonephthalein
indicators is investigated. The computerized system has resulted in
vastly improved data collection and analysis capabilities for cyclic

voltammetry experiments.

Finally, the interactive use of computer in the laboratory is

demonstrated by the computerization of classical polarography.

A COMPUTERIZED DIGITAL DATA ACQUISITION SYSTEM
FOR ELECTROCHEMICAL EXPERIMENTS

By

Joseph Samuel Cardarelli

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Chemistry

1971

ACKNOWLEDGMENTS

The author wishes to express his appreciation to Dr. Richard S.
Nicholson for his guidance and encouragement throughout this study.

The author is grateful to the Socony Mobil Oil Company, the
National Science Foundation, and the Department of Chemistry for
financial aid.

Special thanks go to the author's wife, Vibiana, for assistance
rendered throughout the course of his graduate studies.

Finally, the author wishes to express his appreciation to his
parents, Joseph and Julia Cardarelli, for making possible the attainment

of his education.

ii

TABLE OF CONTENTS

Page

I. INTRODUCTION ......................... l
A. Background ........................ l

B. Objectives and Contents of Thesis ............ 2

C. Description of the Minicomputer Employed ......... 3

II. BASIC LOGIC CIRCUITS ..................... 5
A. Binary Operations and Digital Logic ........... 5

B. Flip-Flops ........................ 5

C. The AND Gate ....................... 6

D. The NAND Gate ...................... 6

E. The OR Gate ....................... 9

F. The Inverting AND Gate ,,,,,,,,,,,,,,,,,, 9

G. The Inverter ....................... 9

H. More Complex Circuits and Functions ........... 9

l. The Device Selector .................. 18

2. The Bus Driver .................... 21

3. The Multiplexer ................... 21

4. The Analog-to-Digital (A/D) Converter ........ 21

5. The Digital-to-Analog (D/A) Converter ........ 29

III. INTERFACE AND INSTRUMENTATION ................ 33
A. Cyclic Voltammetry .................... 33

B. Requirements for the Interface .............. 37

C. Data Transfer with the PDP-B/I .............. 38

l. The Input/Output Skip Facility ............ 38

2. Transfer of Data by the PDP-B/I ........... 39

D. The Actual Interface ................... 40

E. Versatility of the Interface ............... 45

F. Analog Instrumentation .................. 46

G. Electrochemical Cell ................... 50

H. Chemicals ........................ 55

IV. CONTROL OF THE INTERFACE [IA_SOFTNARE ............ 56
A. The Role of Software ................... 56

8. Programming Minicomputers ................ 56

C. The Software Created for Cyclic Voltammetry ....... 6l

1. Basic Considerations ................. 61

2. Dynamic Scan Rate Range ............... 61

iii

3. Data Display ..................... 63
4. Background Corrections ................ 70 '
5. Data Analysis .................... 75
6. The Entire Software Package ............. 80
V. EVALUATION OF THE SYSTEM ................... 87
A. Introduction ....................... 87
8. Performance with a Dummy Cell .............. 87
C. Standard Chemical Systems ................. 88
1. Reduction of Cadmium ................. 88
2. Reduction of Thallium ................ 94
3. Reduction of Sulfonephtha1ein Indicators ....... 99
VI. COMPUTER CONTROLLED CLASSICAL POLAROGRAPHY .......... 106
A. Introduction ....................... 106
8. Classical Polarography and Possible Approaches ...... 106
1. Control and Acquisition of Data ........... 107
2. Data Display ..................... 113
3. Data Analysis .................... 114
C. The Software Package for Classical Polarography ..... 117
0. Discussion and Evaluation ................ ll7
VII. CONCLUSION .......................... 123
REFERENCES ............................. 124
APPENDICES ............................. 127
A. Logic Print of the Interface ............... 127
8. Software for Cyclic Voltammetry ............. 129

iv

LIST OF TABLES

Table Page
I Program Segment for Analog-to-Digital Conversion ...... 59
II Computer Output of Current versus Potential for Aqueous

CdSO4 in 0.10 Molar Na2504 at 20 Volts/second ........ 68
III Computer Output Illustrating the Disproportionation Rate

Constants for Five Sphericity Factors ........... 81
IV Example of Computer Teletype Dialogue ........... 86
V Sulfonephthalein Indicators ................ 101
VI Rate Constants of Sulfonephthalein Indicators ....... 105

VII Sample Teletype Listing During a Computer Controlled DME
Polarography Experiment .................. 121

LIST OF FIGURES

Figure
1. Symbol and truth table for the AND gate ...........
2. Symbol and truth table for the NAND gate ..........
3. Symbol and truth table for the OR gate ...........
4. Symbol and truth table for the Inverting AND gate ......
5. Symbol and truth table for the Inverter ...........
6. Basic elements of the device selector ............
7. Logic diagram for the Bus Driver ...............
8. Circuit diagram for the Multiplexer .............
9. Circuit diagram for successive approximations analog-to-
digital converter ......................
10. Circuit diagram for a digital-to-analog converter ......
lla. Variation of electrode potential with time for cyclic
voltammetry .........................
llb. Cyclic electrolysis current for reversible charge transfer. .
12. Block diagram of the programmed data transfer facilities of
the PDP-8/I .........................
13. Block diagram of the interface ...............
14. Circuit diagram of the instrument ..............
15. Photograph of outside panel of instrument ..........
16. Electrochemical cell ....................
l7. Illustration of the oscilloscopic display system ......
18. Illustration of the oscilloscopic display system ......
19. Charging current correction for a cyclic voltammogram . . . .
20. Blank data collected and displayed by the computer ......

vi

Page

8
11
13
15
17
19
23
25

28
32

35
35

42

49
52

74

21.

22.

23.

24.
25.

26.
27.

28.

29.

30.
31.
32.

Example of computer displayed diagnostic plot of
Ip/v 1/2 vs, 1n (v) .................... 77

Cyclic voltammogram illustrating locations of IC, the
cathodic peak current; IA, the anodic peak current; IS, the

switching current ..................... 79
Flowchart of DSEP, the main cyclic voltammetry program, and

K20, the disproportionation rate constant program ..... 83
Cyclic voltammogram for the reduction of cadmium ..... 90
Blank correction of cyclic voltammogram for the reduction

of cadmium ........................ 93
Cyclic voltammogram for the reduction of thallium ..... 96
Plot of computer diagnostic data for a cyclic voltammetry
experiment ........................ 98
Computer diagnostic plots for cyclic voltammetry experiments

of sulfonephthalein indicators .............. 104
Potentiostat for computer controlled classical

polarography ....................... 109
Effect of spurious noise on dme current ......... 112

Sample display of computer controlled dme polarography . . 116

Flow chart for computer controlled dme polarography . . . 119

vii

I. INTRODUCTION

A. Background

Although use of the so-called minicomputers in chemical laboratories
is still in the embryonic stage, it seems safe to predict that the
minicomputers are going to revolutionize nearly all chemical instrument-
ation. Indeed, there already are popular examples, such as Fourier
transform nmr and far-infrared Fourier transform spectroscopy, which
cogently attest to the truth of this statement.

Because of a strong conviction of the accuracy of the foregoing
remarks and this laboratory's interest in electrochemistry, this
thesis is devoted primarily to an electrochemical application of a
minicomputer. Although most of the work described herein is believed
to be original, this thesis by no means describes the first application
of minicomputers to electrochemical instrumentation. Indeed,
electrochemists were among the first chemists to use digital computers
in the laboratory, and therefore there already exists some electrochemical
literature in this area. Predictable, the first effort was by Glen
Booman, prior to the general availability of minicomputers (1). As
minicomputers became available at reasonable cost, several electrochemical
laboratories reported exploratory applications in on-line control of
experiments and acquisition, and analysis of data (2-8). In a
recent application (9) a minicomputer was used to overcome in real time
nonideal experimental conditions in stationary electrode polarographic
measurements. The computer was able to modify the course of the

l

2
experiment based on the nature of continuously monitored output. The
computer was programmed to interrupt the linear voltage sweep after
detection of each reduction step in order to dissipate the reducible
species in the diffusion layer and minimize interference with
succeeding reduction steps. This example, although fairly simple, is
a good illustration of the way a minicomputer can control an experiment

in an "intelligent" and interactive fashion.

8. Objectives and Contents of Thesis

A major objective of the research undertaken for this thesis
was to evaluate the efficacy of using a minicomputer for cyclic
voltammetry experiments, and elucidation of electrolysis mechanisms.
The hardware and software developed for this purpose are unique, and, as
will be shown, have resulted in some significant improvements in the
acquisition and interpretation of cyclic voltammetry data.

The first chapters of this thesis are devoted to the hardware
and software that have been developed, with the last chapters devoted
to chemical applications of the computerized system. Since computer
hardware, digital electronics, and interfaces are the essence of logic,
the average chemist, once provided with appropriate background material,
can easily understand the design and operation of a computer interface.
Because of this fact and a belief that in the future chemists will have
to possess some understanding of laboratory computers, Chapter II of this
thesis is devoted to topics necessary to equip the reader with the
background material required to understand the interface presented in
Chapter III. Chapter IV then deals with software (programming), first
illustrating how the interface can be controlled yia_software, and then
specifically describing the software that was written to perform the

cyclic voltammetry experiment. Chapter V is devoted to evaluation and

3
application of the computerized instrumentation to several chemical
systems. Finally, results of some preliminary studies of computer

controlled polarography are presented in Chapter VI.

C. Description of the Minicomputer Employed

Many minicomputers are now commercially available. In general,
each of these has different features and characteristics. Although
awareness of all of these nuances is not required to understand the
remainder of this thesis, it is appropriate to describe the most salient
features of the computer that was used.

The computer is a Digital Equipment Corporation Model PDP-8/I.
The PDP-8/I is general purpose computer using TTL (transistor -transistor-
logic) integrated circuit modules and parallel data transfer. The
PDP-8/I is organized into a central processor, a core memory, and input/
output equipment facilities (10). Word size is fixed at 12 bits
(binary digits), and core memory capacity for the machine used here
is 8192 words. The machine operates in the binary number system and
is capable of programmed arithmetic operations based on two's complement
operations. By convention, the 12 bits are used to represent directly
the numbers between -2048 and +2047. For expression of larger numbers,
two 12 bit storage locations (double precision) can be used to represent
directly the numbers between -8,388,608 and +8,388,607 or three 12
bit storage locations (triple precision or floating point) can be used
to represent numbers between 0.999999E-615 and 0.999999E+615. The
peripheral devices for the system used here include a teletype, a high
speed paper tape reader and punch, and a magnetic tape unit. The
computer's operations can be programmed either in machine language, a
mnemonic language, or a language such as FORTRAN. Bussed interface

connections to the central processor and various input/output features

4
are available for design of specific interfaces such as the one developed
here. Specific features of programmed data transfer in the PDP-8/I

used to develop this interface are described in Chapter III.

II. BASIC LOGIC CIRCUITS

A. Binary Operations and Digital Logic

The circuits and computer operations to be described are based
on the binary number system, which is a set containing two elements,
one (1) and zero (0). Sometimes these two elements also will be
referred to as high (1) and low (0), and in a logical sense (e.g.,
truth tables) high will correspond to "true" and low to “false". In
electronic circuits the two states can be represented in many ways, for
example a light on the console being on (1) or off (0), or a switch
being up or down. Within the computer the two states are most frequently
represented by voltage "levels", and in a computer with TTL circuits

(such as the PDP-8/I, vide supra) specifically by a positive voltage

 

greater than three volts gs, ground being high (binary l), and a
ground potential (< 0.2 V) being low (binary 0).

Although ideally suited for electronic circuitry, the binary
number system is often cumbersome to use in writing. Hence, other
systems are frequently employed as shorthand, and that procedure will
be adopted here, with subscripts to identify the modulus (e.g., 9 =

10
118 = 10012).

B. Flip-Flops

The so-called flip-flop is a common circuit element which possesses
the property of having only two stable output states - i.e., for TTL
circuits the output of a flip-flop is either +5 volts, or 0 volts.

5

6
Moreover, the output of a flip-flop can be caused to change states (or
"flip") by an appropriate signal (voltage) at its input.

These properties of the flip-flop make it a convenient device
for storing a single bit of information. Hence, a flip-flop can be set
to the high state (+5 V), and until intentionally changed will save that
binary 1 (remain at +5 V). Correspondingly, a set of twelve flip-flops
can be used together to represent a single 12-bit word of information -
for example, if all twelve flip-flops are set to the high state, they
will store the word (number) 111 111 111 1112 (= 77778 = 409510). In
fact, twelve such flip-flops constitute the memory element in the
accumulator of the central processor of the PDP-8/I (such a group of

flip-flops is often referred to as a register).

C. The AND Gate

 

The simplest digital logic circuit is the AND gate, so called
because it performs the electrical analog of the logical operator, AND.
Hence, the AND gate functions according to the truth table contained in
Figure l. The AND gate's output is low (0 or false) unless both of its
inputs are simultaneously high; then and only then is the output high
(1+ 3 V)-

The most commonly used symbol for the AND gate is shown in Figure 1.
Of course, it is possible for an AND gate to have many inputs; in that

case, the output is high if and only if all_of the inputs are high.

0. The NAND Gate
This acronym comes from Not ABE, and thus its operation is obvious:
the NAND's output is high unless all_inputs are simultaneously high, in which

case the output is low.

Figure 1. Symbol and truth table for the AND gate

 

 

 

 

 

 

AND GATE
INPUT OUTPUT
SIDE SIDE
A
F
B ——1
‘MINPUT OUTPUT,“
A B F
L L L
L H L
H L L
H H H

 

9
The truth table and common symbol for the NAND gate are given

in Figure 2.

E. The OR Gate

 

According to the truth table in Figure 3, the 0R gate's output
will be high if either or both inputs are high, otherwise the output is

low. The common symbol for the OR gate is also included in Figure 3.

F. The Inverting AND Gate

 

It can be noted from Figure 4 that the truth table for the so—called
inverting AND gate is identical to that for the OR, and therefore the
two circuits have identical logical functions. The common symbol for

the inverting AND gate is included in Figure 4.

G. The Inverter

 

The inverter circuit shown in Figure 5 is included here partly
for completeness, but also because it appears ubiquitously throughout
the interface. The inverter's output is simply the opposite of its

input.

H. More Complex Circuits and Functions

 

The basic elements above can be used in combination to provide
the necessary control and communication between the experiment and computer
that constitute the interface. Although in general each interface is
unique to a given situation or application, some subsections are common
to nearly all interfaces. Thus, to understand the interface described
in the next chapter, it also is necessary to understand some of these
more complex building blocks, such as digital-to-analog converters

and device selectors.

10

Figure 2. Symbol and truth table for the NAND gate

ll

NAND GATE

INPUT OUTPUT
SIDE SIDE

 

 

 

 

 

INPUT OUTPUT

I I I" I" D
I I" I l"
l" I I I ‘11

 

12

Figure 3. Symbol and truth table for the OR gate

13

OR GATE

 

 

INPUT OUTPUT
SHDE SIDE
A
F
5
INPUT OUTPUT
A a F
L L L
L H H
H L H
H H H

 

14

Figure 4. Symbol and truth table for the Inverting AND gate

15

INVERTWNG

 

 

 

AND GATE
INPUT OUTPUT
SHOE SIDE
A—o
F
B__*43
INPUT OUTPUT

 

I I I" I" D
I I" I I"
I I I I" '71

 

16

Figure 5. Symbol and truth table for the Inverter

17

INVERTER

 

 

 

INPUT OUTPUT
EHDE EHDE
A.___{) F
INPUT OUTPUT
A F
L

; H

 

18

l. The Device Selector. To function usefully the computer must

 

be able to communicate with several so-called peripheral devices (the
experiment, the teletype, etc.). The only means of communication for a
computer is by voltage pulses (so~called input-output pulses, or simply
IOP pulses), and therefore some method must be used to insure that an
IOP pulse reaches only a single device (e,g,, the teletype, but not the
experiment). The feat is accomplished readily with an interface element
called the device selector.

Each peripheral device is identified by a unique six-bit code

(note, therefore, one can have 26

or 64 different peripheral devices)
and, when communication is desired, the program places this six-bit
code in a special register (six flip-flops referred to as the memory
buffer register). In essence, the device selector decodes the contents
of this register, and routes an IOP only to the peripheral device that
was coded. (Greater details of this operation are given in Chapters III
and IV.)

The basic elements of the device selector are shown in Figure 6.
The gate, G1, is an AND gate, and therefore the output is high only when
all six inputs are high. Thus, hardwire connections are made from the
memory buffer register (and its complement which is simultaneously
available), so that the six inputs to 61 correspond uniquely to the
peripheral whose code appears in the memory buffer. The output of G1
is sampled by the NAND gates, 62, G3, and G4, and compared to the source
of IOP pulses within the computer. In the event that an IOP pulse has
been generated at the same time the proper code appears at the input of
GI, an output pulse (just like an IOP, but now involving an input-output

transfer, and therefore called an IOT) appears at the output of the NAND

19

Lopumpmm m0w>mv as» we mucwsm_w uwmwm

.m mczmwm

20

 

 

 

 

 

 

3
.ATHADIJ mac.
5 .
no
m .8.
mo
, 8
t9 - l0.
3

 

 

Epsom 4mm MQSMQ

NI.”
/1

llllII

 

21

gate. [The POP-8/I can generate three different IOP's and therefore
the device selector shown in Figure 7 contains three NAND gates.
Inverters are included on the output of the NAND gates so that the
interface designer has both the IOT and its complement at his disposal.]

In summary, if, for example, 000 0012 (code for the teletype)
appears in the memory buffer register flip-flops at the same time that
the computer generates an IOP, then an IOT reaches the teletype (causing
it to type a character, for example), but no IOT's reach any of the other

peripheral devices.

2. The Bus Driver. Another common interface element which is

 

referred to as the bus driver, is shown in Figure 7. This device is
used to transfer data in parallel - 1,g,, 12 bits simultaneously. Since
in the PDP-8/I a word is 12 bits, the bus driver consists of twelve
inverting AND gates whose outputs are low when both inputs are low. By
hardwiring one input in common between all twelve gates (see Figure 7) a
data transfer results whenever this common or enable input goes from
high to low (+3 V to ground). (The bus driver is also known as a signal

gate.)

3. The Multiplexer. The multiplexer depicted in Figure 8 is

 

simply a single pole, four position switch that can be operated
electronically. The switches (basically FET transistors) are connected
to a series of AND gates, so that coded inputs to the AND gates can be
used to select uniquely the "switch position". The multiplexer shown in

Figure 8 is used to switch analog signals into the A/D converter.

4. The Analog-tO-Digital (A/D) Converter. The use of transducers
is commonplace in the chemical laboratory. The standard transducers are

devices that convert some property (temperature, pH, etc.) to a proportional

22

Figure 7. Logic diagram for the Bus Driver

24

wampgwp_:z mcp Lo; Emcmmwu uwzogwo

.m wczmwm

26
voltage which can in turn be read, plotted, etc. To make a digital
computer a useful laboratory instrument a similar transformation is
needed, namely the conversion of voltages (derived, for example, from
the above transducers) into a digital equivalent. [In this case the
term digital equivalent means a set of twelve flip-flops whose outputs of
+3 V or O V correspond to the numerical equivalent of the input voltages.]
The device which accomplishes this conversion is called an analog-to-
digital converter. (Some transducers such as photomultiplier tubes and
geiger tubes may already produce a digital output and thus will not
require analog-digital conversion.)

Since A/D converters are common to nearly every laboratory interface,
it may be useful to describe briefly the way in which an A/D converter
works. Actually there are many approaches to A/D conversion, and therefore
only the successive approximations type used for this research will be
described (Pastoriza, Model ADC 12 U, see Figure 9).

A/D conversion by successive approximations is exactly analogous
to weighing an object with a series of standard weights on an analytical
balance. Thus, for a twelve bit A/D converter, twelve standard voltages
are generated internally with precision resistors and then switched
sequentially into the comparison amplifier, which also receives the input
voltage (see Figure 9). The output of the comparison amplifier determines
whether the reference voltage is greater or less than the input voltage,
and thereby determines whether a given weighing voltage is left connected.
The first comparison involves the largest standard reference voltage, and
therefore corresponds to the most significant bit. Each succeeding
reference voltage is then tested with the corresponding bit set high
if the reference voltage is less than the input voltage, and set low if

the reference voltage is greater than the input voltage. Since each of

27

3 NF uo< ~mnoe mNPLoumma .meLm>coo

quwmvaop-mochm mcowumewxocaam m>wmmmou=m com Emmewu uwzucwu

.m acamwm

28

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

29»on 2.8.. T0
E «3.58 85:03 Tlloz<zzoo
- H H H h¢U>ZOO
— «do: I 24...
— 92 3:3
JOKPZOO mmd mm:
mmcmhm N. IIIIIIIIII N _
. I H I
4.
.m!< £200
FDA—z.
2253 8.2.2 ,

 

 

mmbmm>zoo 4<h55u904<2<
20:<2.xomlm< mimmmooam.

29

the reference voltages differs by a factor of precisely two, the result
of this operation is a twelve bit numerical equivalent of the input
voltage. The A/D converter used in this study has a relative accuracy
of :_0.0125% (jj/Z least significant bit), a differential linearity of
jfl/Z least significant bit, and a conversion time of 10 microseconds.

Most commercial A/D converters include several other standard
features in addition to those just described. For example, a conversion
is initiated only when a +3 V pulse (for TTL) is received by the A/D
converter (which normally is an IOT derived from the device selector
assigned to the A/D converter). The A/D converters also include a so-
called "flag" which is "raised" when the A/D conversion is completed.
The flag is simply an output connection that is gated from 0 to +3 V
when the conversion is finished. The computer, of course, can sense this
change, and thus be "advised" when the conversion is completed. The

importance of this feature will become apparent later.

5. The Digital-to-Analog (D/A) Converter. Naturally, the D/A

 

converter performs exactly the reverse Operation of the A/D converter
just described. Thus, the D/A converter will take a twelve bit number

in the computer and convert it to the analogous (or analog) voltage.
Probably the most obvious use of this operation is plotting of data stored
in the computer by connecting the output of the D/A to an oscilloscope

or conventional recorder. There are, of course, many other possible

uses of a D/A which make it an important part of many interfaces. These
include generation of control voltages (such as the waveform for an
electrochemical experiment - see Chapter VI and References 11 and 12)
control of solenoids, relays, valves, motors, etc. Indeed, it is usually
via_D/A converters that a computer can be used as an instrument in a

truly interactive manner.

30

The D/A converters used in this study are of the precision ladder
resistor design (Datel DAC VR 128 1B), which is illustrated in Figure 10.
The D/A converter consists of the resistor network, in addition to high
speed offset-free electronic switches, an internally mounted temperature
compensated reference source, and reference and output amplifiers. An
input storage register is available for accepting and storing the digital
data prior to conversion. When enabled by an IOT, the digital data are
transferred into the logic gates which change the status of the electronic
switches with the associated ladder network. Currents are then switched
into the output amplifier which converts these currents into a voltage
representative of the digital input word. The D/A converters used in
this study have an absolute accuracy of :0.01% of full scale (jj/Z
least significant bit), an output settling time of less than 2 microseconds,
a resolution of :1 least significant bit, and a linearity of :1/2

least significant bit.

31

m F m_ m> o<o Pmuos —mumo

.mecw>coo mopmcmiopIFmpwmvu a Low Emcmmwu pwzucwu

.o_ at=mea

32

(Xena! 4:53 /

\ I

 

 

 

 

 

 

 

 

 

 

 

wto «to :8
I Paaz_
5.559. 33.85 5.2. uncut."
ozaoco
3.2.2 — I 326 23.. , I
Pampao 1* r
3.2;: Wo. ............
.2. _
I x5352 585 2298.5 I
_Iuo§om I
wozucmumx-

 

Kuhmm>zoo 00.326, I 43:65

III. INTERFACE AND INSTRUMENTATION

This chapter deals with the interface that was designed to provide
data transfer and general two-way communication between the experiment and
the computer. In designing the interface, the primary consideration was,
of course, computerization of cyclic voltammetry; a secondary consideration,
however, was to have the interface be of such general utility that other
techniques could be computerized merely by changes in software (cf.

Chapter IV) rather than changes in hardware. To understand the requirements
of cyclic voltammetry, some familiarity with the technique is naturally
required. Hence, for the sake of completeness, a brief description of
cyclic voltammetry will be given prior to discussion of the interface

itself.

A. Cyclic Voltammetry

Basically, cyclic voltammetry involves recording current at a stationary
electrode as a function of an imposed potential that varies as a triangular
wave (see Figure 11a). Consider a substance, 0, that can be reduced
electrolytically to R; further assume that this reaction is reversible,
and that the standard potential is E°. Then, at the beginning of a
cyclic voltammetry experiment (t = O), the stationary electrode is initially
at a potential, g1, which is very anodic of E3, so that no reduction of
O to R occurs. Next, the potential is caused to vary linearly with time
in a negative (reducing) direction. At time t_= A (cf. Figure 11), the
direction of the linear scan is reversed (the rate of change of potential,
2, is held constant).

33

34

Figure 11a. Variation of electrode potential with time for cyclic

voltammetry

Figure llb. Cyclic electrolysis current for reversible charge transfer

EIi)

Current

Electrolysis

35

 

 

 

i=0 fax tszx

 

 

 

120 60 0 -60
n(E-E°)
Figure llb

36

Figure llb shows the variation of electrolysis current during the
course of the potential variations just described. During the first leg
of the triangle electrolysis current increases from zero, reaches a
maximum (peak) and then decreases, this decrease resulting from depletion
of O in the vicinity of the stationary electrode. Next, during the
second leg of the triangle, the stationary electrode becomes more oxidizing,
and consequently the R formed near the electrode is oxidized back to the
starting material, 0. The current for the R_+ Q_portion of the current
potential curve exhibits a minimum for reasons analogous to those described
above for the cathodic maximum.

In reality, Of course, most electrolyses are not as simple as the
one discussed in connection with Figure 11. The most common complications
are involvement of 0 or R (or both) in chemical reactions. For example,
experiments described later in this thesis involve systems where the
initially formed product of electron transfer (R) is chemically unstable,
and spontaneously disproportionates. This complication leads to enhancement
of the cathodic (reduction) peak current and simultaneous diminution of
the anodic (oxidation) current. An extremely important feature of cyclic
voltammetry is that complications such as these are easily and systematically
detectable. There are basically three reasons for this. First, the
experiment permits direct observation of both reactants and products
(cf. polarography, where in general only reactants are observed directly).
Second, the rate of voltage scan, 3, or really the duration of the experiment,
can be varied over a wide dynamic range (ca. six orders of magnitude).
This means, for example, that curves can be recorded in times much less
than, comparable to, or much greater than the half-life of many coupled
chemical reactions (such as disproportionation, vide supra). And third,

theory for cyclic voltammetry has provided guidelines for the systematic

37
analysis and interpretation of cyclic data obtained with large ranges of
scan rates. For example, one of these so-called diagnostic criteria (13)
involves a plot of peak current divided by the square root of scan rate
1;, scan rate. In this case deviations from a horizontal line are
indicative of chemical complications, and the morphology of the deviations
is predictive of the exact type of complication (13). Hence, of the
modern electrochemical techniques cyclic voltammetry is among the most
useful and widely employed, and for these reasons the one on which this
thesis focuses. More comprehensive discussions of cyclic voltammetry are

available in the literature (13-53).

B. Reguirements for the Interface

 

The minimum requirements are that the computer be able to:
(l) recognize (or cause) the start of a cyclic voltammetry experiment;
(2) digitize and store values of cell current and potential; (3) operate
for a wide and arbitrary range of scan rates; and (4) display the
collected data rapidly and in convenient form. Of course, once stored in
the computer a number of calculations can be performed on the experimental
data.

Based on these requirements, it is clear that the interface must
include an A/D converter, and since at least two variables need to be
digitized, the input to the A/D must be multiplexed (cf. II.H.3). [In
principle two A/D converters could be used, but in practice that is
seldom done since A/D converters are expensive compared with multiplexers.]
Also, D/A converters that permit plotting of data stored in the computer's
memory will be required. Finally, the interface must provide for
controlled twg:_ay_transfer of data and information. These data
transfers are described next, followed by a description of the actual

interface.

38
C. Data Transfer with the POP-811

 

In general, three types of communication are required. The
computer must be able to request a peripheral device to begin performing,
the peripheral must be able to tell the computer when it has finished
its task, and data (i.e., twelve bit words) have to be transferred
(i.e., from peripheral to computer, and vice versa). The communication
of commands from the computer to a peripheral already has been described
in connection with the device selector (cf. II. H. 1). Communication of
the peripheral's status involves use Of a skip facility, which is

described next.

1. The Input/Output Skip Facility. In general, the computer can
service (or be serviced by) only one peripheral at a time. Since
execution of computer operation is usually very rapid (of the order of
microseconds) compared with operation of a peripheral (of the order of
seconds for a teletype), it is essential that the computer be informed
when a peripheral has completed its task. Thus, each peripheral has a
so-called busy/done flag (actually a flip-flop), which is in one logic
state (low) during its operation, and the opposite logic state (high, or
"the flag is up") when the operation is completed. The computer makes
use of this flag yja_the skip facility. 0n the PDP-8/I this skip is a
bus (connection) which, if driven to ground, will cause the computer to
skip unconditionally the next instruction encountered in the current
program sequence. This feature permits the testing of a peripheral's
status as follows. First, the peripheral's busy/done flag is connected
to one input of a NAND gate, whose output is connected to the skip bus.
The other input of this NAND is connected to the output of a device

selector (and hence to an IOT whenever the particular device's code

39
appears in the memory buffer register and a computer IOP is generated -

see discussion under II. H. 1.). The program sequence is as follows:

1. Check the peripheral's flag and skip if it is up
2. Go back one instruction

3. Continue with the program

During instruction 1, an IOT reaches the input of the NAND gate referred
to above, but the output of the NAND gate stays high if the peripheral
device has ggt_comp1eted its operation (its flag is down, or low).
Hence, the computer moves on to instruction 2, which quickly (in about
1.5 microseconds) sends it back to check the peripheral's status flag
again. If this time the flag is up (high) when an IOT from the device
selector again reaches the other input of the NAND, the output goes low,
driving the skip bus to ground, and causing the next instruction to be
skipped. Since the next instruction is 2, the program gets out of its
tight check loop, knowing that the peripheral has completed its task,
and the computer is free to communicate with other peripherals.

The final type of communication referred to above is the two-way

transfer Of data, or words; this topic is discussed below.

2. Transfer of Data by the PDP-8/I. Computer controlled data

 

transfers all take place through the special twelve bit register called

the accumulator. The reason for this is that under program control,

40
data can be brought from the core memory to the accumulator, and similarly
a word in the accumulator can be stored in core memory. Hence, for example,
if the result of an A/D conversion can be placed in the accumulator, as a
twelve bit word, then this datum can be transferred under program (software)
control to core and saved. The interface, then, must accomodate the step
involving transfer of the word from the A/D to the accumulator. This
transfer is achieved as follows. The outputs of the A/D are connected
through a set of level converters (inverters — see II. G.) to the input of
the bus driver described earlier (II. H. 2.). Then, just prior to data
transfer the accumulator is cleared (all twelve flip-flops are set to zero,
or low, 113_a microinstruction - see discussion in Chapter IV). The so-called

accumulator input bus will now transfer a logic level one to the accumulator

 

whenever the corresponding accumulator input bus connection is driven to
ground. Thus, if the enable input of the bus driver is made low by an IOT
from the appropriate device selector, all other low bus driver inputs
(recall the presence Of the inverters) will result in binary ones being
transferred to the accumulator. High inputs to the bus driver during this
operation result in zeros being transferred to the accumulator.

For data transfer from the accumulator to a peripheral (such as a
D/A converter), the desired word from core is placed in the accumulator
(yja_software - see Chapter IV), and then, by essentially the reverse Of
the above process, transferred to the peripheral.

The three types of communication just described are summarized

pictorially in Figure 12.

D. The Actual Interface

 

The actual interface that was finally designed for cyclic voltammetry
is shown as a block diagram in Figure 13; a detailed logic print of the

interface constitutes Appendix A of this thesis.

41

H\m-aoa mcp yo mmwpwfiwomm cmmmcmcp mumn umEEmLmoca mcu mo EMLmen xOOFm

.N_ ULSSLL

42

 

     

>._._..=o<m
hunccuhz.

hmuaawc

 

 

 

 

 

 

 

 

 

 

 

Paaccuhz_ a<¢oo¢a
a<¢oo¢a
53.03. a...»
Paapao
as.» -53:
<53 5...: 55.3,.
«.5233
<P<o knapao
A o-»
aim who :3
._ .8
55523 A I I I :6
umbaa cuooouo .
"F Panhao thmaum CUPm_Ow¢
ao. .. Saz. 20.53.52. 20:35:.

 

 

 

 

 

   

 

"aha-aux
muuuao

>¢02u2

 

 

>102w3
ucoo

 

 

~\m QQQ thWZth $36 QMEEQQOOQQ

 

 

43

mommLmHCw any we Emcmmwu xoopm

.m_ mesmem

44

 

 

 

 

 

3.5.. 2325. :2...» 35323
]

3......238 .33 3.32....

I 9.4

h<hm2hzuhoc

 

 

 

    

 

Kuhcu>zou ghoudum
44:05 493.55
00.3.: uquAFJDI

I .533... .33 .
.33 a
33.238583

_ aunwufiuhu >333
388.. .88

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

333 .8033 8333 . .
333 353 353
I I \ E‘
Z . . _ _ _ . - . \r
3.4“”: $3.2... 32523 3......- flan“:
£53258... .53 .3. :33: 3.2.5280

.:_.I rfl : _, _

:8: caulztc<

 

dF¢u>28 -H¢u>200

004<z< $044.:
4(205 45:93

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     

 

 

 

 

- - a: 3:3 :2:
Ta » 3.2..
< 38 35.3.8 .258

 

35-0031

 

 

 

 

MOSEQMHZ‘ k0 IQQQSQ XOOAQ

45

Figure 13 should be readily understandable in light of the
preceeding discussions (the cell, potentiostat and function generator
are described in detail later - IV. E.). Nevertheless, it may be useful
to describe briefly the overall operation of the interface.

Initially, the computer program is operating in a tight two
instruction loop of the type described above (IV. C. 1.): (1) check the
potentiostat's flag and skip the next instruction only if it is up; and
(2) jump back one instruction in the program. The instant the triangular
wave scan is begun, the potentiostat "raises" this flag, and the computer
"escapes" from the above loop and begins the data collection operations.
These involve setting the multiplexer to the current or potential
positions, requesting an A/D conversion, checking the status flag Of the
A/D, and transferring the data vja_the bus driver into the accumulator.
When the experiment is completed, the collected data can be inspected
quickly from an oscilloscope plot yja_the two D/A converters. Processing
of the data, which also occurs during and after the above operations, is

discussed in Chapter IV.

E. Versatility of the Interface

 

Before leaving the discussion of the interface, the reader should
realize that the versatility, which was a secondary Objective in designing
the interface, was actually achieved. Thus, voltages of any origin, not
just electrochemical, can be attached to the multiplexer inputs, digitized,
stored, processed, displayed, etc. Hence, the computer and interface
described in detail here can be used directly to computerize virtually
any measurement performed in a chemical laboratory. The electrochemical
techniques already studied with this interface include cyclic voltammetry,

polarography, and coulostatic studies. Moreover, voltages from the

46
D/A's can not only plot data, but can be used to control experiments (see
Chapter VI) and Operate other devices, so that this interface permits

operation in a truly interactive fashion.

F. Analog Instrumentation

A solid state instrument with a combined function generator,
potentiostat, and power supply was constructed to perform the cyclic
voltammetry experiments. The instrument was built to provide capability
for fast scan experiments; an effort was made to develop a versatile
instrument, yet one that was simple to Operate. Versatility was achieved
by having the function generator capable of ramp and hold experiments,
single cycle triangular wave with variable hold potentials, and multicycle
triangular waves. In addition, the initial potential, the cathodic and
anodic limit potentials, and the hold potentials are all independently
variable. The rate of voltage scan can also be independently varied from
polarographic values of a few millivolts per second to one thousand
volts per second. Also included in the potentiostat is an IR compensator
which corrects electronically ng_positive feedback for IR drop in the
electrochemical cell.

The instrument also was designed specifically for simple operation.
Thus, a single master function switch allows direct setting of ramp and
hold, single cycle, or free running experiments. The scan rate can be
directly set from a single range switch and a direct digital potentiometer.
Both cathodic and anodic limit potentials, the hold potential, and the
initial potential can be directly set with digital potentiometers.
Current sensitivity is set with a direct reading Dekastat which is in
the feedback loop of the operational amplifier in the current follower

configuration (see Figure 14). To operate the instrument, a switch to

Figure 14.

47

Circuit diagram of the instrument

VF
CF

voltage follower

current follower

control amplifier

current boosters

low voltage power supplies
half of MC1435F (Motorola)
Analog Devices 111

GPS F0-201 follower
Analog Devices 147A

Texas Instruments SN747O
Sylvania 1N464

Schauer $2 3.0

Sylvania 1N464

Texas Instruments 2N2368
MP5 6517

Fairchild F3Nl49

Fairchild F3Nl49

Analog Devices 111

Analog Devices 146

10 KA, 5%

1 KA, ten turn potentiometer
1 KA, trim pot

100 KA, 1%

10 KA, 1%

100 KA, ten turn potentiometer

10 MA, 1%

RIO

R
11

R12
RI3
R14
R15’ R16
R17

R18’ R19
“20’ R21’ R23
R25’ R25

48

1 MA, 1%

1 KA, 1%

10 KA, 5%

1 KA, 5%

3 KA, 5%

1O KA,1%

Dekastat

1 KA, 1%

50 KA, 0.1%

50 KA, 0.1%

500 KA, 0.1%

5 KA, 0.1%

0.001, 0.01, 0.1, 1.0, 10 ufd
5 POL-6 P05

3 POL-6 POS

l POL-3 POS

SPDT

DPDT, momentary contact
Counter electrode
Reference electrode

Working electrode

49

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

50
determine whether the scan will be cathodic or anodic is first activated.
Then, at the start of the scan, a trigger pulse is provided for either
triggering an oscilloscope or indicating to the computer that the
experiment has begun. Output for the instrument is available as cell
current (the voltage of the current follower divided by the load
resistor) and the cell potential. The two signals are multiplexed into
the analog-digital converter for computer monitoring of the experiment.

All components except for the potentiometers and switches were
mounted on four 3" X 5" printed circuit boards. Standard Operational
amplifier circuits were used for the integrator, the control amplifier
of the potentiostat, and the current follower (54-57). A combination
Of integrated circuit Operational amplifiers, switching transistors,
and flip-flops was used for the function generator. All of the front
panel potentiometers can be calibrated within one percent of the
reading with the aid of trim potentiometers located in the rear of the
instrument. A detailed circuit diagram is given in Figure 14, and a
photograph of the instrument, which has operated satisfactorially for

two years, is shown in Figure 15.

G. Electrochemical Cell

The electrochemical cell, which is shown in Figure 16, consists
of a glass weighing bottle with a 60/12 joint on the top. The cell lid
is made of teflon and machined to fit this joint. Holes were drilled
through the lid to allow insertion of the various cell components
(Figure 16). The counter electrode was either a platinum wire wound
around a teflon rod or a single graphite rod. The reference electrode
contained three separate sections separated by fine fritted glass discs.
The lefthand compartment was a saturated calomel electrode and the

right hand compartment contained the solution being investigated. The

51

“amazcumcw we —m:oa muwmuao mo camcmouogm

.m. aL=S..

52

 

 

 

Figure 16.

53

Electrochemical cell

A:
B:

Reference electrode

Scoop

Hanging mercury drop electrode
DrOpping mercury electrode
Deaerator

Counter electrode

54

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

F .9?
E .IIIIHHu
0m ..
c H v.
BnIIHHI
”AIIJ a
II.“
\
III. E
C
s

 

 

 

 

 

 

 

 

55
center compartment contained one molar sodium nitrate. The right hand
compartment of the reference electrode could be disassembled at the
14/20 joint to allow a tube closed with a fritted disc to be inserted
into the solution. The stationary mercury electrode was constructed
according to the procedure of Ross, Demars, and Shain (58). Generally
one drop from the dropping mercury electrode was collected in a scoop
and suspended from the working electrode. The deaerator was of conventional
design and could be raised above the solution to provide a nitrogen
blanket over the solution while measurements were being taken. All

measurements were made at an ambient temperature of 23-24°C.

H. Chemicals

Aldrich reagents bromocresol purple, phenol red, bromopyrogallol
red, and Matheson Coleman reagent chloro phenol red were used without
further purification. The solvent was 25% (by weight) methanol-water
with a supporting electrolyte of a 0.1 molar citrate buffer of pH 4.8.
The pH was adjusted by adding NaOH until the desired pH was indicated
on a standardized pH meter. For the other experiments, Fisher reagent
grade thallium nitrate, cadmium sulfate, potassium chloride, and sodium
sulfate were used without further purification. For use as a maximum

suppressor, a 0.003% gelatin concentration in the solution was prepared.

IV. CONTROL OF THE INTERFACE VIA SOFTWARE

A. The Role of Software

The versatility of the interface described in the previous
chapter is achieved by computer programming, or the so-called software.
Indeed, it is actually the software that determines whether the inter-
face is used to control an experiment in chromatography or electro-
chemistry. The following discussion will illustrate this fact, and in
particular will illustrate how program instructions are used to select
peripherals and control the flow of information and data between the

experiment and the computer.

8. Programming Minicomputers

The instructions that control an interface are normally written
in an assembly language which uses a mnemonic to represent an actual
binary instruction (e.g., HLT, the mnemonic for "halt execution" is
much more convenient for programming than 111 100 000 0102, the actual
binary instruction that the computer is wired to interpret as halt).
Therefore, assembly language has a one-to-one correspondence with the
true machine language (binary numbers) that the computer “understands",
and sometimes assembly language is referred to (incorrectly) as machine
language. Again, the PDP-8/I is typical of minicomputers, and therefore
it is profitable to explain how programs control data collection.

With the PDP-8/I the first three bits (called the operation code)
of a twelve bit word are used to identify instructions in the computer's
repertoire. There are eight unique combinations for these bits

56

57
(000, 010, 011, etc.). and therefore the PDP-8/I has eight basic
instructions in its repertoire. These instructions or operations fall
in three groups: (1) memory reference instructions; (2) operate
microinstructions; and (3) input-output transfer instructions.

There are six (0002 to 1012) memory reference instructions all
of which involve explicit addresses of core memory locations. For
example, if the first three bits of an instruction are 1012 (58), then
the computer is wired to transfer control unconditionally to a memory
location identified by the remaining nine bits in the word. In assembly
language this would be written as JMP (for "jump" or transfer control
unconditionally) followed by a mnemonic indicating the desired memory
location.

A microinstruction is indicated by 1112 (73) in the first three
bits. The microinstructions operate on the remaining nine bits by
further decoding them (hence, the name microinstruction) into operations
involving only the accumulator (never memory or input-output). Thus,
microinstructions all begin with 78, and provide the control instructions
such as halt (111 100 000 0102 = 74028, assembly language mnemonic is
HLT), set the twelve bit accumulator register to zero (111 010 000
0002 = 72008, mnemonic is CLA for "clear the accumulator"), skip the
next instruction if the accumulator is zero (111 100 100 0002 =
74408, mnemonic is SZA for "skip on zero accumulator"), etc.

The third class of basic instructions is the input-output
transfers (IOT) referred to earlier in connection with the operation of
the A/D converter. An IOT instruction is always indicated by operation
code 1102 (68) in the first three bits of an instruction in the memory
buffer. The next six bits identify the peripheral device with which
communication is desired and the last three bits indicate which of

several IOP's is to be generated. Schematically, a twelve bit IOT

58

instruction takes the form

1 l O 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0
op. code. device code code for IOP
68 indicating IOT OO8 - 778 18 - 78

The formation of an IOT instruction is best illustrated with a
specific example, such as performing an analog-digital conversion.

For the interface described earlier, the A/D converter was called
device 538 (4310), by appropriately hard-wiring a device selector
between the memory buffer in the computer and the A/D converter (see
discussion II. H. 1.).

The device selector was further wired so that only IOP number
two would activate the A/D converter. Hence, the machine language
instruction (or word) that activates the A/D converter would be 68
(operation code for IOT telling the computer that an IOP is needed)
followed by 538 to activate the A/D converter's device selector,
followed by 28 to generate IOP number two. The mnemonic adapted for
this instruction was ADCV (for analog-to-digital convert), so that the
assembly language compiler on encountering "ADCV" in an assembly language
program will automatically replace ADCV by the binary machine language
instruction 110 101 011 0102 (= 65328).

With this background, it is possible to illustrate the entire
operation of data collection under program control. A possible program
segment [beginning arbitrarily in memory location 000 010 000 0002
(02008)] is shown in Table 1. After execution of the first instruction
(CLA, or clear accumulator), all accumulator registers are set to zero
(this is necessary for the data transfer as described in Section III. C.
Next, the computer encounters the instruction 65418, which will result

in an IOT (because of operation code 68) number one reaching the device

Table I.

Program Segment for Analog-to-Digital Conversion

 

 

 

Octal Octal
Location Mnemonic Code Operation
0200 CLA 7200 Clear the accumulator (prevent any
logical combination of the results
of the A/D conversion with a
number already residing in the
accumulator)
0201 SCl 6541 Set channel one of the multiplexer
through which analog signal is
presented to A/D
0202 ADCV 6532 Convert command presented to A/D
0203 ADSF 6531 Skip on A/D flag (wait for completion
of conversion)
0204 JMP .-l 5203 Jump back one instruction (continue
searching for flag)
0205 ADRB 6534 Read A/D buffer results into

accumulator

 

60

called 548 (= 4410). For this interface device 548 is the multiplexer
(see II. H. 3.), and the appropriate device selector was wired so that
IOT number one activates only the first position of the multiplexer
switch. Hence, instruction 65418 was given the mnemonic SC1, representing
"set channel one" on the multiplexer. Thus, after execution of this
instruction, channel one is open, so that any external signal connected
to channel one is now also connected directly to the input of the A/D
converter (see Figure 13).

The next instruction in Table I is the ADCV described above.
After execution of ADCV, the A/D converter begins the process of converting
the signal on channel one of the multiplexer into a twelve bit word.
Next, the computer encounters 65318 which generates IOT number one from
the device selector which had been assigned selection code 538. This
IOT one is gated into a NAND gate with the A/D converter's busy/done
flag. The output of the NAND gate is wired into the computer's skip
facility described earlier (see III. C. 1.). Thus, as explained above
(III. C. 1.), if the flag on the A/D converter is up the next instruction
is skipped, whereas if the flag is down the next instruction is executed.
In this case the next instruction is 52038, or jump unconditionally to
memory location 2038 (see discussion of memory reference instructions).
The assembly language mnemonic here is JMP .-1, which translates as
"jump back one instruction". Thus, the computer stays in this two
instruction loop (between locations 2038 and 2048) until the A/D
conversion is completed (about 10 microseconds). At this point, the
program reacheslocation 2058 where it encounters another IOT instruction
(65348) which generates IOT number four from device selector 538'
The interface is wired so that IOT number four from device selector 53

enables the bus driver described above (II. H. 2.), causing transfer

61
of the results of the A/D conversion directly into the accumulator
(which had been cleared previously). At this point the piece of data,
which is simply the voltage on channel one over a time window of about
10 microseconds, could be saved (stored in core or on magnetic tape or
punched tape), further processed (multiplied by a numerical constant for
normalization, added to a running sum for time averaging, etc.). listed

on the teletype, or displayed graphically.
C. The Software Created for Cyclic Voltammetry

1. Basic Considerations. In developing the software for cyclic
voltammetry several features were considered to be desirable. The most
general consideration was that the computerized system possess maximum
convenience and versatility. Thus, the system should not require
detailed familiarity with the computer or its operation; or in other
words, options and control should take place through communication with
the computer in English ng_the teletype. With this general guideline
in mind several other features peculiar to cyclic voltammetry were
considered desirable:

(a) a large dynamic range Of scan rates over which experimental
data could be collected;

(b) immediate display of the data;

(c) convenient correction of the experimental data for charging
current and background effects; and

(d) options of data analysis for mechanism elucidation and

determination of rate constants.

2. Dynamic Scan Rate Range. Since cyclic voltammetry experiments

are performed over a very wide range of scan rates (ca., 10 mV/sec to

62

perhaps 1000 V/sec - see discussion III.A.), the computer must be able
to provide internal timing between the A/D conversions and acquisition.
Fortunately, this is easily accomplished since the PDP-8/I (as well as
most computers) contains a "clock" (actually an oscillator of precisely
known frequency) that can be used to provide accurately timed delays
between operations. The size of the delay is determined by the scan
rate to be used and the desired resolution - i.e., how frequently in
terms of applied voltage the current is to be measured. For example.
at a scan rate of 1.0 V/sec with a point collected every 10 mV, one
A/D conversion must be made every 10 milliseconds.

In practice, the system works as follows. At the beginning of
an experiment the computer requests via_the teletype the values of scan
rate and resolution to be used. The Operator then responds by typing
these numbers on the teletype. The computer next divides this resolution
by the scan rate to determine the appropriate delay between A/D
conversions. The computer uses this number (in seconds) with the known
frequency of the clock to calculate the actual binary delay constant
to be loaded into the clock counter to provide the necessary delay.

With this approach there is virtually no lower limit to the
scan rate that can be used (other than the natural one imposed by the
experiment itself). There is, of course, an upper limit determined by
the maximum rate at which an A/D conversion can be made and the result
stored in memory. For the system described here, the time required for
the A/D conversion is 10 microseconds with an additional 20 microseconds
for execution of the program instructions (see Table I). Hence, data
can be stored in core at a maximum rate of 33,000 words per second. Thus,
for a resolution of 3.3 mV (i.e., one value of cell current every 3.3 mV),

the maximum scan rate is 100 V/sec. Or, for the more typical

63
resolution of 10 mV, the maximum scan rate is 333 V/sec. This scan rate
is about as large as is practicable for cyclic voltammetry, and

therefore this data collection rate was adequate.

3. Data DiSplay. Two forms of data display are incorporated

 

in the software package, and these can be selected yj§_the teletype in
response to questions from the computer. The first display mode
provides rapid inspection of the collected data by plotting them on an
X-Y oscilloscope as cell current (Y-axis) vs, cell potential (X-axis).
This routine uses the two D/A converters (see II. H. 5.) and presents
the raw data - i.e., it is a plot of the unscaled voltages actually
sampled by the A/D converter during data collection. Actual photographs
of the oscillosc0pe screen during this display are shown in Figures 17
and 18.

In the second mode of output, which is relatively time consuming
but provides a permanent record, values of current and the corresponding
potential are typed by the teletype. Of course, prior to listing the
data, the computer performs the arithmetical calculations to convert
voltage to cell current (normalize input of the A/D converter, divide
by load resistor, etc.). Table II is a reproduction of experimental
data actually obtained from a teletype listing.

It is interesting to realize that prior to computerized data
collection, a cyclic polarogram at a scan rate of 20 V/sec (Table II)
could only be recorded by photographing an oscilloscope trace. Comparing
that approach with the extensive data of Table II (wich incidentally,
were obtained in a few minutes) is convincing evidence that computerized

data collection is more than a mere convenience.

64

Figure 17. Illustration of the oscillosc0pic display system
A. Oscilloscope trace of actual cell current vs, potential;
8. Plot of data collected by computer during the recording
of curve A showing one possible display mode. The
system being studied is bromocresol purple in 0.131

citrate, pH 4.8 at a scan rate of 60 V/sec.

65

 

Figure 18.

66

Illustration of the oscilloscOpic display system.

Each point represents the simultaneous display of two
words, the cell current and the cell potential
corresponding to that current. The cyclic voltammogram
is for the electrolysis of bromocresol purple in 0.1 m_

citrate, pH 4.8 at a scan rate of 20 V/sec.

67

 

6&3

Nuuwnhnoa.uoc+
NsownaunnNNIO§
Nata—wwun_uol§
Nouwwwhn_nu..+
NQIuNNhn_nNo.+
mouuunamnnuot+
Naowwnawnnuet+
Nouwnhn_ncu..+
Nooumwhn_nuoc+
Noiunhn_ncuoc+
Nuouuwnohcmon4
Noon—emaonu..+
«comm—oavn~..+
NaowonnOFQNIOO
meowm_oaan..+
mouwnnwmmnuot+
Notunnwmwnu..+
unimpooovpuec+
wanna—n'ohuoc+
«cows—nvnhw..+
«cum—wa_oawou+
Nsuwu_nvw>N.o+
Naowccsmwww.o+
meuwnwwwnonIO+
Neuwnnswmon.o+
Noowcmwn_unoo+
Noouv__cm~noo+
Nonwmmm'nwnofl+
NQIwaF__'m.o+
Nooww_vamnn.o+
Neuwsqwhownoo+
Nutw_upcm>n..+
Notwown_wan..§
Nenwnvwh__v..+
«noun—Nanocot+
Nenuawwnnwcou+
Nonwaonvpmcoo+
wouw_n_wanvoo+
Nsumnvws__ceo+
NSIwwwvwFQCIG+
matwwmruwonIO+
mouwsqmpowneo+
Noam—nonnnn.o+
NauwnwwmnonIQ+
Notwwwwwmwwoc+
Noowo_nvhww.o+
Nonvwsowo_.c+
NquqOFQwh_.o+
Nooumpaanc_.n+
Nouwvmwn_w_..+

 

ucuccau

_o+wn-Nonouo00
_o+w_ooooooouo
_u+w¢msewmhooo
.aemaoa_m¢ho.o
_o+wnnnmwmhc.|
ua+wan_nquh..o
_o+u_Nonnnh..I
_u+w50hcwhs..i
_u+wawvowsp.06
.e+ww~Nwm@h.-o
.oeflwnuhvwh..a
_o+whmwmwnh..o
.o+m-wownh..|
.a+wwo_oacp..0
_s+mwa_oaqh..r
_o+wNwaonvp..o
_o+wn¢s__cp..o
.o+wnnnnnnhocl
_o+wnnnnnnh..0
_o+wueacnuhoco
_u+u~oovnufi.or
_u+wasvmh_houo
.a+wwnwsn_hooo
—o+wmnsmmosooo
_a+wmnem¢ehocu
_o+wwewa_o>..r
_s+wumnawmo.oc
.o+wos__cawouu
_a+w~wa_cmwoou
_a+wnvs~wmooou
_o+m—nnnwmw.uu
_o+wN_ncwpooou
_o+was_nvhv.-o
_s+wmwwnshu..o
_a+whmwwowo.nu
_n+w_mvawu..o
—o+w~nwmwno..o
_n+mo_navnw.00
_s+unsmmonwoao
_u+mamnssvw.oo
.o+wmmnuhco.oo
_s+wsn_Nmnw.oI
_o+m_qa~nnw.-I
_o+ww-n_no.at
_s+wu_n¢-w.-I
_a+wnamnnwoooo
_s+mmsswo_wooo
_o+wcommn_w.ou
.a+m~<wp__w.oo
_e+w_nqm~cw.oo

 

perucouoa

noImuop._vn..¢
neIumncpuun.-+
noImsmnumnnIO+
nonpm.savo.u+
nanwnopn_nv.o+
neIwnopn_nq.-+
nuumwun_~on.-+
nonueanqs~.o+
neIumnmwnnu.o+
mqunnawnn~.¢+
noImnnN~n_n.o+
neIuwmesoo..o+
noImnnwen.n.u+
neowwupuuo..o+
nqumueowa_.o+
nuImumpooa_.o+
noImmnamnn~.¢+
noImswmmwn_.-+
noumww~ow¢_I-+
nonwusuwa..o+
vqumc_nvo~.-+
noImpwwuwo_.c+
oo+woooooo-.o+
nonmnoNon~.o+
nonmsunv-.-+
anuao.nqm~.o+
noImmmhoom_.-+
noImmnmunn~.o+
noImwohoma_.o+
nquemmmwn_.-+
caquq~_~mn.-I
qumcwn.~an.-+
nsImanup...o+
noImmpsovpu..+
cancwn.~an.o+
nuImmpsnv-.o+
conme_nvmp.o+
nquwopoom_.o+
nsIusmwmwn_.o+
neImFNmmwo_Io+
nsImwhsncFNIQ+
nsImqum~__.o+
nonquw~._.a+
qsImewn_~mn.a+
nsImwmhewa_.o+
noIm~n<w~_..o+
nonhmwwwn..o+
nsIuwwpowo..o+
naIwewn_~mn.a+
NeIwnhmowwn.oI

 

ucOLLau

.oImo.~anow.nI
.qu.oooaou.-I
.uImnmesoon.-I
.aomuen.~mn.-I
.aIunnnwmmn.-I
.uImmn.nqnn.oI
.aowuwononn.-I
.sIumoevuenI-I
.u+m.a~n~en.-I
.onnhwmnonIQI
.anmnoecmn.-I
.chqcaeoen.-I
.uImmuomwnn..I
.o+mn.«o~nn.-I
.aqua.oaco.-I
_s+uomaonqn.-I
.oImame__«n.-I
.onennmpnn.-I
.QIucnnnnnn.-I
.o+ma...a~n.-I
.a+m~umcn~n.-I
.stwmmn.~n.oI
.o+w.~qmp.n.oI
_o+wmn-n.n.oI
.uImmnumaun.-I
.QImnmwmnon.oI
.QImmowa.om.-I
.QIwNanmmaq.oI
.n+mhp._qmq.oI
.u+u.oa.aac.oI
.3Iquswmnc.oI
.quonnnwmq..I
.~+mc.ncwpc.-I
.mImmasncsq.-I
_o+unwmmasq.oI
.e+wwwowowc.-I
.uIm.nqA~mc.-I
.nImonNmmnc.-I
.qua.eaqnc.oI
.«Imqsmosnc.aI
.eImqswaooq.aI
.ann~n_ncq.oI
.uImem_~anq.oI
.m+m.<a~nnc.eI
.s+mm~en.nc.oI
.a+wo.n<-~.s-
_o+wva~nn~q.uI
_u+woeumm_c.oI
.s+m~cme..q.oI
.stqumeuc.oI

 

—o vacuuoa

 

eeouou\mu.e> o~ a. sem~ez L..ex o..o e. eomeu

mucosa: Low pafiucouoa mamLo> acoLLau yo uaquao Louaaeou II .unm3m<h

69

 

Natashvopu_o.0
naiunnnnuuaeur
Normanmbn_—..I
Nutmwwun_uqoca
Noowuthh-_..o
«stunnewa._.-I
NOIHQQthfl—ouu
Nouwuhcwh._o-I
Natmnhvwh__.uo
«sowm'nmhn_.or
Nauuwsaqu—oul
Netwohcwh_—oua
Nerwunnnnn_ocr
NoowwanFn-.II
menu—.vawn_..o
Nanwwnnnnn_.00
Natuwm_omc_ooo
Nsnuhwwmwn—IOI
Naomhmwwmn_oor
Nanwncwhow_ouo
ustwmmqnwsuour
Natwmnehcw_..o
Nsnmmnohqo_ono
Nanuwwn_Na—ooo
warm—Nanem_oor
Nnuwwn_nco—oon
NQIwNnnNDD_.-r
Noam—wnmn_u.oo
wean—ncwhuu.00
Nnum_wwmouuono
NaawmsochNNIOI
Nsnwnn_w«nuouo
Nsoumcchwououo
Nana—munchuour
Natuhmonvhuono
Nanmswm_amu.no
Notwnmwmnsnoua
NarmmnswmonICI
menu—nnmnnnIOI
Natwonnwsnn.ou
muuwmhmanvnuno
Nauwwwwwwnn.oc
NaowmnsscwnIno
NsIuN_cmNnn.-t
Nsnunwh__cn.or
Nooummcoh_nooo
NonwcvhuwnN.-0
NquNsn_nQN.-o
NecuwQUh~_Nour
NouumnOFvu_oua

_o+wo_nqpuv.-I
_u+wu~sn.nc.ou
.o+w.qa~nnvool
_o+m~o_Nonv.-I
_o+wnpn_nvcoco
.o+wmmnshvv.un
_a+mm_uaqnv.-I
_a+mwnwmwnv.-o
_o+m_nv>~w<..o
_u+wwwwwwwc.-I
_o+mnwnnosc.un
-o+mq_nvwhc..u
_a+wonnnwwq.oo
.uemuvpmowq.un
_u+w_oo_oaw.oo
.oemps__cmc..r
.oewuowa_on.ui
_o+wn~mnnon.on
_a+mwnowaon.oo
_o+w.svw~.n.oo
_u+w—>vu~_nouu
_a+wunon_~n.nt
_a+mm_—vn~noul
_a+ucnnnnnn.-o
.atmunnupnnoco
_a+wmw~__vn.oo
_u¢mawaonvn.-u
_o+wwm.novnooo
_o+mm~mnmnn.00
_o+wvow>oon.-I
~a+wanopqwnouo
_o+wnpwwuwn.oi
_o+wmasvwhn.-o
_o+w-onamn.oo
~93wmn_nqwa..o
_u+mnnn~onnooo
_o+wapn_umnooo
_s+mnmpomanooo
_s+w_soaoom.-o
_s+w_ncwsaweon
_o+mhcwh__w..o
_s+mcwmun_w..o
.e+wo~aua.m.u.
_a+wno~nn~u.oo
_o+uo~sn_nu.-I
_s+m_va~nnm.uo
.e+w~n—~anw.-I
_o+mnsn_nqw.-I
_o+mnmnupvooot
-a+wnonnonu.ut

quuuoovnN...I
n-quuua.na.-I
nuuunwwwno~out
nocwwcamnnNIII
catwno_nvuh.ur
caumaa.n<u~.o+
cunwcwn_~an.n+
nnIunnusn_n.-+
nanmmopn_nv.o+
noImFNnumoo.o+
nanunmnuwwn.o+
nouwanananIO+
no-uo.nv-u..+
noImonqsuuu.o+
nonunmno_on..¢
nauuanvsuoooo+
noImopmnnquC+
noImnaononn.o+
«onusoum.o_.0+
«coupowa_o_.u+
uaImNnusn_..o+
Nqu~n«5n_..u+
«oIm~n-n_..¢+
unIuNnupn._.o+
Nquvwwn.N_.a+
onuuomcn~_.o+
«oanmmn_~_.-+
~uoumoavn~...+
mouwnnnnnn~Iu+
NaIunnnnnn..o+
mocwnnnnnn_.o+
muummsmunv_..+
NoImanmmo_.-+
weuwwa_oaq_.u+
NcIuaeaon...-+
NoImwa.umc_.o+
wuuwsco-n_.-+
uoImqusoo_.-+
Nouuhmvnwh..o+
«suwwwmnsw_.o+
NauwmaoszNInI
Norww_wansw.u+
Noowwcws__~.o+
Naummvwh__N.-+
Nqunmwnn-Io+
NoIm_wmwn_N.o+
Nauwmnmaam_.o+
«quwqu__u.n+
NoownawnnNNIO+
«qunpswm_u.-+

.o+m~n~mmnw.-I
.a+m_nv-uu.-I
.a+mhwuwuou.ot
_o+u~wwo-u.-I
_s+wao_nqso.-I
.o+m~_nvo~o.-I
_u+wocswoov.-o
_a+m~wm.oao.oo
.s+wms._vaw.uo
.o+w~ononao.-I
_o+wuoua_csocu
.QIwwnuoaopI-I
.o+mun-n~s.-I
_o+mopqop_p.-I
_e+wwwwn.-..o
_o+u~amcn~».-o
_u+mm__va-.uo
_u+munn~pn~.ut
.u+unm~..qp.-I
_e+m~mmonqs.-I
.o+mom_omcp.oo
.o+mn.va~n~.-I
.a+wh~omonp.ou
.sImunehquIQI
_u+mw>~wnup.uo
.u+wamcn~sn.00
_u+mso~vush.oo
_u+m_~mnunp.co
_e+mmn_nqoh.-I
.a+maun_~ap.-I
_a+mqm~eoas..t
.s+m.oaauon.oo
.a+wn.~aneu.-I
.s+w~nvw~aw.co
.o+uscwh_.o.-I
.s+wesamm.o.-I
.s+mcm~nnun.oo
.s+masnc-n.-I
.SstcmNnno..I
.o+wmn_~ann.no
_s+m_hn.nvu..t
.s+wmn_~mnm.uo
.quaqomonm.oI
.s+ww-n.nn..¢
.o+ueonq-n.-I
.o+m<mmnn~m.oo
_s+wssowa_m.-I
_s+wqmwwn_w.oo
.o+weqo~._o.nI
~s+w~ncmpanIQI

7O

4. Background Corrections. Experimental currents measured at a

 

continuously changing potential include a component resulting from the
charging or discharging of the double layer at the electrode-solution
interface (59). These charging current effects are especially pronounced
when the rate of potential scan is increased and/or the concentration of
the depolarizer is decreased. Thus, some method of correcting for charging
current is desirable, and in fact several approaches were attempted. The
simplest approach is illustrated in Figure 19. This approach assumes that
double layer capacitance is independent of potential, so that the current
prior to onset of Faradaic current can be directly extrapolated and then
subtracted from the Faradaic current. Actual blank data as collected and
displayed by the computer are shown in Figure 20, and although not
symmetrical, as would be the case if the blank were absolutely pure,
apparently can be represented reasonable well by straight lines. Since
limited storage is available, it was decided to express the two straight
lines illustrated in Figure 19 in terms of corresponding slope and intercept
values. These slope and intercept values were determined by linear least
squares regression of digital data collected during a blank experiment.

In some cases where accurate background correction is particularly
crucial, the above procedure, while convenient, may not be adequate.
The software provides for this case by providing the option of storing
the entire background current voltage curves on punched or magnetic tape,
and then subsequently calling for these data and performing a point by
point subtraction of the background.

Whereas this approach was almost prohibitively tedious and time
consuming prior to the computerized data acquisition, it is completely
routine with the computer requiring only a few seconds following a typed

request from the teletype.

71

Figure 19. Charging current correction for a reversible cyclic voltammogram
Solid line: experimental data

Dotted line: charging current data

72

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- 120‘

"(E-E°)rmv

73

Figure 20. Blank data collected and displayed by the computer
System being studied is 0.05 M. NaZSO4 in H20 at scan rates of:
A. 65 V/sec
B. 80 v/sec
C. 100 v/sec

Ci

 

74

i
I
I

I
I
l .
II

I
I
|

IWI.LI.LII..._IJ4+.J_I_+44._III-I..I.I.....

I ,I
I M-“~*~P~~.—C’
. 61'.- -boéo~~&o~_.§......‘.. ....'.. coo..- -- -- 1

I

C as. u- uni-.nsn"

a»..- I. nu
”ma-"""

I .

75

5. Data Analysis. In addition to calculating and then typing

 

values of current and potential, the software provides several other
options which the operator can select by making appropriate replies to
questions asked by the teletype.

The first option is whether the current function necessary for
mechanism diagnosis (Ip/VI/z, see Reference 13 and III. A.) should be
calculated. If this option is selected, the data are searched to locate
the peak current, which in turn is divided by the square root of the
scan rate, and the result typed or displayed along with the logarithm
of the scan rate (see Reference 13). The results of this operation can
be rejected, saved, or averaged with the results of an arbitrary number
of similar experiments. Moreover, the results of experiments performed
at different scan rates can be stored and then subsequently all displayed
as a plot of Ip/vl/2 gs, ln (v). This plot presented on an oscilloscope
(an X-Y recorder also can be used) for a reversible system is shown in
Figure 21. Similar plots are discussed in greater detail in Chapter V
in connection with experimental evaluation of the system.

Finally, to illustrate the direct determination of rate constants,
the software includes the option of determining rate constants for a
disproportionation reaction (see Chapter V) from the stored data. The
approach is that of Olmstead and Nicholson (52), and therefore requires
that the computer locate from the experimental data values of: (l) the
cathodic peak current measured to zero current; (2) the analogous anodic
peak current; (3) the switching current; and (4) tau, the elapsed time
from E° to the switching potential (50). These points are illustrated
in Figure 22 which makes it clear that the first three numbers can be
obtained simply by having the computer search the table of current-potential

data. The computer calculates the last parameter, tau, by dividing the

76

Figure 21. Example of computer displayed diagnostic plot of Ip/vv2 gs,
ln v. The system being studied is millimolar CdSO4 in
aqueous 0.05 M. Na2504 from 100 mV/sec to 10 V/sec.

77

 

Figure 22.

78

Cyclic voltammogram illustrating locations of:

IC: the cathodic peak current

IA: the anodic peak current

IS: the switching current

System under study is bromocresol purple in 0.1 M_citrate

buffer of pH 4.8 at a scan rate of 60 V/sec.

79

 

80
potential from E° to the switching potential by the known scan rate. Once
these four parameters are known the equation of Olmstead and Nicholson
can be used to calculate a theoretical value of the peak current ratio
(ia/ic). Next the computer relates ia/ic to the quantity szo* r
(k2 is the second order disproportionation rate constant, Co* the
depolarizer concentration, and T is tau) by numerical interpolation of
the theoretical data of Olmstead and Nicholson. Strictly speaking,
electrode sphericity is required at this point, and as it may or may not
be known, the computer simply determines five values of kZCo* T corresponding
to five typical sphericity factors. Since Co* and T are known, the
computer then calculates k2 from each value of k2Co* T and types the five
values of k2 corresponding to the five sphericity factors. A typical
sample of teletype dialogue and output during this operation is shown

in Table III. The entire operation is illustrated further in Chapter V.

6. The Entire Software Packags, The complete software package,

 

which incorporates all of the features described above is illustrated

by the flow chart of Figure 23. Although basically self explanatory, it
may be helpful to trace the main features of the flow chart. When
started, the program first inquires whether blank correction data for the
chemical system being studied are available. If blank correction data
are available, they are located and blank correction factors calculated.
(The experiment can be performed with or without blank corrections.) The
experimental conditions of scan rate, initial potential, and amplitude

of the triangular wave are set on the instrument, and then in answer to
teletype questions these values are read into core memory through the
teletype. The teletype next requests resolution, and the computer

calculates the delay constant (see IV. C. 2.).

81

Table III. Computer Output Illustrating the Disproportionation Rate
Constants for Five Sphericity Factors. System is Bromocresol

Purple in 0.10 M. Citrate Buffer of pH 4.8 at 50 V/sec.

 

 

LOAD RESISTOR: IOOOD

SCAN RATE MV/SEC: SOOOO

AMPLITUDE MV: 899

PT. SEPARATION NV: 19

START EXPT.

SET UP SR IF BIT O=1 EXIT DISPY

THEN PRESS CONTINUE!

OUTPUT TYPE * DIAG. TYPE- :-

MC: -O.2369132E-O4

BC: +0.29D4919E-D4

MA: +9.2354328E-O4

BA: -D.3¢44l95E-¢4

UNC. IP/V1/2 = +O.432¢398E-¢4

COR. IP/V1/2 = +¢.392¢795E-O4

LN V=+¢.3912022E+¢1

TO ACCEPT TYPE A:A

FOR REPEAT TYPE R

NEW TRIAL TYPE N

RATE K2 TYPE K

DIAG PLOT TYPE D:K

TYPE Y IF E SWITCHING MV=+O.4¢55¢82E+O3 Y
TAU=+O.1855922E-¢2X TAU=+¢.2¢552¢¢E-92
IC=+O.2251523E-O3 IA=+O.8986565E-¢4 IS=+O.14¢6594E-O3
IC=+0.2¢43274E-O3 IA=+¢.6362965E-O4 IS=+0.1421197E-D3
TO ACCEPT CURRENTS TYPE A:A

TO AVERAGE AND FIND K2 TYPE A:A

FOR DISPOR. TYPE KZD AFTER . I

.K20
DISPROPORTIONATION:

IA/IC =+0.7403584E+DO

SPHERICITY K2

g +0.1900840E+¢7

6.25 +0.2193278E+¢7
25.0 +0.2558825E+¢7
56.25 +0.3143696E+¢7
100 0 +0.4167228E+¢7

TYPE 'DSEP' AFTER . TO RETURN TO SEP PROGRAM I

 

82

Figure 23. Flowchart of DSEP, the main cyclic voltammetry program and

K20, the disproportionation rate constant program

83

(_ START )

     
 

BLANK

 

 

Yes J...
ORRECTIO CALCULATE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(:E) CORRECTIO
[:SET EXPERIMENTAL CONDITIONS]
[ENTER EXPT'L. CONDITIONS ]
[ CALCULATE DELAY CONSTANTT:]

START POTENTIAL SWEEP
CHECK EXPT. FLAG
EXPT.
No FLAG
SET
Yes
I GO TO DATA COLLECTION I
_L
[ DISPLAY DATA COLLECTED I
[s DATA ANALYSIS OPTIONS ]
L,

I L
CALCULATE & LOCATE &
LIST ALL I CALCULATE THE
gs, E DATA PEAK CURRENT

FUNCTION

L ,_,

AN '5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

& REPEAT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

"DELETE "0
RESULTS
Yes
L_A STORE RESULTS ”—1
42)
L__CONTINUE OPTIONS**‘]
I
LL_GL__L I . L 'iL
REPEAT TRIAL CALCULATE DISPLAY NEH TRIAL
*‘NITH SAME RATE CONSTANT DIAGNOSTIC HITH NEH
CONDITIONS PLOT CONDITIONS
CALCULATE Eff;
E SNITCHING
‘_qSET E SNITCHING 0
AND REPEAT
Yes
CALCULATE AND OUTPUT
ICO. IAO. ISO. &
TAU EXPT'L, AND TAU
THEORETICAL
AVERAGE ICO. IAO, ISO
TAU EXPT'L G STORE ON
PAGE 0
“ DELETE & No
REPEAT
[EALL IN KZD ROUTINE ]
*_‘STORE RESULTS No

CALCULATE AND OUTPUT
IA/IC AND K2 FOR 5
SPHERICITY FACTORS f

 

 

 

CALL IN DSEP ROUTINE

 

 

 

 

85

When the actual Scan is begun, the computer detects the
instrument flag, and the experimental data are collected. Following
data collection the operator has the option of listing the data and/or
displaying them on the oscilloscope. As an alternative to listing
all data, only the value of the peak current function Ip/v1/2 can be
listed. This peak current function may be accepted, rejected, or
averaged if repeated trials are involved.

Next, various continue options are presented to the operator
through teletype inquiries. For example, if no further data analysis
is desired, the experiment may be repeated with the same experimental
conditions, or a new trial may be begun with different experimental
conditions. If further data analysis is desired, one option is to
display a diagnostic plot on an oscilloscope or x-Y plotter. The
other option is to calculate rate constants for the disproportionation
mechanism. In this case experimental values of ICC, 1A0, ISO, and tau
are calculated and typed so that they may be accepted, rejected, or
averaged for repeated trials. Next, the K20 routine is called into
core memory either from paper or magnetic tape, and the current
ratio ia/iC calculated and listed with rate constants for five
sphericity factors. The main program is then returned automatically
to core from magnetic tape and the experiment begun again with new
experimental conditions.

All of the foregoing options are best illustrated by examining
an actual copy of the teletype listing resulting from a typical
experiment. Such a listing is shown in Table IV; to make this table
understandable, the operator responses to questions “asked" by the
computer have been underlined.

Finally, for the sake of completeness, a listing of the entire

program is included as Appendix B to this thesis.

86
Table IV. Example of Computer Teletype Dialogue

 

 

.WIPl
.CALL BCDb

£59.

.DSEP

TYPE S TO START C TO CONTINUE :s

TYPE Y IF BLANK CORRECTION TAPE IS LOADED g1
BLANK SCAN RATE RANGE 13:
EEAAKWOSWWWBM SR H:+¢.WWW¢E+¢6 SR:+¢.5WWWE+¢4
MMOLAR CON:+D.Ta¢¢¢¢¢E+D3

BLANK CORRECTIONS NILL BE MADE

SEP. DATE:2—l6-7l

EXPT. NO. gfljf"“‘

SOLVENT:25 % MEOH-HZO

ELECTROLYTE:0.l M. CITRATE PH 4.8
REACTANT:BROMOCRESOL*PURPLE

 

 

 

SET BIAS!

THEN PRESS CONTINUE!

SET INITL.POT.!

THEN PRESS CONTINUE!

MMOLAR CON:l;g_

LOAD RESISTOR ngpg

SCAN RATE MV/SEC:§gggg_

AMPLITUDE MV:8_lg_

PT. SEPARATION MV:§_

START EXPT.

SET UP SR IF BIT p=T EXIT DISPY

THEN PRESS CONTINUE!

OUTPUT TYPE * DIAG. TYPE- ;;
MC:-¢.2369T32E-¢4

BC:+¢.29¢4019E-¢4

MA:+D.2354328E-D4

BAz-D.3¢44195E-¢4

UNC. IP/VT/2 =+p.46¢¢¢72E-D4

COR. IP/Vl/2 =+p.43¢63BTE-D4

LN v=+¢.3912p22E+DT

TO ACCEPT TYPE A:A_

FOR REPEAT TYPE R

NEH TRIAL TYPE N

RATE K2 TYPE K

DIAG PLOT TYPE D:K_

TYPE Y IF E SHITCHING Mv=+D.4129343E+D3 .1
TAU=+D.249p842E-D2x TAU=+D.2p552DDE-D2
IC=+¢.3252743E-¢3 IA=+D.1167275E-93 IS=+D.13724D6E-D3
IC=+¢.3¢45¢73E-D3 IA=+D.92D3493E-o4 IS=+D.T3B7DG7E-DB
TO ACCEPT CURRENTS TYPE A:A_

TO AVERAGE AND FIND K2 TYPE A:A_

FOR DISPOR. TYPE K20 AFTER . !

.KZD

V. EVALUATION OF THE SYSTEM

A. Introduction

Naturally, a number of experiments and tests were used to
evaluate the performance of the system. This sequence of tests was,
chronologically, as follows: (l) use of an analog "dummy" cell
consisting of precision resistors (l%, 1000 ohms); (2) use of chemical
systems whose electrochemical behavior is well known; and (3)
measurements on some chemically interesting systems that have not
been studied in detail previously. Each of these is discussed in

the following paragraphs.

B. Performance with a Dummy Cell

Remarkably enough, the hardware (interface) actually operated
the very first time it was connected to the computer and power turned
on. After correcting some fairly minor problems, the basic operation
of the interface was tested by using the A/D converter controlled by
the computer to measure standard voltages from a precision potentiometer
source. Decimal values were then listed on the teletype. Standard
voltages ranging from zero to ten volts were used so that the linearity
and accuracy of the A/D converter and associated amplifiers also
could be evaluated. These were always found to be within the
manufacturer's specifications for the A/D converter (linearity :fl/Z
least significant bit, accuracy :l/Z least significant bit or

:9.0125%, see discussion II. H. 4.).

87

88

Similarly, the D/A converters were checked by loading numbers
ranging from 00008 to 77778 and measuring the output voltages with a
precision potentiometer. Both D/A converters operated within the
manufacturer's specifications (accuracy of :J/Z least significant bit
or 19.01%, see discussion II. H. 5.).

Next, the dynamic range of the system was checked by using one
D/A converter to generate variable frequency triangular waves, and
then using the A/D converter to record the triangular waves. No
distortion between the original and measured triangular waves was
obtained for frequencies of 3 KHz or less.

Finally, the combined system (i,g,, Figure 13) was evaluated
using the precision resistor dummy cell, first with static potential
and current measurements, and then with measurement of current vs:
potential for a triangular wave applied to the dummy cell. In each
of these tests the computerized system functioned within the tolerances
of the various test equipment used (oscilloscope, frequency counter,
digital voltmeter, and potentiometer), and all measurements with the

computerized system were within one percent of the test values.
C. Standard Chemical Systems

'l. Reduction of Cadmium. The electrochemical behavior of

 

cadmium in an aqueous electrolyte is well known; indeed, this system
has perhaps been studied more extensively than any other. Hence,
reduction of cadmium was a logical first choice for evaluation.

A typical cyclic voltammogram for the reduction of cadmium
is shown in Figure 24 (points). Also included in Figure 24 is a
theoretical stationary electrode polarogram (solid line) calculated

from literature data for a reversible two electron transfer reaction

Figure 24.

89

Cyclic voltammogram for reduction of cadmium.
Line: theoretical
Points: experimental
Scan rate: 5 V/sec

Electrolyte: 0.05 M. Na2504

|,p0

200

ISO

IOO

50

-50

-I00

-|50

 

90

 

000

3%.. mixer $33

 

 

E vs. S.C.E., VOLTs

9l

(see Reference 13). The theoretical data were placed arbitrarily on
the potential axis to coincide with the experimental peak potential.
This fit corresponds to an apparent half-wave potential of -0.609 V
gs, S.C.E. which agrees well with the literature value of -0.604 V
gs, S.C.E. (60). Moreover, the A Ep of 33 mV agrees well with the
theoretical peak separation of 29.5 mV or a reversible two electron
reduction. [Note that in this electrolyte cadmium reduction is
reversible at a scan rate of 5 V/sec (27).]

The reduction of cadmium also provided a convenient system for
evaluating the approach incorporated in the software (see Section IV.
C. 4.) for minimizing background. A number of experiments were
performed both with and without background correction. A typical
result, which provides graphical illustration of the correction of
charging current, is contained in Figure 25. These data acquired
by the computer for a rapid scan (where charging current is significant)
are shown before correction (circles) together with data listed by
the computer after it had performed a background correction (triangles).
The improvement in the data is qualitatively obvious. Indeed, the
correction in this case would be essential for any analytical application.

Finally, the reduction of cadmium was used to evaluate the
diagnostic system that was incorporated in the software (calculation
and plot of Ip/VV2 gs, ln (v) - see Section IV. C. 5.). To do this
cyclic voltammograms were obtained for the reduction of cadmium at
twenty to thirty different scan rates. For each of these scan rates
the computer was requested to make the blank correction, locate Ip’
calculate Ip/vV2 and ln (v), type the results, and store the values
in core. In general, for each scan rate three or four experiments were

performed, with the computer requested to find the average of the

several results (see Section IV. C. 5.).

Figure 25.

92

Blank correction of cyclic voltammogram for the reduction
of cadmium.

Circles: uncorrected current

Triangles: blank corrected current

Scan rate: 5 V/seC

Electrolyte: 0.05 M. Na2304

|,pa

200

ISO

IOO—

 

50

 

-50*

-IOOT

'ISO

 

 

93

R

 

__ A3130
0 A
A o
A
o
__ A
o
o
A A
o
A
o
A A A
A o
0 Ag) 0 O
A A
o 0
0A A
88 R 3“ O
A
o
A
A o
o
A
o A A
0A 0
0A
0A A
0A A O
A
0 o
o
l l l
.050 -O.60 -0-70

E vs. S.C.E., VOLTs

Ol>I>O

94

After these data had been collected for the entire range of
scan rates (usually from lOO mV/sec to 100 V/seC), all values of
Ip/VV2 and ln (v) which were previously listed by the teletype are
plotted on the oscilloscope through the D/A display system. A
photograph of one of these oscilloscope plots was shown in Figure 2l.
Although this plot is relatively uninteresting, it suggests a
reversible reduction uncomplicated by coupled chemical reactions

(which is, of course, well known to be the case for cadmium).

2. Reduction of Thallium. As an example of a one electron

 

reversible electron transfer, TlN03 in an aqueous electrolyte was
examined. A typical cyclic voltammogram is shown in Figure 26
(points). Also included in Figure 26 is a theoretical stationary
electrode polarogram (solid line) calculated from literature data for
a reversible one electron transfer reaction. Again, the theoretical
data were placed arbitrarily on the potential axis to coincide with
the experimental peak potential. The experimental fit with theory
corresponds to an apparent half wave potential of -0.475 V gs, S.C.E.
which agrees well with the literature value of -0.48 gs, S.C.E.

(6l). The experimental A E of 62 mV also agrees well with the

P
theoretical value of 59 mV for a reversible one electron reduction.

To illustrate that the diagnostic plots displayed by the
computer are also indicative of the number of electrons involved in the
reduction, Figure 27 includes computer acquired diagnostic plots for
both the reduction of cadmium (II) (curve A) and the reduction of

Thallium (I) (curve B). The fact that thallium(I) also is reversible

and uncomplicated, but involves only one electron, is clearly evident.

95

Figure 26. Cyclic voltammogram for the reduction of thallium.
Line: theoretical
Points: experimental
Scan rate: 5 V/sec

Electrolyte: l M. NaOH

 

 

96

«.30., ..m.o.m .m> m

 

OED I 00 .0. 00.0.. 0' .0I Onén
_ _ A _
oo oo
o o ..
O 100‘
O
O
O O
00 I
O .J
O
0 ll 0
O 0 O
O
OO
O O 00
OO
000 O 0
000 O IJOO.

loo.

 

01!‘|

97

Figure 27. Plot of computer diagnostic data for cyclic voltammetry
experiments.
A: CdSO4 in 0.05 M. Na2504
B: TlN03 in l M. NaOH

98

0.0. 0.. 9.0

 

m 0000000 0 0000000 0 0

4 00000000 0 00000000 0 0

 

_.0

N6

m6

(‘Z/l) A/d'

v.0

m6

99
The tremendously improved quality and accuracy of the computer
acquired data have been alluded to elsewhere in this thesis. Here,
it is pertinent to point out that a plot of the type of Figure 2l
would require about l00 man-hours to reach fruition under conventional
methods of data acquisition and analysis, whereas with the
computerized system a plot such as Figure 2l can be obtained in about

four man-hours.

3. Reduction of Sulfonephthalein Indicators. This laboratory

 

has recently been interested in the reduction of sulfonephthalein
indicators. In particular, the reduction of phenol red was studied
very extensively by Kudirka, and the reduction mechanism shown

unequivocally to be (62):

0‘ OH OH

+
H (I
H c+ ZHO-Q—c-t +Ie :HOQ—C. 0’
@305 @305 @803
(lo) (I) (II)

()H
(3H

.. _. _ (lb)
HoG’gj/sg+|e _ HOG—$03

(II) (III)

100

F’ ()H "I (3" OIH

 

 

(ll) ‘" (III)

0.1 0!!

(Id)
H0< >._c + "T -o HO-< >'—C-H
@30- 63°53
3
(III) (IV)

Kudirka also measured rate constants for Reaction lc using both
electrochemical and nonelectrochemical methods. Kudirka obtained
other extensive electrochemical data for phenol red to elucidate the
mechanism according to the theory of Olmstead and Nicholson (52).

Kudirka studied several other sulfonephthalein indicators in
addition to phenol red, but much less extensively. In particular, no
diagnostic plots were reported (although diagnostic data over small
ranges of scan rates were reported), and in several cases he assumed
a disprOportionation mechanism on the basis of classical polarographic
data (62).

The computerized system was therefore used to confirm the

mechanism for reduction of the four indicators listed in Table V.

lOI

 

 

 

 

 

z a?»
:nom o co
- can
n z u 0 so ”3303;
.v ..0. :AV
:.v v.. :nv
n O
..m ..u
apnea; Pommgoosocm umm —o-mmogxmoeogm uncaoasoo
:nom
_ :nom
o
‘/ :fl.\ u
. ”mgzpuacum
:o 0 go
.0
com Foamsnogopgu umm Focmcm nucsousou

 

 

mcoumuwncH :_mpm;p;amcomF:m .> mpnmh

102

Of these, phenol red is the only one studied extensively by Kudirka;
bromopyrogallol red has not been studied previously.

The experimental approach was exactly the same as described
above for cadmium and thallium, except that the total range of scan
rates was different for each compound. The diagnostic data generated
by the computer for each compound are shown plotted on the same graph
in Figure 28. The morphology of these plots is precisely that expected
for a disproportionation (52), and therefore it can be concluded that
the general mechanism for reduction of each of these compounds is
the same as for phenol red. Moreover, the fact that each of the
curves is displaced along the abscissa reflects the fact that the rate
of disproportionation is different for each compound. Indeed, the
position of the curves for phenol red, chlorOphenol red, and bromocresol
purple is consistent with the rate constants reported by Kudirka.

In addition to obtaining diagnostic plots for each compound,
the software described earlier (Section IV. C. 5.) was used to calculate
rate constants for the disprOportionation reaction. These rate
constants obtained from the computer are listed in Table VI together
with values reported by Kudirka. The agreement is satisfactory and
within the larger experimental error associated with Kudirka's
measurements for fast scan experiments. The rate constant for
bromopyrogallol red has not been reported earlier, but the value in
Table VIis consistent with the structural differences between this

molecule and phenol red.

Figure 28.

103

Computer diagnostic plots for cyclic voltammetry experiments
of sulfonephthalein indicators.

l: Phenol red

Chlorophenol red

Bromopyrogallol red

wa

Bromocresol purple

 

104

0.00.

0..

..0

 

0..

(Z/IIA/d'

, 0.N

105

Table VI. Rate Constants of Sulfonephthalein Indicators

 

 

Compound Rate Constant,a Literature,b

M'I-sec'] M'I-sec'1

0 p = 6.25

 

Phenol Redc 0.341 E + 03 0.384 E + 03 0.337 E + 03

Chlorophenol Red 0.220 E + 04 0.250 E + 04 0.113 E + 04

Bromopyrogallol Redd 0.145 E + 05 0.154 E + 05 --
E

Bromocresol Purpled 0.190 + 07 0.212 E + 07 0.20 E + 06

 

The sphericity factor was not determined for the electrode used in
these experiments. Thus, rate constants are listed for a planar
electrode (p = 0) and for a large spherical correction (p = 6.25)
to indicate the magnitude of error involved with ignoring effects
by sphericity in this case.

b Reference (62). Bromopyrogallol red has not been studied previously.

Aqueous solution, 0.20 M. acetic acid, 0.20 M. sodium acetate.
pH = 4.8.

d 25% (by weight) methanol-water, 0.10 M. citrate buffer, pH = 4.8.

VI. COMPUTER CONTROLLED CLASSICAL POLAROGRAPHY

A. Introduction

 

The major objective of the thesis research was to develop and
evaluate the computerization of cyclic voltammetry. Nevertheless,
since classical (dropping mercury electrode) polarography is a useful
adjunct to cyclic voltammetry, some preliminary work on computerization
of classical polarography also was carried out. This work suggests
some major advantages for computerized polarography; moreover, the
approach developed illustrates the interactive use of a computer
wherein the computer not only collects data, but actually controls
the experiment. Hence, although preliminary in nature, this work is

of sufficient interest that the results are included in this thesis.

B. Classical Polarography and Possible Approaches

As is well known, polarography involves measuring the current
voltage curve for a dropping mercury electrode (dme). In principle,
the technique requires potentiostatic measurements of current, but
usually in practice the potential is scanned so slowly (l-5 mV/sec)
that potential during the life of a single drOp is effectively constant.
Hence, the experiment is controlled by the computer through use of a
D/A converter to provide the applied potential. Obviously, a number
of approaches are possible; the one described here was adapted in
part because it requires no modification of the hardwire interface
described earlier. (This fact further illustrates the versatility
achieved by using software to control operation of the interface.)

106

107

l

l. Control and Acquisition of Data. The simplest approach is
to use one of the two D/A converters in the interface to apply the
desired potentials to the dme through a potentiostat. In this way, the
computer steps the potentials through the polarogram so that each
current measurement is made at truly constant potential. Hence, at
the start of the experiment the D/A converter's output is connected
to the control point of a potentiostat (see Figure 29) and the D/A
converter set to the initial potential for the experiment. Then,
following each successful current measurement, the potential is advanced
to a more negative value. For convenience, the initial potential and
step size (or increment) are entered gjs_the teletype in reSponse to
an inquiry from the computer. The computer then does the necessary
arithmetic to convert the decimal values entered in millivolts to
the proper binary words to be loaded into the D/A converter. [For
example, the D/A converter output is 0 to ID V full scale, so that an
initial potential of -0.5 V gs, SCE corresponds to one-twentieth of
77778, or 03l58. Also, the smallest incremental step corresponds
to complementing the least significant bit in a twelve bit word, or
2.5 mV. This resolution is more than adequate for any polarographic
experiment.]

Thus, with a computer, operation and application of the
potential is simple, and the major problem is measuring the current
and synchronizing advancement of the potential. Of course, current
could be measured continuously during the life of a drop, with the
potential being advanced immediately following detachment of a drop.
Alternatively, current could be measured at a fixed time during the
drop-life. This latter approach is common, and usually accomplished

with the aid of a mechanical drop-knocker, which ensures constant drop

Figure 29.

108

Potentiostat for computer controlled classical polarography

”7330
DUO

CE
RE
NE
LR

10 KA, 1%

10 KA, 1%

50 KA, 1%

50 KA, 1%

50 KA, 1%

50 A ten turn potentiometer

1 KA ten turn trim pot

control amplifier, Analog Devices 143 A
current follower, Analog Devices 143 A
inverter, Analog Devices 142 B

current amplifier, California Electronics
differential ampl. 175

counter electrode
reference electrode
working electrode

load resistor

 

('1
l

 

 

.,
9

So .

109

 

 

 

 

 

 

 

 

 

 

 

 

 

110
time for a dme. Unfortunately, a computer controlled drop-knocker
would have required modification of the interface, and therefore an
alternative approach was sought. This approach involves continual
(actually, once every millisecond) measurement of current and comparison
of successive values, drOp detachment being indicated by a current reading
that is considerably less than the preceeding value (this locates
drop detachment with an uncertainty of about two milliseconds, which
is negligible since drop life is typically 5 seconds). Once the
computer determines that the drop has detached, the computer's clock
is used to time precisely a delay of 4.5 seconds, after which time
the cell current is measured. By using a dme with a natural drop-time
greater than 4.5 seconds, this approach produces a polarogram
correSponding to a dme with a constant drop-time of exactly 4.50
seconds.

When this approach was first attempted, it was found that the
results were unreliable because of random spurious noise. Moreover,
the interference of noise was effectively enhanced by the rapid
digitization rate (33 KHz) available with the A/D converter. In
other words since only 33 microseconds are required to digitize an
analog voltage, a spurious noise Spike of very short duration
(2 msec) could actually be accepted as the correct current (this
effect is illustrated in Figure 30 which shows spurious noise causing
a large error in measured cell current). This problem was circumvented
by what amounts to time or ensemble averaging. This time-averaging
is possible for a single polarographic experiment because the maximum
rate of data acquisition is so large that many measurements of the
current can be integrated over a time increment for which the true

cell current is essentially constant. For example, 51210 measurements

Figure 30.

111

Effect of spurious noise on dme current.

A. Current gs, normal time scale

B. Current gs, expanded time scale

An A/D conversion could occur during the noise spike

resulting in a serious error in recorded signal.

1,;30

1,;00

4.0

2.0

4.0 ‘—

2.0—

 

 

112

NOISE

 

KSIONAL A

 

 

”'9- 5.0
0.002
Tl «E, SE 0.

-|l- aapsec.
NOISE

SIGNAL B

 

‘4 0.002 secr-
TIN£

113

of current can be obtained in 15.5 milliseconds. This means that if
current measurement is begun at 4.50 seconds into the drop-life, it
is completed at 4.5155 seconds; over this time window the true cell
current is constant within 0.054% (i.e., between i] = k(4.500)1/6 and
i2 = k(4.515)1/6 the current has changed only 0.054%). Obviously,
by averaging 512 values of current the influence of random noise is
diminished dramatically. [The choice of 51210 measurements was not
completely abritrary, since division by 51210 (= 29) with the PDP-8/I
does not require a library software routine.] Thus, the control and
acquisition involve the following operations:

(1) measure current and compare successive values until drop
detachment is detected;

(2) delay 4.50 seconds;

(3) make 512 measurements of cell current;

_ (4) average the 512 readings, and store the result;

(5) advance the applied potential by the specified increment; and

(6) return to step (1) above.

This approach provided for excellent control and acquisition of
very accurate data. The software further provides for display of the

data and some data analysis; these functions are described next.

2. Data Display. For reasons analogous to those described in
connection with the cyclic voltammetry experiment, diSplay of experimental
data is important because it gives an immediate estimation of the
success or failure of the experiment. As with cyclic voltammetry,
two diSplay modes are provided. The visual display is obtained with
an X-Y plotter, which plots the data as they are collected. The
X-axis of the plotter is connected directly to the digital-analog

converter used to apply the potential to the electrochemical cell.

 

114

The other D/A converter is connected to the Y-axis and it is used to
display the average value to the 512 current measurements. Thus,

the “digital polarogram" is visible to the operator during the course
of the entire experiment. A sample of such a polarogram is shown in
Figure 31 where it is compared with the "actual" polarogram recorded
in the conventional fashion. Of course, the operator also has the
option of having the exact values of potential and current listed

by the teletype.

3. Data Analysis. Data processing features were incorporated
in the software package primarily to evaluate the efficacy of this
approach. Hence, the only data treatment in the current version of

the software is analysis according to the classical equation
E = E1/2 + RT/nF 1n (Id-I)/I (l)

where Id is the limiting current (cf., Figure 31), I is the current
at potential E, fl_IS the number of electrons, E1/2 is the halfwave
potential (cf., Figure 31), and the other constants have their usual
meaning.

In cases where Equation 1 is applicable, the implied plot
of potential gs, log (Id-I)/I is the accepted way to determine El/Z
(from the intercept) and g_(from the slope). The software accomplishes
this analysis by a linear least squares regression of the data
according to Equation 1, where values of the potential are assumed to
be accurately known. To do this, the operator supplies the computer
with three key potentials, namely the potential of the limiting current
region, (E1), and the potentials bounding the rising portion of the

polarogram, (E2 and E3) (see Figure 31). The computer then searches

Figure 31.

115

Sample data display of computer controlled dme polarography.

Id: limiting current

E1/2: halfwave potential

E]: potential of limiting current

E2: potential bounding top of rising portion of the
polarogram

E3: potential bounding bottom of rising portion of
polarogram

Polarogram is for millimolar CdSO4 in 0.10 M. Na2504.

Solid line: computer controlled polarogram

Dashed line: conventional polarogram

 

 

 

|,po

MOI—r

30° —

2.0)—

I.O

 

116

l 1

-0.40 -0.

E2 - ’3‘

l J 1

50 -0060 - 0070 -0080
E vs. S.C.E. , VOLT s

117
the table of experimental current-potential data, locates and calculates
the limiting current, and then calculates values of ln (Id-I)/I for
all values of current between potentials E2 and E3. From the least
squares analysis values of s_and El/Z are calculated and listed on

the teletype.

C. The Software Package for Classical Polarography

Each of the features described above was combined into a single
package which operates on the basis of extensive dialogue between
operator and computer gis_the teletype. The entire operation is
best described with the flow chart in Figure 32. Initially, the
computer requests through the teletype the experimental values of
load resistor, initial potential, final potential, and point
separation (potential increment) that the Operator wishes to use.
This initial potential is then applied simultaneously to the cell and
the X-axis of the X-Y plotter. After receiving a signal from the
operator, the program tests for drop detachment, then goes into its
data collection routine. The average current is stored in memory
and displayed on the Y-axis of the X-Y plotter. The potential is
incremented and the data collection process repeated until the final
potential is reached. The program then requests values for E], E2, and
E3 and calculates and then plots ln (Id~I)/I gs, E on the X-Y
plotter superimposed on the polarogram. Finally, the least squares
values for s_and EJ/z are printed on the teletype. Table VII is an

example of the teletype listing during execution of a typical experiment.

0. Discussion and Evaluation
The polarography system as developed to date has proved to

be very convenient. Operation is extremely simple, yet the system

118

Figure 32. Flow chart for computer controlled dme polarography

119

 

(;_ START T)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INITIAL DIALOGUE
J. I i J. I
LOAD INITIAL LIMITING POINT
RESISTOR POTENTIAL POTENTIAL SEPARATION
E. s; L, L
1
CALCULATE
POTENTIAL
LOAD DACS
APPLY E T0

CELL & X-AXIS k
OF RECORDER

 

 

 

 

 

.___{_TEST FOR DROP |

 

DROP
L"‘No OFF
?

Yes

 

DELAY 4.5 SEC

1

COLLECT &
AVERAGE

512 CURRENT
VALUES

_.1

STORE AVERAGE
CURRENT &
POTENTIAL IN

CORE
1 I

a 8

 

 

 

 

 

 

 

 

 

 

 

 

120

C1

1

DISPLAY AVERAGE 1
.L___CUBBENI_QN_1;AXI§

 

 

 

[sINCREMENT POTENTIALI

MORE

 

 

POINTS
?

No

 

REQUEST REDUCTION

 

 

POTENTIAL RANGE

 

1

Yés

 

SEARCH DATA,
CALCULATE

PLOT LN (ID-I)/I
gs, E

 

 

 

 

AL

 

LEAST SQUARES
ANALYSIS OUTPUT
'N' & 'E1/2'

 

 

 

LIST

 

 

DATA

Yes

 

LIST ALL
I vs. E
DATA'

L

STOP

 

 

 

No STOP

’0

 

121

Table VII. Sample Teletype Listing During a Computer Controlled DME

Polarography Experiment

 

 

DME POLAROGRAPHY DATEz6-9-7O
SOLVENT: H20

ELECTROLYTE: 0.10 M. NAZSO4
REACTANT: 0.001 M. CDSO4

LOAD RESISTOR:10000
INITIAL POTENTIAL MV:30¢
LIMITING POTENTIAL MV:900
PT. SEPARATION MV:5

PRESS CONT TO START EXPT.
E1 MV70¢
E2 MV650
E3 MV550

SLOPE: +0.7695312E+02

N =+0.1969999E+01
INTERCEPT =+0.4694141E+02
E1/2=-0.6099999E+00

 

 

122
provides considerable versatility and flexibility. In fact, since all
parameters are set through the teletype in terms of English statements,
the computerized system actually requires less expertise on the part
of the operator than a conventional polarograph.

To date the system has not been tested extensively, but the
polarogram for the reduction of cadmium in Figure 31 agrees well with
the polarogram obtained with a commercial instrument. The data
analysis routine for this polarogram (Figure 31) gives a value of
1.97 for g, and an E1/2 of -O.610 V gs, SCE (the value from analog
recording is -O.6ll V. gs, SCE). Presumably, of course, the computerized
data are the most precise because of the precision of the A/D
converter (0.1%) and because of the time averaging.

Certainly the system described here could be improved
considerably in terms of software without further changes in the
interface. But even without further improvements, this system

possesses very significant advantages over conventional polarographs.

VII. CONCLUSION

A general approach to the interfacing of a digital computer to
laboratory experiments has been presented in this thesis. To aid
in understanding the design of the interface, the basic logic gates.
the interface components, and the features of data transfer within
the interface have been discussed. A very versatile interface which
can be used directly to computerize Virtually any measurement performed
in a chemical laboratory has been described in detail. The computerized
data acquisition system has been applied to cyclic voltammetry
studies for the elucidation of electrolysis mechanisms and has resulted
in vastly improved data collection and analysis capabilities. Finally,
the interactive use of a computer in the laboratory has been demonstrated

by the computerization of classical polarography.

123

REFERENCES

Chm-kw

\I

10.
11.
12.
13.
14.

15.
16.
17.
18.
19.

REFERENCES

Booman, G. L. Anal. Chem., gs, 1141 (1966).

Brown, E. R., Smith, D. E., and Deford, D. 0., Anal. Chem., gg,
1130 (1966).

Lauer, G., and Osteryoung, R. H., Anal. Chem., gg, 1137 (1966).
Lauer, G., Abel, R. and Anson, F. C., Anal. Chem., gs, 765 (1967).
Jones, D. 0., and Perone, S. P., Anal. Chem., 3g, 1151 (1970).

Hicks, G. P., Eggert, A. A., and Toren, E. C., Anal. Chem., fig,
729 (1970).

Ramaley, L., and Wilson, G. 5., Anal. Chem., 5;, 606 (1970).
Sybrandt, L. B., and Perone, S. P. Anal. Chem., gs, 382 (1971).

Perone, S. P., Jones, D. 0., and Gutknecht, N. F., Anal. Chem.,
51, 1154 (1969).

Digital Equipment Corporation, "Small Computer Handbook", 1970.
Ramaley, L., Chemical Instrumentation, g, 415 (1970).

Keller, H. E., and Osteryoung, R. A., Anal. Chem., gs, 342 (1971).
Nicholson, R. S. and Shain, 1., Anal. Chem., ss, 706 (1964).

Matheson, L. A., and Nichols, N., Trans. Electrochem. Soc., gs,
193 (1938). ‘

Randles, J. E. 3., Trans. Faraday Soc., 55, 327 (1948).
Seveik, A., Collect. Czech. Chem. Commun., 1s, 349 (1948).
Delahay, P. J., J. Amer. Chem. Soc., gs, 1190 (1953).
Nicholson, M. M., J. Amer. Chem. Soc., gs, 2539 (1954).

Frankenthal, R. P., and Shain, I., J. Amer. Chem. Soc., lg,
2969 (1956).

124

20.
21.
22.

23.
24.
25.
26.
27.
28.

29.

30.
31.
32.
33.
34.
35.
36.
37.
38.

39.

40.

41.
42.
43.

125
Reinmuth, N. H., J. Amer. Chem. Soc., 22, 6358 (1957).
DeMars, R. D., and Shain, 1., J. Amer. Chem. Soc., s1, 2654 (1959).

Gokhshtein, A. Y., and Gokhshtein, Y. P., Dokl. Akad. Nauk
SSSR, lgl, 601 (1960).

Reinmuth, w. H., Anal. Chem., gg, 1793 (1961).
Reinmuth, N. H., Anal. Chem., gg, 185 (1961).
Olmstead, M. L., and Nicholson, R. S., Anal. Chem., gg, 150 (1966).
Matsuda, H., and Ayabe, Y., Z. Electrochem., ss, 494 (1955).
Nicholson, R. S., Anal. Chem., s2, 1351 (1965).

Gokhshtein, Y. P., and Gokhshtein, A. Y., Dokl. Akad. Nauk
SSSR, 12s, 985 (1959).

Gokhshtein, Y. P., and Gokhshtein, A. Y., in "Advances in
Polarography", Longmuir, I. S., ed., Vol. II., Pergamon Press,
New York, N.Y., 1960, p. 465. .

Polcyn, D. S., and Shain, 1., Anal. Chem., gg, 370 (1966).

Polcyn, D. S., and Shain, 1., Anal. Chem., gg, 376 (1966).
Berzins, T., and Delahay, P., J. Amer. Chem. Soc., gs, 555 (1953).
Nicholson, M. M., J. Amer. Chem. Soc., gs, 7 (1957).

Nopschall, R. H., and Shain, 1., Anal. Chem., ss, 1514 (1967).
Hopschall, R. H., and Shain, 1., Anal. Chem., s2, 1527 (1967).
Hopschall, R. H., and Shain, 1., Anal. Chem., ss, 1535 (1967).
Hulbert, M. H., and Shain, 1., Anal. Chem., fig, 162 (1970).
Saveant, J. M., and Vianello, E., in "Advances in Polarography",
Longmuir, I. S., ed., Vol. 1., Pergamon Press, New York, N.Y.,
1960, p. 367.

Saveant, J. M., and Vianello, E., Electrochim. Acta, 19, 905
1965).

Saveayt, J. M., and Vianello, E., Electrochim. Acta, s, 905
1963 .

Saveant, J. M., and Vianello, E., Compt. Rend., gss, 2597 (1963).
Nicholson, R. S., and Shain, 1., Anal. Chem., s1, 178 (1965).
Nicholson, R. S., and Shain, 1., Anal. Chem., s1, 190 (1965).

45.
46.
47.

48.
49.

51.

52.
53.

54.
55.
56.
57.

58.

59.

60.

61.

62.

126
Olmstead, M. L., and Nicholson, R. S., J. Electroanal. Chem.,
lg, 133 (1967).
Schuman, M. S., Anal. Chem., 31, 142 (1969).
Schuman, M. 5., Anal. Chem., 52, 521 (1970).

Saveant, J. M., and Vianello, E., Electrochim. Acta, lg,
1545 (1967).

Nicholson, R. 5., Anal. Chem., s1, 667 (1965).

Kudirka, P. J., M. S. Thesis, Michigan State University, East
Lansing, Michigan, 1968.

Olmstead, M. L., Ph.D. Thesis, Michigan State University, East
Lansing, Michigan, 1968.

Olmstead, M. L., Hamilton, R. 6., and Nicholson, R. S., Anal.
Chem., 51, 260 (1969).

Olmstead, M. L., and Nicholson, R. S., Anal. Chem., 31, 862 (1969).

Vleek, A., in “Progress in Inorganic Chemistry", Zuman, P., ed.,
Vol. 5, Interscience, New York, N.Y., 1963, p. 211.

Booman, G. L., Anal. Chem., gs, 213 (1957).
Schwarz, N. M., and Shain, 1., Anal. Chem., ss, 1770 (1963).
Underkofler, N. L., and Shain, 1., Anal. Chem., ss, 1779 (1963).

Malmstadt, H. V., Enke. C. G., and Toren, E. C., "Electronics for
Scientists", N. A. Benjamin, Inc., New York, N.Y., 1963.

Ross, J. N., DeMars, R. 0., and Shain, 1., Anal. Chem., gs,
1768 (1956).

Delahay, P., "New Instrumental Methods in Electrochemistry",
Interscience Publishers, New York, N.Y., 1954, p. 130.

Frishmann, J., Ph.D. Thesis, Michigan State University, East
Lansing, Michigan, 1966.

"Handbook of Analytical Chemistry", Meiter, L., ed., McGraw-Hill
800k CO” New York. N.Y., 1963’ p. 5'80.

Kudirka, P. J., Ph.D. Thesis, Michigan State University, East
Lansing, Michigan, 1971.

APPENDICES

APPENDIX A

5991c Print of the Interface

The following diagram is a logic print of the interface presented
in block form in Figure 13. Individual circuit cards are enclosed
in dotted lines. The notations M 103, A 123, etc. refer to Digital
Equipment Corporation Integrated Circuit FLIP CHIP Modules. The
notations K 13, L 22, etc. refer to locations on the interface
connector block while the notations A l, D 2, etc. refer to pin

connections of the plug in modules.

127

128

 

               

 

 

 

 

 

 

 

 

 

m_ 2.. u: “a: u: :3. .
. 132: u 35. «.3 _ pawn... in: 5. a x u a. U
__::.._;.._:__;_:: .. u
.5 .5 .00. Ana-:3 _
.hl r1. _
_. a! c» u: 42.: _ nu. ..> a: 4:: u
_ L., .._. .._.. n E... .a .... - - ------ :-------_
11 | I I I II I I I I I mIIIIIII.II1HIIII IIIIIIIIIIHIIIIII IIIIO.0_

 

“to.

 

.LO. Ana-Io

                       
  

.

W ,

 

 

   

 

 

 

 

« 111111u-111111»1o.1..-1--.-
: .3“
L
_ .
,_ _
.h. .
_ .
_ .. " IN‘O.
. 3.. 22. .
_
. an. a:
_ /
.
_ 3.3:! n...
. - - -----.£....-----L
1.. .
_. _
_ v.3.
. .
_
_
. sec. _
.
3o... _
2.... .._
.
.

 

 

 

APPENDIX 8

Software for chlic Voltammetry

 

The following software was developed for the cyclic voltammetry
experiment. The program instructions are presented in both octal
and mnemonic form along with the corresponding octal core location of
the instruction. The program is presented as a reproduction of
the exact print-out listed on the teletype by the computer. The

program is presented in the following form:

Octal address Octal instruction Mnemonic
in core code instruct1on

 

 

129

0000
0001
0002
0003
0004
0005
0006
0007
0010
0011
0012
0013
0014
0015
0016
0017
0020
0021
0022
0023
0024
0025
0026
0027
0030

0063
0064
0065
0066
0067
0070
0071
0072
0073
0074
0075
0076
0077
0100
0101
0102
0103
0104
0105

0000
0000
0000
0000
0000
7400
7200
5600
0000
0000
0090
0000
0000
0000
0000
0000
4000
4042
4200
4205
4217
4227
4234
4235
3352

0000
0001
6000
0000
0000
0000
0000
0000
0000
0000
0004
2400
0000
3152
3340
0000
0000
0000
0000

130

IPAGE ZERO CONSTANTS USED
IIN VARIOUS SUBROUTINES

*0

PRES:

*63
DEED:
MINI:

CHIAS:

CINPT:

EXP:

BAIS:

BINP:

ZERO:

SKL:

0 IINTERRUPT

0

0

0

0

7400 IFPNT INPUT

7200 IFPNT OUTPUT

5600 IFPNT INTERPRETER

0 /USED BY MESAGE SUBROUTINE
0 /LOCo 10-17; AUTOINDEX
0

0

0

00

0

0

4000 IFCVI POINTER

4042 /MESAGE POINTER

4200 IIYPE I CHARACTER PT.
4205 ITY2 POINTER

4217 ITYCR POINTER

4227 ITYSP POINTER

4234 ITYTB POINTER

4235 ITYDIG POINTER

3352 IPRES CONT. PT.

ILOC. 40-62 USED BY FPNT.

0

0001

6000

0000

0

0

0

0

0

0

0004

2400

0000

3152 /USED TO STORE BIAS READING
3340 ISTORE BIAS + INITL- POT-
0

0

0

0

0106
0107
0110
0111

0112
0113
0114
0115
0116
0117
0120
0121

0122
0123
0124
0125
0126
0127
0130
0131

0132
0133
0134
0135
0136
0137
0140
0141

0142
0143
0144
0145
0146
0147
0150
0151

0152
0153
0154
0155
0156
0157
0160
0161

0162
0163
0164
0165
0166
0167

0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0200
0202
0000
0000
0000
0000
0003
2232
7343
0004
2701
5242
0014
3777
4000

SRH:

DSR:

SR:

LR:

P:

MC:

BC:

MA:

BA:

T1:

T2:

RUFF:
BUFFI:
BUFFPT:
CONC:

N46:

N11:

N7:

SSSSNNGSSGSQSS‘S‘GGGGSSGSGGSGSGG‘SSSGSSIS-$888

S
S
G
U

2232
7343
0004
2701
5242
0014
3777
4000

131

/4096

0170
0171
0172
0173
0174
0175
0176
0177

0200
0201

0000
0000
0000
0000
0000
0000
1301
0000

4722
4407

132

T3:

T4:

888588

ENTOR: 1301 IPOINTER BIN.
PONTS: 0 1N0. OF DATA PTS:

T0 FPNT: ENTER
COLLECTED

XLIST
FIXTAB
PAUSE
XLIST
I/DSEP PT1 3'8‘71

IBY ENTERING SCAN RATE: AMPLITUDE:

IAND POINT SEPARATION: THE DELAY FOR
IDATA COLLECTION WILL BE CALCULATED:
IPROGRAM HILL COLLECT DATA VIA ANALOG
/-DIGITAL CONVERTER: STORE DATA IN
ICORE: THEN EITHER OUTPUT DATA OR
ICALULATE IP/VCl/Z) VS LN V0 IF BLANK
ICORRECTION DATA AVAILABLE RESULTS
INILL BE CORRECTED FOR BLANK: IP/(VI/E)
IRESULTS ARE ACCEPTED OR

IREJECTED AND MAY BE AVERAGED BEFORE
ISTORING FOR COMPUTER DIAGNOSTIC PLOT:
IDISPROPORTIONATION K2 RATES ARE..
ICALCULATABLE

IDIRECTORY

l5'30: PAGE 0 POINTERS FOR SUBROUTINES
l40’62: SPACE USED BY FPNT PACKAGE
/102-1778 PAGE ZERO CONSTANTS

/2008 MAIN PROCESSOR

/4008 BIAS: PRINT: SR: AMP:
I600: INITL: WRITE: START:
/10003 DISPY

[12008 DATA OUT

/14008 FIND OUT} IS BLANK AVAILABLE

/16008 LOCATE: PLACE: AND DECIDE

l20008 DIAG. CRITERIA PART I3 FIND IP

l22008 WHAT DO YOU WANT

/24008 DIAG: CRITERIA PART II: ENTo: PLOT
l26008 MSECT: DELAY CALCULATION : IP AVERAGE
[27303 STARTING ROUTINE

/30008 ELAMBDA AND TAU CALC.

l32008 INSERT PGO: E SWITCHING CALC:

I34008 DISPILOCATE ICO: IAO: ISO

/36008 BLANK CORRECT ICO: 1A0: ISO

/40003 UTILITY ROUTINES AND FPNT PACKAGE
*200'
BEGIN:

PS: LOAD:
UDLY: MDLY

DACL

JMS I INITL / PRINT INITIAL DIALOGUE
FPNT

0202
0203
0204
0205
0206
0207
0210
0211

0212
0213
0214
0215
0216
0217
0220
0221

0222
0223
0224
0225
0226
0227
0230
0231

0232
0233
0234
0235
0236
0237
0240
0241

0242
0243
0244
0245
0246
0247
0250
0251

0252
0253
0254
0255
0256
0257
0260
0261

0262

5102
6170
0000
4736
4772
4405
4407
6154
0000
4766
4405
4407
6121
0000
4734
4405
4407
6116
0000
4735
4405
4407
6344
0000
4743
4405
4407
6347
5344
4357
6124
5347
4116
3355
6352
1064
0000
1045
7500
5253
5257
4724
1332
3331
5274
4407
5352
3355
2360

BIGOT:

RESET:

MSEC:

USEC:

133

FGET ZERO

FPUT T3

FEXT

JMS I BIAS / READ BIAS AND INITL- POT.
JMS I CONCT

FIN

FPNT

FPUT CONC

FEXT

JMS I LOADT / REQUEST "LOAD RESISTOR"
FIN

FPNT

FPUT LR / FPNT VALUE OF LOAD RESISTOR
FEXT

JMS I SRT / REQUEST "SCAN RATE"

FIN

FPNT

FPUT SR IFPNT VALUE OF SCAN RATE

FEXT

JMS I AMP / REQUEST
FIN

FPNT

FPUT A / FPNT VALUE OF AMPLITUDE
FEXT

JMS I PST /"POINT SEPARATION"

FIN

FPNT

FPUT PS I FPNT VALUE OF POINT SEP.
FGET A
FDIV PS
FPUT P
FGET PS
FDIV SR
FMPY MTHO

FPUT D IDELAY IN MSEC =(PS/SR)#(1000)
FADD MIN1 / IS DELAY GREATER THAN 1 MSEC
FEXT

TAD 45

SMA
JMP
JMP
JMS
TAD

"AMPLITUDE"

IPTS = AMPLITUDE/POINT SEP.

MSEC I YES: JUMP TO MSEC ROUTINE
USEC / NO: JMP T0 USEC ROUTINE

I SORT ICALCULATE MSEC DELAY

DPT / POINTER TO MSEC DELAY SUB.
DCA DELAY

JMP RTN

FPNT / CALCULATE USEC DELAY

FGET D
FMPY MTHO
FSUB THIRT

ICONVERT MSEC TO USEC

Til-11.1 11 T11 Ill [.1111

0263
0264
0265
0266
0267
0270
0271
0272
0273
0274
0275
0276
0277
0300
0301
0302
0303
0304
0305
0306
0307
0310
0311
0312
0313
0314
0315
0316
0317
0320
0321
0322
0323
0324
0325
0326
0327
0330
0331
0332
0333
0334
0335
0336
0337
0340
0341
0342
0343
0344
0345

4363
6352
1367
0000
4737
7041

3741

1333
3331

1151

3153
4407
5124
0000
4737
3177
1177
7041

3323
1323
3725
4726
6301

5311

4727
4731

2323
5313
4730
4430
5742
0600
0000
2600
1370
0677
0540
1000
0000
0722
0711

0471

0506
0400
4367
0740
0720
1025
0521

0000
0000

RTN:

PUSH:

CONT:

INITL:
PTS:
SORT:
OUPT:
START:
DACL:
DISPY:
DEVAY:
DPT:
DPTU:
SRT:
AMP:
BIAS:
FIX:
TIME:
TU:
SHOW:
PST:
A:

134

FDIV N75

FPUT D

/ DELAY IN MICROSEC.

FADD HALF

FEXT

JMS
CIA
DCA
TAD
DCA
TAD
DCA

FPNT

I FIX

I TU IINSERT IN UDLY SUB.
DPTU

DELAY / POINTER TO USEC DELAY
BUFF / SET UP BUFFER

BUFFPT IFOR DATA STORING

FGET P

FEXT

JMS
DCA
TAD
CIA
DCA
TAD
DCA
JMS

EXSF / LOOK FOR EXPT.

JMP
JMS
JMS
ISZ
JMP
JMS
JMS
JMP
600
0

2600
1370

677
540

1000

0

722
711
471
506
400

4367

740
720

1025

521
0
0

I FIX
177 / STORE NO.
177

OF PTS.

PTS I NO: DATA PTS TO COLLECT
PTS

I OUPT IPTS IN OUTPUT LDC:

I START I PRINT "START EXPT."
STARTING FLAG
0‘1

I DACL / COLLECT DATA PAIR

I DELAY / DELAY UNTIL NEXT

PTS /DATA COLLECTION

CONT

I DISPY / PREPARE FOR DISPLAY

I PRES IOP DATA

I SHOH/ DISPLAY DATA

/ MSEC POINTER

/ UDLY POINTER

/ POINTER FOR MDLY DELAY CONSTANT
I POINTER FOR UDLY DELAY CONSTANT

0346
0347
0350
0351
0352
0353
0354
0355
0356
0357
0360
0361
0362
0363
0364
0365
0366
0367
0370
0371
0372

0400
0401
0402
0403
0404
0405
0406
0407
0410
0411
0412
0413
0414
0415
0416
0417
0420
0421
0422
0423
0424
0425
0426
0427

0000
0000
0000
0000
0000
0000
0000
0012
3740
0000
0004
3300
0000
0003
3600
0000
0563
0000
2146
3146
1150

0000
7300
1244
3245
4424
4421

2305
2440
0211

0123
4100
4430
4232
4424
4421

2305
2440
1116
1124
1456
2017
2456
4100
4430

135

0
PS: 0
0
0
D: 0
0
0
MTHO: 0012 /GREATER THAN 1000
3740 /TO REDUCE ROUNDING ERROR
0000
THIRT: 0004
3300
0000 /1305
N75: 0003
3600
0000 I705
LOADT: 563 /LOAD POINTER
HALF: 0000
2146
3146
CONCT: 1150
I/A'IS’TI

ISEP POLAROGRAPHY INTRO. POT:
ISEP SUBROUTINES BIAS: PRINT:
#400
BIAS: 0
CLA CLL
TAD BUTT
DCA BUTTPT
TYCR
TYMES /
2305
2440
0211
0123
5100
JMS I PRES
JMS SEAD
TYCR
TYMES
2305
2440
1116
1124
1456
2017
2456
4100
JMS I PRES

READ BIAS & INITL:
SRR: AMP: PSS

SET BIAS!

/ SET INITL. POTo!

0430
0431

0432
0433
0434
0435
0436
0437
0440
0441

0442
0443
0444
0445
0446
0447
0450
0451

0452
0453
0454
0455
0456
0457
0460
0461

0462
0463
0464
0465
0466
0467
0470
0471

0472
0473
0474
0475
0476
0477
0500
0501

0502
0503
0504
0505
0506
0507
0510
0511

4232
5600
0000
6543
6532
6531

5235
7300
6534
3645
2245
5632
0100
0000
0000
4424
4426
4421

0500
4426
4426
4421

2516
0356
1100
4426
4426
4421

0317
2256
1100
4424
5646
0000
4424
4421

2303
0116
4022
0124
0540
1526
5723
0503
7200
5671

0000
4424
4421

0115

READ:

BUTT:
BUTTPT:
PRINT:

SRR:

AMP:

136

JMS READ

JMP I BIAS

0 / ROUTINE TO COLLECT DATA
SC2 I SET CHANNEL 2
ADCV / DO ADC CONVERSION
ADSF/ WAIT FOR ADC FLAG
JMP 0-1

CLA CLL

ADRB / READ ADC BUFFER INTO AC
DCA I BUTTPT

ISZ BUTTPT

JMP I READ

100

0

0 / SUBROUTINE T0 TYPE DATA READINGS
TYCR

TYTB

TYMES

0500 / "E"

TYTB

TYTB

TYMES / "UNC. I"

2516

0356

1100

TYTB

TYTB

TYMES

0317 / "COR: P'

2256

1100

TYCR

JMP I PRINT

0 / PRINT ”SCAN RATE"
TYCR

TYMES

2303

0116

4023

0124

0540

1526

5723

0503

7200

JMP I SRR

0 / PRINT ”AMPLITUDE"
TYCR

TYMES

0115

0512
0513
0514
0515
0516
0517
0520
0521
0522
0523
0524
0525
0526
0527
0530
0531
0532
0533
0534
0535
0536

0600
0601

0602
0603
0604
0605
0606
0607
0610
0611

0612
0613
0614
0615
0616
0617
0620
0621

0622
0623
0624
0625
0626

2014
1124
2504
0540
1526
7200
5706
0000
4424
4421
2024
5640
2305
2001
2201
2411
1716
4015
2672
0000
5721

0000
4424
4431
2305
2056
4040
0401
2405
7200
4252
4421
0530
2024
5640
1617
5672
0000
4252
4421
2317
1426
0516
2472

PSS:

I/9-1-70

2014
1124
2504
0540
1526
7200

137

JMP I AMP
0 / PRINT

TYCR

TYMES

2024
5640
2305
2001
2201
2411
1716
4015
2672
0000

JMP I PSS

ISEP SUBROUTINES

/LOAD:

#600

INITL:

UDLY:

MDLY

“PT.

SEPARATION"

INITL: WRITE:START

0 I SUBROUTINE T0 TYPE
TYCR IINITIAL DIALOGUE
/ SEP DATA:

TYMES

2305
2056
4040
0401
2405
7200
JMS

0530
2024
5640
1617
5672
0
JMS

WRITE
TYMES / EXPT.

WRITE

NO:

TYMES / SOLVENT

2317
1426
0516
2472

0627
0630
0631

0632
0633
0634
0635
0636
0637
0640
0641

0642
0643
0644
0645
0646
0647
0650
0651

0652
0653
0654
0655
0656
0657
0660
0661

0662
0663
0664
0665
0666
0667
0670
0671

0672
0673
0674
0675
0676
0677
0700
0701

0702
0703
0704
0705
0706
0707

0000
4252
4421

0514
0503
2422
1714
3124
0572
0000
4252
4421

2205
0103
2401

1624
7200
4252
5600
0000
6032
4261

7300
1276
6046
5253
0000
6031

5262
6036
3276
1276
1275
7450
5273
5661

4424
5652
7563
0000
0000
4424
4421

2324
0122
2440
0530
2024
5600

WRITE:
TYPE:

LISN:

BACK:

CHECK:
STORE:
START:

0
JMS
TYME
0514
0503
2422
1714
3124
0572
0
JMS
TYME
2205
0103
2401
1624
7200
JMS
JMP
0
KCC
JMS
CLA
TAD
TLS
JMP
0 /
KSF
JMP
KRB
DCA
TAD
TAD
SNA
JMP
JMP
TYCR
JMP
7563
0

0
TYCR
TYME
2324
0122
2440
0530
2024
5600

138

WRITE
S I ELECTROLYTE

WRITE
S / REACTANT

WRITE
I INITL

LISN
CLL
STORE

TYPE ITYPE UNTIL CR STRUCK
SUBROUTINE READS KEYBOARD

0‘1

STORE

STORE

CHECK / CHECK IF CR STRUCK

JMP OUT OF SUBROUTINE
CONT: TO READ KEYBOARD

BACK / YES:
I LISN / NO:

I NRITE

S / "START EXPT."

 

0710
0711

0712
0713
0714
0715
0716
0717
0720
0721

0722
0723
0724
0725
0726
0727
0730
0731

0732
0733
0734
0735
0736
0737
0740

0563
0564
0565
0566
0567
0570
0571

0572
0573
0574
0575
0576

0540
0541

0542
0543
0544
0545
0546
0547
0550

5677
0000
7200
1320
3321
2321
5315
5711
0000
0000
0000
1340
3337
7200
1336
6136
6133
5330
2337
S325
7200
5722
0011
0000
0000

0000
4424
4421
1417
0104
4040
2205
2311
2324
1722
7200
5763

0000
6541
4346
6543
4346
5740
0000
6532
6531

139

JMP
a /
CLA
TAD X
DCA TX
ISZ TX
JMP 0‘1 / COUNT DOWN FOR DELAY
JMP I UDLY / RETURN TO PROGRAM
X: 0
TX: 0
MDLY: 0 I
TAD
DCA
CLA
TAD STIM ICLOCK CONSTANT FOR MSEC DELAY
CECL / LOAD AND START CLOCK
CSCF / SEARCH FOR CLOCK FLAG
JMP 0’1
ISZ LOOP / REPEAT SET NUMBER OF LOOPS
JMP CYCL
CLA
JMP I MDLY / RETURN
STIM: 0011
LOOP: 0
TIM: 0
*563
LOAD: 0
TYCR
TYMES
1417
0104
4040
2205
2311
3324
1722
7200
JMP I LOAD

I START

UDNY: MICROSECOND DELAY ROUTINE

ICONSTANT FOR DELAY

MILLISECOND DELAY SUBROUTINE
TIM IDELAY LOOPS TO PROCESS
LOOP

CYCL:

TO MA IN PROGRAM

/ "LOAD RESISTOR "

I/SEP SUBROUTINES DACL AND DISPY FOR BLANKS

I4'6‘71

*540

DACL: 0 / DATA COLLECTTION
SCI / SET CHANNEL 1
JMS COLL
SC2 ISET CHANNEL 2
JMS COU.'
JMP I DACL

COLL: 0

ADCV / ADC CONVERT COMMAND
ADSF / WAIT FOR ADC FLAG

0551
.0552
0553
0554
0555
0556
0557
0560

1000
1001

1002
1003
1004
1005
1006
1007
1010
1011

1012
1013
1014
1015
1016
1017
1020
1021

1022
1023
1024
1025
1026
1027
1030
1031

1032
1033
1034
1035
1036
1037
1040
1041

1042
1043
1044
1045
1046
1047
1050

5350
7300
6534
6211
3553
6201
2153
5746

0000
6557
4424
4421
2305
2440
2520
4033
2240
1106
4002
1124
4060
7561
4005
3011
2440
0411
2320
3100
5600
7200
3323
1151
3153
1177
7041
3324
7200
1323
7040
3333
1323
7450
5252
5244
7200
6211
1553
6552
2153

#1000
DISPY:

SEPT:

CONT:

PDT:

JMP

CLA CLL I CLEAR AC
I READ ADC BUFFER
CDF+10 I CHANGE TO DATA FIELD 1

ADRB

o-I

INTO AC

DCA I BUFFPT I STORE DATA

CDF+00 I CHANGE TO DATA FIELD 0
ISZ BUFFPT
JMP I COLL

0

DACLXY I6557 CLEAR AC & BOTH

TYCR

TYMES I SET UP SR.

2305
2440
2520
4033
2240
1106
4002
1124
4060
7561
4005
3011
2440
0411
2320
3100
JMP
CLA
DCA
TAD
DCA
TAD
CIA
DCA
CLA
TAD
CMA
DCA
TAD
SNA
JMP
JMP
CLA
CDF+

TAD I BUFFPT

DALX

ISZ BUFFPT

I IF BIT 0=1 EXIT DISPY

I DISPY
I DETERMINE LOCATION OF DATA
ZEROPT

BUFF

BUFFPT
177 I PTS

XPTS

ZEROPT I IS DATAM

ZEROPT
ZEROPT

CUR
PDT

I PLOT E ON X AXIS

10

E OR I

1051
1052
1053
1054
1055
1056
1057
1060
1061
1062
1063
1064
1065
1066
1067
1070
1071
1072
1073
1074
1075
1076
1077
1100
1101
1102
1103
1104
1105
1106
1107
1110
1111
1112
1113
1114
1115
1116
1117
1120
1121
1122
1123
1124
1125
1126
1127
1130
1131
1132
1133

5234
7200
1553
6201

6554
2153
4327
2324
5334
7604
7500
5225
4424
4421

1725
2420
2524
4024
3120
0540
5240
0411

0107
5640
2431

2005
5540
7200
4725
1326
7440
5313
4722
5747
1320
7440
5265
4722
5721

7775
2000
1714
0000
0000
2356
7526
0000
7604
7510
5727
7041

CUR:

HELL:

RECK:

M3:

ZEROPT:
XPTS:
TELE:
CHECK:
DELAY:

JMP
CLA
TAD
CDF+

141

CONT

I PLOT I ON Y AXIS
I BUFFPT

00

DALY

ISZ
JMS
ISZ
JMP
LAS
SMA
JMP
TYCS
TYME
1725
2420
2524
4024
3120
0540
5240
0411
0107
5640
2431
2005
5540
7200
JMS
TAD
SZA
JMP
JMS
JMP
TAD
SZA
JMP
JMS
JMP
7775
CRIT
DECI
0

0
2356
7526
0
LAS
SPA
JMP
CIA

BUFFPT

DELAY I CONTROL RATE OF PLOTTING
XPTS

CONT

I IF BIT 0=0£REPEAT3=18CONT.

REPT

S

I TELE
CHECK I -t

RECK

I DECIDE

I OUTPUT I LIST ALL DATA COLLECTED
M3 I -3

WELL IASK AGAIN
I DECIDE I FIND M & B OF BLANK
I CRITT I CALCULATE DIAG. CRITERIA

T: 2000
DE: 1714

/ DELAY CONTROLLED BY SR SETTING

I DELAY

 

1134
1135
1136
1137
1140
1141

1142
1143
1144
1145
1146
1147

1150
1151
1152
1153
1154
1155
1156
1157
1160
1161
1162
1163
1164
1165
1166
1167
1170
1171
1172
1173
1174
1175

1200
1201
1202
1203
1204
1205

3344
1345
3346
2346
5337
2344
5335
5727
0000
7000
0000
1200

0000
4424
4421
1515
1714
0122
4003
1716
7200
5750
0000
7041
3143
2153
2153
6211
1553
6201
3146
1143
1146
5762

7200
3364
4763
4325
1151
3153

LOOP:
CONST:
COUNT:
OUTPUT:

DCA
TAD
DCA
ISZ
JMP
ISZ
JMP
JMP
0
7000
0
1200

II3-22-71

IDATA OUPUT IN FPNT FOR

142

LOOP
CONST
COUNT
COUNT
o-l
LOOP
.-S

I DELAY

SEP EXPT

IUNCORRECTED AND CORRECTED FOR
IBLANK SOLUTION EFFECTS BY LEAST
ISQUARE CORRECTIONS

#1150
CONN:

END:

#1200
OUTPUT:

TYCR

TYME
1515
1714
0122
4003
1716
7200
JMP
0
CIA
DCA
ISZ
ISZ

S IMMOLAR CON:

I CONN

T1
BUFFPT
BUFFPT

CDF+10

TAD

I BUFFPT

CDF+00

DCA
TAD
TAD
JMP

CLA
DCA
JMS
JMS
TAD
DCA

T2
T1
T2
I END

ZEROPT

I FIND I "POTENTIAL CURRENT"
SNITL ILOOK FOR E SHIT.

BUFF ISTORED DATA LOCATION
BUFFPT

1206
1207
1210
1211

1212
1213
1214
1215
1216
1217
1220
1221

1222
1223
1224
1225
1226
1227
1230
1231

1232
1233
1234
1235
1236
1237
1240
1241

1242
1243
1244
1245
1246
1247
1250
1251

1252
1253
1254
1255
1256
1257
1260
1261

1262
1263
1264
1265
1266

4310
1357
3371

1360
3372
1364
7040
3364
1364
7450
5241

5222
4424
4350
4301

4407
6373
3771

1772
6170
5373
1072
3064
0000
4406
2153
5313
4426
4350
4301

4407
2067
4121

6143
0000
4406
1063
7640
5263
4426
4407
5143
2170
0000
4406
2153
1153
1355
7710

CONT:

POT:

CUR:

DOES:

DONT:

143

JMS SET

TAD CPI

DCA A1 I127 FOR MC

TAD CP2 I 132 FOR BC

DCA Bl

TAD ZEROPT IIS DATAM E OR I

CMA

DCA ZEROPT

TAD ZEROPT

SNA

JMP CUR

JMP POT

TYCR ICALCULATE AND OUTPUT POTENTIAL
JMS BRING IDATA FROM FIELD 1

JMS ENTER

FPNT

FPUT Y I FPNT VALUE OF POTENTIAL
FMPY I A1 I LEAST SQUARE CORRECTION
FADD I Bl

FPUT T3 I Y=AX +83 Y=I:X=E

FGET Y

FADD CINPT

FMPY MIN1

FEXT

FOUT

ISZ BUFFPT

JMP CONT

TYTB I CALCULATE AND OUTPUT CURRENT
JMS BRING IEXTRACT DATA FROM FIELD 1
JMS ENTER

FPNT

FSUB CBIAS I SUBTRACT BIAS POTENTIAL
FDIV LR

FPUT T1

FEXT

FOUT I OUTPUT UNCORRECTED CURRENT
TAD 63 IIF 63808BLANK CORRECT

SZA CLA IDOES 63 = 0

JMP DONT INO: DO NOT BLANK CORRECT
TYTB IYES: BLANK CORRECT

FPNT

GGET T1

FSUB T3

FEXT

FOUT ILEAST SQUARE CORRECTED CURRENT
ISZ BUFFPT

TAD BUFFPT

TAD KEEPI

SPA CLA

 

 

1267
1270
1271
1272
1273
1374
1275
1276
1277
1300
1301

1302
1303
1304
1305
1306
1307
1310
1311

1312
1313
1314
1315
1316
1317
1320
1321

1322
1323
1324
1325
1326
1327
1330
1331

1332
1333
1334
1335
1336
1337
1340
1341

1342
1343
1344
1345
1346
1347
1350
1351

5271
5274
2370
5213
5776
1361
3371
1362
3372
5271
0000
4420
4407
4165
3075
0000
5701
0000
1100
4301
4407
6067
0000
1101
4301
4407
2067
6072
0000
5710
0000
1152
3153
4350
4756
7710
5336
1146
5331
7344
1153
7041
3355
1146
4756
7710
5725
1146
5331
0000
6211

HERE:

REPLAC:

ENTER:

SET:

SWITL:

AGAIN:

PLACE:

BRING:

JMP
JMP
ISZ
JMP
JMP
TAD
DCA
TAD
DCA
JMP

144

HERE ICORRECT 1ST USING MC & BC
REPLAC ICORRECT 2ND USING MA & BA
OUPT I TOTAL PTS. COLLECTED

CONT

I CRITT

AP1

A1

AP2 I140 FOR BA

Bl

HERE

0 IBIN DATA TO FPNT POTENTIAL
FCVT I DO BIN TO FPNT CONVERSION

FPNT

FDIV N7 I DIVIDE BY 4096
FMPY EXP I MULTIPLY BY TEN

FEXT

JMP
0

TAD
JMS

FPNT

I ENTER

100 I BIAS
ENTER

FPUT CBIAS

GEXT

TAD
JMS

FPNT

101 I BIAS + INITIAL POTENTIAL
ENTER

FSUB CBIAS
FPUT CINPT

FEXT

JMP
0

TAD
DCA
JMS
JMS
SPA
JMP
TAD
JMP
CLL
TAD
CIA
DCA
TAD
JMS
SPA
JMP
TAD
JMP
0

I SET

BUFF1

BUFFPT

BRING

I ENDT

CLA IIS E2<E1
PLACE IYES

T2 INO

AGAIN

STA RAL ISET AC=~2
BUFFPT

KEEP1

T2

I ENDT ICOMPARE E'S
CLA

I SWITL IYES EL FOUND
T2

AGAIN INO

CDF+10

1352 1553 TAD I BUFFPT

1353 6201 CDF+00

1354 S750 JMP I BRING

1355 0000 KEEPl, 0

1356 1162 ENDT: END

1357 0127 CPI: 127

1360 0132 CP2: 132

1361 0135 AP1: 135

1362 0140 AP2: 140

1363 0446 FIND: 446

1364 0000 ZEROPT. 0

1365 0000 X2. 0

1366 0000 0

1367 0000 0

1370 0000 OUPT: 000

1371 0127 A1. 127

1372 0132 81, 132

1373 0000 Y, 0

1374 0000 0

1375 0000 0

1376 2000 CRITT. 2000
1/4-7-71
IFIND OUT
IPROGRAM TO ASK IF BLANK CORRECTION
ITAPE IS AVAILABLE FOR CORRECTING
IREAL SYSTEM EXPTS.
#1400

1400 4424 IF. TYCR

1401 4421 TYMES / TYPE Y 1F BLANK CORRECTION

1402 2431 2431 ITAPE IS LOADED

1403 2005 2005

1404 4031 4031

1405 4011 4011

1406 0640 0640

1407 0214 0214

1410 0116 0116

1411 1340 1340

1412 0317 0317

1413 2222 2222

1414 0503 0503

1415 2411 2411

1416 1716 1716

1417 4024 4024

1420 0120 0120

1421 0540 0540

1422 1123 1123

1423 4014 4014

1424 1701 1701

1425 0405 0405

 

1426
1427
1430
1431
1432
1433
1434
1435
1436
I437
1440
1441
1442
1443
1444
1445
1446
1447
1450
1451
1452
1453
1454
1455
1456
1457
1460
1461
1462
1463
1464
1465
1466
1467
I470
I471
1472
1473
1474
1475
1476
1477
1500
1501
1502
1503
1504
1505
1506
1507
1510

0440
7200
1367
3770
3774
1375
3776
4772
1365
7650
5251
4424
4421
1617
4000
4342
7240
3063
5766
4424
4421
0214
0116
1340
2303
0116
4022
0124
0540
2201
1607
0540
11H3
7200
4424
4431
2322
4014
7200
4771
4407
6105
0000
4406
4421
4040
1:322
4010
7200
4771
4407

LISN]:

NO:

YES:

LOW:

HIGH:

0440
7200
TAD
DCA
DCA
TAD
DCA
JMS
TAD
SNA
JMP
TYCR
TYME
1617
4000
JMS
STA
DCA

146

CHGT

I CHPTT
I DICOUN
N3000

ISET DIAG COUNTER

I DSET I SET DIAG POINTER

I TELE
CKI I -Y
CLA

YES

5
I NO

CORN
I SET AC
DEED

ICK-

=-1

PT. FOR BLANK CORRECT.

JMP I BEGNT I START EXPT

TYCR

TYMES I SCAN RATE RANGE IS:

0215
0116
1340
2303
0116
4022
0124
0540
2201
1607
0540
1123
7200
TYCR
TYME
2322
4014
7200

JMS I RESTT I OBTAIN FPNT

FPNT
FPUT
FEXT

S I SRL

NO.

IFROM UPPER FIELD

SRL

FOUT I LIST SR L

TYME
4040
2322
4010
7200
JMS

FPNT

S I SR H

I RESTT

 

1511

1512
1513
1514
1515
1516
1517
1520
1521

1522
1533
1524
1525
1526
1527
1530
1531

1532
1533
1534
1535
1536
1537
1540
1541

1542
1543
1544
1545
1546
1547
1550
1551

1552
1553
1554
1555
1556
1557
1560
1561

1562
1563
1564
1565
1566
1567
1570
1571

6110
0000
4406
4421

4040
5734
2322
7200
5771

4407
6113
0000
4406
4424
4421

0214
0116
1300
4773
4771

4406
4424
4342
3063
5766
0000
4421

0214
0116
1340
0317
2222
0503
2411

1716
2340
2711

1414
4002
0540
1501

0405
@000
5742
7447
0200
4000
1615
1600

DELTA:

CONB:

MADE:

CORN:

CKI:

BEGNT:
CHGT:

CHPTT:
RESTT:

147

FPUT SRH
FEXT

FOUT I LIST SR H
TYMES I DSR
4040

5734

2322

7200

JMS I RESTT
FPNT
FPUT DSR
FEXT
FOUT
TYCR
TYMES I BLANK

0214

0116

1300

JMS I CONN

JMS I RESTT

FOUT

TYCR

JMS CORN

DCA DEED ISET 64 = 0 TO BLANK CORRECT
JMP I BEGNT I START EXPT

0000

TYMES

0214 I BLANK CORRECTIONS WILL BE MADE
0116

1340

0317

2222

0503

2411

1716

3340

2711

1414

4002

0540

1501

0405

0000

JMP I CORN

-331

200

4000

1615

1600

I LIST DELTA SR

1572
1573
1574
1575
1576

1600
1601

1602
1603
1604
1605
1606
1607
1610
1611

1612
1613
1614
1615
1616
1617
1620
1621

1622
1623
1624
1625
1626
1637
1630
1631

1632
1633
1634
1635
1636
1637
1640

2356
1150
2567
3000
2564

0000
6211
1615
3044
2215
1615
3045
2215
1615
3046
2215
6201
5600
4000
0000
4407
5116
2105
4113
0000
4712
3310
4276
1313
3215
4200
4424
4421
1503
7200
4407
6127
0000

148

TELE: 2356
CONN: 1150
DICOUN: 2567
N3000: 3000
DSET: 2564
I/3'8'71

IDECIDE PROGRAM:
ITAPE EXISTS:

IF A BLANK M + B
GO LOCATE THE

ICORRECT SLOPES AND INTERCEPTS. IF
INO BLANK CORRECTION TAPE EXISTS:
ICLEAR M + B LOCATIONS IN PAGE 0
IAND NO BLANK CORRECTIONS WILL

IOCCUR.
IFETCH A FPNT.

#1600
RESET:

CHGPT:
LOCATE:

PLACE:

RESET ROUTINE WILL
NO. FROM UPPER FIELD

0000 I FPNT. NO: FROM UPPER FIELD
CDF+10 IAND STORE THE NO: IN FPNT AC
TAD I CHGPT

DCA 44

ISZ CHGPT

TAD I CHGPU

DCA 45

ISZ CHGPT

TAD I CHGPT

DCA 46

ISZ CHGPT

CDF+00

JMP I RESET

4000

0 ILOCATE SLOPE AND
FPNT
FGET
FSUB
FDIV
FEXT
JMS I FIX

DCA B

JMS MULT IFIND DATA SET

TAD CHTT IIST LOCATION OF DATA SETS
DCA CHGPT ILOCATION OF M + B DATA
JMS RESET ITRANSFER DATA INTO FPNT
TYCR

TYMES

1503 I MC:

7200

FPNT

FPUT MC

FEXT

INTERCEPT
SR

SRL
DSR

AC

1641

1642
I643
1644
1645
1646
1647
1650
1651

1652
1653
1654
1655
1656
1657
1660
1661

1662
1663
1664
1665
1666
1667
1670
1671

1672
1673
1674
1675
1676
1677
1700
1701

1702
1703
1704
1705
1706
1707
1710
1711

1712
1713
1714
1715
1716
1717
1720
1721

1722

4406
4200
4424
4421

0203
7200
4407
6132
0000
4406
4200
4424
4421

1501

7200
4407
6135
0000
4406
4200
4424
4421

0201

7200
4407
6140
0000
4406
5616
0000
7300
1307
7041

3311

1310
2311

5303
5676
0014
0000
0000
4367
4014
0000
7200
4734
1063
7700
5332
4407

MULT:

CONT:

N12A:
B:
TALY:
FIX:
CHTT:
DECIDE:

DONT:

FOUT
JMS

TYCR

TYME
0203
7200
FPNT
FPUT
FEXT
FOUT
JMS
TYCR
TYME
1501
7200
FPNT
FPUT
FEXT
FOUT
JMS
TYCR
TYME
0201
7200
FPNT
FPUT
FEXT
FOUT
JMP
0000
CLA
TAD
CIA
DCA
TAD
ISZ
JMP
JMP
14 I
0

0
4367
4014
0
CLA
JMS
TAD
SMA
JMP
FPNT

149

RESET

S/CC:

BC

RESET

5 IMA:

MA

RESEU

S ICA:

BA

I LOCATE

I MULTIPLY 12 BY B TO
CLL IFIND DATA SET
N12A

TALY

B

TALY

CONT

I MULT I ANSWER IN AC
12 DECIMAL

I SETT
DEED I IF=0 :BLANK: ='1:NO BLANK
CLA IIS DEED =-1
DOES I NO
I YES : NO BLANK CORRECTION

1723
1724
1725
1726
1727
1730
1731
1732
I733
1734

2000
2001
2002
2003
2004
2005
2006
2007
2010
2011
2012
2013
2014
2015
2016
2017
2020
2021
2022
2023
2024
2025
2026
2027
2030
2031
2032
2033
2034
2035
2036
2037

5102
6127
6132
6135
6140
0000
5714
4216
5714
1310

7200
1371
3354
7344
3350
1346
3261
1344
3225
1353
3360
1177
7041
3367
1152
3153
6211
2153
7100
1553
1360
763a
5237
2153
2367
5221
1354
3360
1372
3354
5213
1553

DOES:

SETT:

FGET
FPUT
FPUT
FPUT
FPUT
FEXT
JMP

JMS

JMP

1310

150

ZERO
MC
BC
MA
CA

I DECIDE
LOCATE I GO FIND PROPER M + B
I DECIDE

II3-22-71 DIAI

IPEAK RATIO DETECTION

IROUTINE TO FIND IP ANODICIIP CATHODIC
I PROGRAM WILL FIRST FIND IP CATHODIC:

ITHEN

IIP ANODIC

#2000
RATIO:

PUT:

DIAG:

THIS:

LOOK:

CLA
TAD
DCA
CLL
DCA
TAD
DCA
TAD
DCA
TAD
DCA
TAD
CIA
DCA
TAD
DCA
CDF+
ISZ
CLL
TAD
TAD
SZL
JMP
ISZ
ISZ
JMP
TAD
DCA
TAD
DCA
JMP
TAD

CHANGE PARAMETERS AND FIND

CK3

CK2

STA RAL
TWICE
NEG I SMA CLA FOR CATHODIC
HERE

BIG I SZL CLA FOR ANODIC
THIS

CKI I SEARCH ABOVE 4001

CK I COMPARISON FACTOR FOR I
177

ISET AC=-2

PTS

BUFFI ILOCATE DATA BUFFER
BUFFPT

10 I CHANGE DATA FIELD

BUFFPT

ICLEAR LINK FOR ANODIC SEARCH
I BUFFPT

CK I SEARCH I DATA

CLA

LOOK

BUFFPT

PTS

DIAG +1

CK2 I SEARCH ABOVE 3400

CK

CK5

CK2

PUT

I BUFFPT IIST I FOR PEAK DETECTION

2040
2041
2042
2043
2044
2045
2046
2047
2050
2051
2052
2053
2054
2055
2056
2057
2060
2061

2062
2063
2064
2065
2066
2067
2070
2071

2072
2073
2074
2075
2076
2077
2100
2101

2102
2103
2104
2105
2106
2107
2110
2111

2112
2113
2114
2115
2116
2117
2120

6201
4420
4407
6143
0000
2153
2153
6211
1553
6201
4420
4407
6146
1364
2143
0000
1045
7700

5264
5271
4407
5146
6143
0000
5245
7344
1153
3352
2350
5277
5311
1352
3351
2153
1370
3360
1345
3225
1347
3261
5220
6211
1751
6201
4576
4407
2067
4121
6335

COMP:

HERE:

IS]

CDF+00I CHANGE TO DATA FIELD 0

FCVT

FPNT

FPUT T1 ITEMP LOCATION

FEXT

ISZ BUFFPT I SEARCH FOR PEAK CURRENT
ISZ BUFFPT
CDF+10

TAD I BUFFPT
CDF+00

FCVT

FPNT

FPUT T2 I STORE IN TEMP LOCATION

FADD N45 I 45 MV COMPARISON FACTOR
FSUB T1

FEXT

TAD 45 I CONTAINS SIGN OF RESULT

SMA CLA I IS 2ND CURRENT LESS THAN IST

IOBTAIN NEXT I

IHERE IS CHANGED TO SPA CLA FOR ANODIC SEARCH

INOW|.OOKS FOR 2ND CURRENT TO BE GREATER THAN

SWITCH:

STORE:

WAY:

CAMC:

IST
JMP SWITCH I NO: CONTINUE SEARCH FOR PEAK
JMP STORE I YES: STORE PEAK CURRENT

FPNT

FGET T2

FPUT T1

GEXT
JMP

CLL

TAD

DCA

ISZ

JMP

JMP

TAD

DCA

ISZ

TAD

DCA

TAD

DCA

TAD

COMP ISEARCH FOR PEAK CURRENT
STA RAL

BUFFPT IFIND PEAK

NONT I STORE BINARY PEAK CURRENT
TWICE
WAY
CALC
NOWT
IPC I BUFFPT MOC.
BUFFPT

CK4 I SEARCH BELOW 3100

CK

SMALL

THIS

POS

DCA HERE

JMP DIAG

CDF+10 I CALCULATE PEAK CURRENTS
TAD I IPC

CDF+00

JMS I ENTOR I CONVERT ADC READING
FPNT IINTO VOLTAGE

FSUB CBIAS

FDIV LR

FPUT IPCO I 1P CATHODIC

IRESET FOR ANODIC SEARCH
OF IP CATHODIC

2121

2122
2123
2124
2125
2126
2127
2130
2131

2132
2133
2134
2135
2136
2137
2140
2141

2142
2143
2144
2145
2146
2147
2150
2151

2152
2153
2154
2155
2156
2157
2160
2161

2162
2163
2164
2165
2166
2167
2170
2171

2172

0000
6211
1752
6201
4576
4407
2067
4121
6340
0000
5734
2400
0000
0000
0000
0000
0000
0000
7402
7630
7620
7700
7710
7776
0000
0000
3777
4370
0012
3720
0000
4370
0000
0000
0000
0004
2000
0000
0000
4700
4370
4500

ENT:

IPCO:

IAO:

BIG:

SMALL:

NEG:
POS:

UNICE:

IPC:

NOWT:

CKI:
CK2:
MTO:

CK:
V12:

N45:

PTS:
CK4:
CK3:
CKS:

152

FEXT

CDF+10

TAD I NONT
CDF+00

JMS I ENTOR
FPNT

FSUB CBIAS
FDIV LR
FPUT IAO I 1P ANODIC
FEXT

JMP I ENT
2400

SZL CLA
SNL CLA
SMA CLA
SPA CLA

0 I BUFFPT LOCATION OF IP CATHODIC
0 I BUFFPT LOCATION OF IP ANODIC

1746
1747
1750
1751
1752
1753
1754
1755
1756
1757
1760
1761
I762
I763
1764
1765
1766
1767
1770
1771
1772
1773
1774

2200
2201
2202
2203
2204
2205
2206
2207
2210
2311
2212
2213
2214
2215
2216
2217

0000
4424
4421
2417
4022
0524
0111
1640
0211
0123
4001
1604
4011
1624
1456
4020
1724
4024
3120
0540
3140
7200
5746

4424
4421
2417
4001
0393
0520
2440
2431
2005
4001
7200
4356
1337
7650
5331
1351

II3-8-7I

#1746
TAINB:

0000
TYCR
TYME
2417
4022
0524
0111
1640
0211
0123
4001
1604
4011
1624
1456
4020
1724
4024
3120
0540
3140
7200
JMP

153

S
I TO RETAIN BIAS AND
IINITL- POT TYPE Y

I TAINB

IWHAT DO YOU WANT ROUTINE?

IGIVES THE EXPERIMENTER

THE OPTION

ITO ACCEPT OR REJECT A RESULT

IOF IPIV(II2) AND

GIVES THE

IEXPERIMENTER THE CHOICE OF FUTURE
IDATA REDUCTION OPERATIONS BY
IANSWERING TELETYPE INQUIRIES

#2200
WHAT:

TYCR
TYME
2417
4001
0303
0520
2440
2431
2005
4001
7200
JMS
TAD
SNA
JMP
TAD

S
I'TO ACCEPT TYPE A

TELE
CK5
CLA
AOK
COUNT

2220
2221

2222
2223
2224
2225
2226
2227
2230
2231

2232
2233
2234
2235
2236
2237
2240
2241

2242
2243
2244
2245
2246
2247
2250
2251

2252
2253
2254
2255
2256
2257
2260
2261

2262
2263
2264
2265
2266
2267
2270
2271

2272
2273
2274
2275
2276
2277
2300
2301

2302

1367
3351

4424
4421

0617
2240
2205
2005
0124
4024
3120
0540
2200
4424
4421

1605
2740
2422
1101

1440
2431

2005
4016
0000
4424
4421

2201

2405
4013
6240
2431

2005
4013
0000
4424
4421

0411

0107
4020
1417
2440
2431

2005
4004
7200
4356
3342
1342
1343
7650
5346

PEAT:

NEW:

RATE:

DIDE:

LISN:

TAD MI I SET COUNTER TO N-I

154

DCA COUNT

TYCR
TYME

0617 IFOR REPEAT TYPE R

2240
2205
2005
0124
4024
3120
0540
2200
TYCR

TYMES I NEW TRIAL TYPE N

1605
2740
2422
1101
1440
2431
2005
4016
0000
TYCR

S

TYMES I RATE K2 TYPE K

2201
2405
4013
6240
2431
2005
4013
0000
TYCR

TYMES I DIAG PLOT TYPE 0

0411
0107
4020
1417
2440
2431
2005
4004
7200
JMS
DCA
TAD
TAD
SNA
JMP

TELE

STORE I CHARACTER TYPED

STORE

CKI
CLA
REP

I WAS R TYPED

I YES SO REPEAT

2303
2304
2305
2306
2307
2310
2311

2312
2313
2314
2315
2316
2317
2320
2321

2322
3323
2324
2325
2326
2327
2330
2331

2332
2333
2334
2335
2336
2337
2340
2341

2342
2343
2344
2345
2346
2347
2350
2351

2352
2353
2354
2355
2356
2357
2360
2361

2362
2363

1342
1344
7650
5322
1342
1345
7650
5753
1342
1370
7650
5320
5275
4740
5772
4740
4771

4356
1341

7650
5754
5755
4407
5143
1373
6373
0000
5222
7477
2700
7447
0000
7456
7462
7474
2351

5752
5752
0000
0274
2531

0213
0205
0000
6032
6031

5360
6036
6046

YIPE:

PUMP:

AOK:

CK5:
IAVGT:
CK4:
STORE:
CKI:
CK2:
CK3:
REP:

COUNT:
RETNT:
DPMOT:
RESET:
BIGO:
TELE:

TAD
TAD
SNA
JMP
TAD
TAD
SNA
JMP
TAD
TAD
SNA
JMP
JMP
JMS
JMP
JMS
JMS
JMS
TAD
SNA
JMP
JMP
FPNT
FGET
FADD
FPUT
FEXT
JMP
-301
2700
'331
0
'322
-316
'304
ISZ
JMP
JMP
0
274
3531
213
205
0
KCC
KSF
JMP
KRB
TLS

155

STORE I NO CHECK AGAIN

CK2 I WAS N TYPED?

CLA

PUMP ICHANGE BIAS & INITL:
STORE I NO CHECK AGAIN

CK3 I WAS D TYPED?

CLA

I DPLOT I YES SO GO PLOT
STORE I NO

CK6 I WAS K TYPED

CLA

YIPE

LISN I NONE OF ABOVE TYPED
I IAVGT

I LAMGO

I IAVGT

I TAINT

TELE

CK4

CLA

I RESET I JUST DO A NEW
I 8160 IREAD BIAS & INITL:

POT?

TRIAL
POT:

T1
T3T
T3T

PEAT

COUNT
I RETNT
I RETNT

2364
2365
2366
2367
2370
2371
2372
2373
2374
2375

2400
2401

2402
2403
2404
2405
2406
2407
2410
2411

2412
2413
2414
2415
2416
2417
2420
2421

2422
2423
2424
2425
2426
2427
2430
2431

2432
2433
2434
2435
2436
2437
2440

6041
5364
5756
7777
7465
1746
3000
0000
0000
0000

4407
5116
4776
6143
0007
6766
5143
0002
6700
0000
4424
4421
2516
0356
4000
4264
4407
5773
6170
0000
4255
4406
4424
4421
0317
2256
4000
4264
7240
1775
3274
6211
1674

M1:
CK6:

TAINT:
LAMGO:

T3T:

I/4-7-71

156

TSF

JMP O'I
JMP I TELE
-1

'313

1746

3000

0

0

0

DIA2

ICALCULATES IPIV(1I2) UNCORRECTED
IAND CORRECTED FOR CHARGING
ICURRENT AND BLANK EFFECTS

#2400

ENT:

DLIST:

FPNT

FGET SR I FIND VALUE OF SCAN RATE
FDIV I MTO

FPUT T1

FLOG I TAKE LOG

FPUT I LNVT I STORE LOG SR

FGET TI

FSQT
FPUT
FEXT
TYCR
TYMES I UNC.

2516

0356

4000

JMS CPY

FPNT

FGET I IPCT I CATHODIC PEAK CURRENT
FPUT T3

FEXT

JMS CAL

FOUT I OUTPUT UNC.
TYCR

TYMES

0317 ICOR.

2256

4000

JMS CPY

STA

TAD I IPT

DCA NOW I POTENTIAL
CDF+10

TAD I NOW

I V12 I STORE SQUARE ROOT OF SR

IPI(V1I2)

OF IPC

 

2441
2442
2443
2444
2445
2446
2447
2450
2451

2452
2453
2454
2455
2456
2457
2460
2461

2462
2463
2464
2465
2466
2467
2470
2471

2472
2473
2474
2475
2476
2477
2500
2501

2502
2503
2504
2505
2506
2507
2510
2511

2512
2513
2514
2515
2516
2517
2520
2521

2522
“2523
2524

6201

4576
4407
3127
1132
6146
5170
2146
0000
4255
4406
5774
0000
4407
4154
4700
6143
0000
5655
0000
4421

1120
5726
6157
6240
7500
5664
0000
0000
0000
0000
2161

0000
0000
0000
0000
4407
5766
1157
4162
3165
0000
4322
4407
5301

0000
4322
2367
5704
0000
4763
6211

CAL:

CPY:

NOW:
IPP:

V12:
NPP:

DIPUT:

SUB:

157

CDF+00
JMS I ENTOR

FPNT
FMPY
FADD
FPUT
FGET
FSUB
FEXT

I CORRECT FOR CHARGING CURRENT
MC
BC
T2
T3
T2

JMS CAL

FOUT

I OUTPUT COR. IPI(V1I2)

JMP I LNV I GO OUTPUT LN V

0

FPNT
FDIV
FDIV
FPUT
FEXT

CONC I DIVIDE BY CONCENTRATION
I V12 I BY SQUARE ROOT OF SCAN RATE
T1

JMP I CAL

0

TYMES

1120
5726
6157
6240
7500

IIP/(V1I2)

JMP I CPY

0000
FPNT
FGET
FADD
FDIV
FMPY
FEXT

ISTORE BIN N0. FOR DIAG PLOT
I LNVT

N46 I<(LN SR+4:6052)I11-5130>*4095
N11

N7

JMS SUB

FPNT
FGET
FEXT

NPP

JMS SUB

ISZ COUNT I NO. OF

DIAG. PTS

JMP I DIPUT

0 ISTORE BIN N0.

IN FIELD I

JMS I FIX
CDF+10

2525
2526
2527
2530
2531

2532
2533
2534
2535
2536
2537
2540
2541

2542
2543
2544
2545
2546
2547
2550
2551

2552
2553
2554
2555
2556
2557
2560
2561

2562
2563
2564
2565
2566
2567
2570
2571

2572
2573
2574
2575
2576

3764
6201
2364
5722
4772
4430
1367
7041
3371
1365
3364
4354
6552
7200
4354
6554
4770
2371
5340
7604
7700
5333
5762
0000
6211
1764
6201
2364
5754
2322
4367
3000
3000
3213
0000
1127
0000
1000
3135
3200
2151
2155

PLOT:

REP:

FETH:

PUMP:

FIX:
IP:
MAD:

LNVT:
COUNT:
DELAY:
XCOUNT:
DISPY:
IPCT:

LNV:
IPT:
MTO:

DCA
CDF+
ISZ
JMP
JMS
JMS
TAD
CIA
DCA
TAD
DCA
JMS

DALX I PLOT LN V ON

CLA
JMS
DALY
JMS
ISZ
JMP
LAS
SMA
JMP
JMP
0 I
CDF¢
TAD

158

I IP

00

IP

I SUB

I DISPY

I PRES IPREPARE
COUNT

FOR DIAG. PLOT

XCOUNT

MAD

IP

FETH IDIAG PLOTTING

X AXIS

FETH

I PLOT IPI(V1I2) 0N Y AXIS
I DELAY
XCOUNT
REP

I BIT
CLA
PLOT+2
I PUMP
GET BIN N0.
10

I 1P

1=1 TO EXIT DISPLAY

FROM UPPER FIELD

CDF+00

ISZ
JMP
2322
4367
3000
3000
3213
0
1127
0
1000
2135
3200
2151
2155

IP
I FETH

2600
2601

2602
2603
2604
2605
2606
2607
2610
2611

2612
2613
2614
2615
2616
2617
2620
2621

2622
2623
2624
2625
2626
2627
2630
2631

2632
2633
2634
2635
2636
2637
2640
2651

2642
2643

0000
4407
5676
2255
0000
1045
7710
5211
5221
4407
5676
2260
0000
1045
7710
5244
5232
1271
3674
4407
5676
0000
4673
7041
3675
5600
1272
3674
4407
5676
3263
0000
4673
7041
3675
5600

159

II3-9-71

IMSC3

IROUTINE TO DETERMINE PROPER DELAY
ICONSTANTS FOR OBTAINING ACCURATE
IMILLISECOND DELAYS: TWO
ICONSTANTS ARE NECESSARY FOR EACH
IDELAY.

IDELAY STIM
IISEC-40SEC 143
I100MSEC-ISEC 11
I50MSEC-100MSEC 4
IIMSEC-50MSEC 0
#2600
MSECT:

DELAY PER PASS
I0 MSEC

1 MSEC

0.5MSEC
0.1MSEC

0000
FPNT
FGET 1 OT

FSUB N100

FEXT

TAD 45 I IS D GREATER THAN
SPA CLA

JMP NUTHER INO

JMP WOW I YES

FPNT

FGET I DT

FSUB N50

FEXT
TAD
SPA
JMP
JMP
TAD
DCA
FPNT
FGET I DT
FEXT
JMS
CIA
DCA I TIME
JMP I MSECT
TAD N4

DCA I STIM
FPNT

FGET I DT
FMPY N2
FEXT
JMS
CIA
DCA
JMP

I00 MSEC

NUTHER:

45 I IS D GREATER THAN 50 MSEC
CLA

FAST INO

FOUR I YES

N11E

I STIM

WOW:

I FIX

FOUR:

I FIX

I TIME
I MSECT

2644
2645
2646
2647
2650
2651

2652
2653
2654
2655
2656
2657
2660
2661

2662
2663
2664
2665
2666
2667
2670
2671

2672
2673
2674
2675
2676

2700
2701
2702
2703
2704
2705
2706
2707
2710
2711
2712
2713
2714
2715
2716
2717
2720
2721
2722

3674
4407
5676
3266
0000
4673
7041
3675
5600
0007
3100
0000
0006
3100
0000
0002
2000
0000
0004
2400
0000
0011
0004
4367
0736
0740
0352

0000
7200
1721
4420
4407
6143
5727
4143
3324
6722
5102
6727
0000
7001
3721
4733
5700
2351
2501

FAST:

N100:

N50:

N2:

N10:

NIIE:

N4:
FIX:

STIM:
TIME:

DT:

I12-2-70
IIAVGT.
IPROGRAM

*2700
IAVG:

COUNT:

NPP:

160

DCA I STIM

FPNT
FGET
FMPY
FEXT

I DT
N10

JMS I FIX

CIA

DCA I TIME
JMP I MSECT

0007
3100
0000
0006
3100
0000
0002
2000
0000
0004
2400
0000
11

4
4367
736
740
352

TO AVERAGE IP FOR
IENTERING INTO DIAGNOSTIC PLOT

0000
CLA

TAD I COUNT I NO.

FCVT
FPNT
FPUT
FGET
FDIV
FMPY
FPUT
FGET
FPUT
FEXT
IAC

OF TRIALS

T1

I T3T
TI
N20 I MULT: BY 20E6 SCALE FACTOR
I NPP

ZERO

I U3T

IACCUMULATED IPIVII2

DCA I COUNT I RESET COUNTER

JMS I DIPUT I

STORE AVG. DIAG: DATA

JMP I IAVG

2351
2501

2723
2724
2725
2726
2727

2730
2731

2732
2733
2734
2735
2736
2737
2740
2741

2742
2743
2744
2745
2746
2747
2750
2751

2752
3753
2754
2755
2756
2757
2760
2761

2762
2763
2764
2765
2766
2767
2770
2771

2504
0031
2304
5500
2373

7200
3765
4407
5102
6766
6767
6770
6771
6756
0000
4772
4757
3360
1360
1361
7650
5764
1360
1362
7650
5763
5330
2373
2356
0000
7455
7475
2323
1400
3537
3600
3603
3606
3611

161

DIPUT: 2504
N20: 0031
2304
5500
T3T: 2373
ISTAR
I3'II-71

IROUTINE ENTERED FROM MONITOR
ITO DECIDE WHETHER TO START
IEXPERIMENT OR TO CONTINUE
IEXPERIMENT- ROUTINE WILL CLEAR
ICOUNTER: AND CURRENT
ISUMMATION LOCATIONS OF DISP:
IAND PEAK CURRENT AVERAGE

IROUTINE
#2730
START: CMA
DCA I COUNTI
FPNT
FGET ZERO
FPUT I ICOT
FPUT I IAOT
FPUT I ISOT
FPUT I TAUT
FPUT I T33T
FEXT
JMS I TYPEST
JMS I TELE
DCA KEEP
TAD KEEP
TAD CKI
SNA CLA IWAS S TYPED
JMP I BEGIN IYES BEGIN NEW EXPT
TAD KEEP
TAD CK2
SNA CLA IWAS C TYPED
JMP I CONT / YES CONTINUE EXPT
JMP START I NO RESTATE QUESTION
T33T: 2373 IAVERAGE LOC: FOR IP/VI/2
TELE: 2356
KEEP: 0
CKI: “323
CK2: '393
CONT: 2323
BEGIN: 1400
COUNTI: 3537
ICOT: 3600
IAOT: 3603
ISOT: 3606
TAUT: 3611

2772 3754 TYPEST: TYPES
*3754

3754 0000 UYPES: 0000

3755 4424 TYCR

3756 4421 TYMES

3757 2431 TEXT ITY

3760 2005 PE

3761 4023 S

3762 4024 T

3763 1740 O

3764 2324 ST

3765 0122 AR

3766 2440 T

3767 0340 C

3770 2417 TO

3771 4003 C

3772 1716 ON

3773 2411 TI

3774 1625 NU

3775 0540 E

3776 7200 :I

3777 5754 JMP I TYPES
II3-22-71 ELAM
IE LAMBDA SEARCH
IPROGRAM TO SEARCH POTENTIAL
IDATA FOR SWITCHING POTENTIAL
IAND SEARCH CURRENT DATA FOR
/0.85 IP TO LOCATE E ZERO
ITO CALCULATE TAU
*3000

3000 4714 LAMBDA: JMS I SWITL IFIND LOC. OF E SWITCH.

3001 1715 TAD I KEEPT

3002 7041 CIA

3003 3312 DCA ELAMC

3004 7201 CLA IAC

3005 1312 TAD ELAMB

3006 3313 DCA ILAMC

3007 6211 CDF+10

3010 1712 TAD I ELAMB

3011 6201 CDF+00

3012 4576 JMS I ENTOR

3013 4407 FPNT

3014 6307 FPUT EL

3015 0000 FEXT

3016 6211 CDF+10

3017 1713 TAD I [LANE

3020 6201 CDF+00

162

3021
3022
3023
3024
3025
3026
3027
3030
3031
3032
3033
3034
3035
3036
3037
3040
3041
3042
3043
3044
3045
3046
3047
3050
3051
3052
3053
3054
3055
3056
3057
3060
3061
3062
3063
3064
3065
3066
3067
30 70
3071
3072
3073
3074
3075
3076
3077
3100
3101
3102

4576
4407
2067
4121
6304
5716
3323
6173
0000
1152
3153
4275
4576
4407
2067
4121
2173
0000
1045
7710
5234
1317
1153
3153
4275
4576
4407
6146
0000
4730
4407
5307
2146
4116
3727
6320
0000
4424
4673
4406
4674
5726
3372
3335
0000
2153
6211
1553
6201
2153

CONT:

RETURN:

LOCATE:

JMS
FPNT
FSUB
FDIV
FPUT
FGET
FMPY
FPUT
FEXT
TAD
DCA
JMS
JMS
FPNT
FSUB
FDIV
FSUB
FEXT
UAD
SPA
JMP
TAD
TAD
DCA
JMS
JMS
FPNT
FPUT
FEXT
JMS
FPNT
FGET
FSUB
FDIV
FMPY
FPUT
FEXT
TYCR
JMS
FOUT
JMS
JMP
GTAU
THTA
0
ISZ
CDF+
TAD

163

I ENTOR

CBIAS

LS

150

I ICPO

N85

T4 I CURRENT AT E'0

BUFFI
BUFFPT
LOCATE
I ENTOR

CBIAS
LR

T4 I (I - IEO)

45

CLA I IS I GREATER THAN IEO
CONT I N0

M3 I YES SUBTRACT 3 FROM BUFFPT
BUFFPT

BUFFPT

LOCATE

I ENTOR

T2 IE'0
I ESWT

EL

T2

SR I TAU=<E0
I MTO

TAU

‘ EL)ISR

I GTAU

ILIST EXPT.
I THTAT ILIST
I INSRT

: MTAU
T: THTA

TAU
THEORETICAL TAU

BUFFPT
I0
I BUFFPT

CDF+00

ISZ

BUFFPT

3103
3104
3105
3106
3107
3110
3111
3112
3113
3114
3115
3116
3117
3120
3121
3122
3123
3124
3125
3126
3127
3130

3335
3336
3337
3340
3341
3342
3343
3344
3345
3346
3347
3350
3351

3372
3373
3374
3375
3376
3377

5675
0000
0000
0000
0000
0000
0000
0000
0000
1325
1355
2135
7775
0000
0000
0000
0000
3320
2202
3216
2155
3241

0000
4407
5347
4116
0000
4421
3000
4372
4406
5735
0007
3154
1217

0000
4421
4024
0125
7500
5772

ISO:

EL:

ELAMB:
ILAMB:
SWITL:
KEEPT:
ICPO:
M3:
TAU:

N85:

INSRT:
MTO:
ESWT:
*3335
THTA:

CONST:

*3372
MTAU:

164

JMP I LOCATE

88888888

1325
1355
2135
'3

0

0

0
0000
3320
2202
3216
2155
3241

0

FPNT

FGET CONST

FDIV SR ITTAU=4:00(26MV)ISR
FEXT

TYMES IT

3000

JMS MTAU

FOUT

JMP I THTA

0007 I102o76 MV
3154

1217

0

TYMES

4024 ITAU=
0125

7500

JMP I MTAU

 

3200
3201

3202
3203
3204
3205
3206
3207
3210
3211

3212
3213
3214
3215
3216
3217
3220
3221

3222
3223
3224
3225
3226
3227
3230
3231

3232
3233
3234
3235
3236
3237
3240

3241
3242

4424
4421
1416
4026
7500
4407
5313
0000
4406
5612
2200
0000
0000
0000
4407
5634
6143
5635
3064
6146
5636
6170
5637
6173
0000
4640
5633
7600
2135
2140
3104
3120
3400

0000
4424

165

II4-15-71 LNV3

ILNV LISTS

AND INSERT

ILNV FINDS AND LISTS LN V
INSERT

IFOR DIAGNOSTIC OUTPUT.
IFINDS IPCO:

IAO:

ISO:

AND

IINSERTS THEM INTO PAGE 0
IPRIOR TO ENTERING MONITOR FOR
ICALLING IN K2D RATE CONSTANT

IPROGRAM

. ESWIT CALCULATES

ISWITCHING POTENTIAL

*3200

LNV:

ACCEPT:
LNVT:

INSRT:

MONTER:
IPCO:

IAO:
ISO:

TAUT:
DISP:
IESWIT

TYCR

TYMES I LN V=

1546
4026
7500
FPNT
FGET
FEXT
GOUT

LNVU

JMP I ACCEPT

2200
0

0

0

FPNT
FGET
FPUT
FGET
FMPY
FPUT
FGET
FPUT
FGET
FPUT
FEXT

JMS I DISP ILIST I'S AND DECIDE TO ACCEPT

IINSERT CURRENTS INTO PAGE 0

I IPCO

T1

I IAO

MINI
T2

I 150

T3

I TAUT

T4

JMP I MONTER

7600
2135
2140
3104
3120
3400

TAU:

IDSEP ROUTINE TO CALCULATE AND
IVERIFY SWITCHING POTENTIAL TO
IMAINTAIN AtTAU =

ESWIT:

0000
TYCR

AOOO

3243
3244
3245
3246
3247
3250
3251

3252
3253
3254
3255
3256
3257
3260
3261

3262
3263
3264
3265
3266
3267
3270
3271

3272
3273
3274
3275
3276
3277
3300
3301

3302
3303
3304
3305
3306
3307
3310
3311

3312
3313
3314
3315
3316
3317
3320
3321

3322
3323
3324
3325
3326
3327

4421

2431

2005
4031

4011

0640
0540
2327
1124
0310
1116
0740
1526
7500
4407
5146
3721

1325
6330
0000
4406
4426
4723
1324
7650
5641

4424
4421

2305
2440
0540
2327
1124
0310
1116
0740
0116
0440
2205
2005
0124
4005
3020
2456
4100
5722
2155
2323
2356
7447
0007
3154
6315

HUH:

MTHO:
TAINB:
TEME:

CKI:

NIOZ:

166

TYMES ITYPE Y IF E

2431
2005
4031
4011
0640
0540
3327
1124
0310
1116
0740
1526
7500
FPNT
FGET
FMPY
FADD
FPUT
FEXT
FOUT
TYTB

ISWITCHING MV =

T2 I E10

I MTHO ICONVERT TO MV
N102 I 102:8 MV

ESW

JMS I TELE
TAD CKI

SNA CLA
JMP I ESWIT IYES:

TYCR

IWAS Y TYPED?
CALCULATE K2
INO

TYMES ISET E SWITCHING

2305
2440
0540
2327
1124
0310
1116
0740
0116
0440
2205
2005
0124
4005
3020
2456
4100

IAND REPEAT EXPT

JMP I TAINC

2155
2323
2356
~33I
0007
3154
6315

3330
3331
3332

3352
3353
3354
3355
3356
3357
3360
3361
3362
3363
3364
3365
3366
3367
3370
3371

3132
3133
3134
3135
3136

3137
3140
3141
3142
3143
3144
3155
3146

3147
3150
3151

0000
0000
0000

0000
4424
4421
2410
0516
4040
2022
0523
2340
0317
1624
1116
2505
4100
7402
5752

0000
4424
4421
1103
7500

4407
5143
0000
4406
4425
4431
1101
7500

4407
5146
0000

167

ESW:

888

I3-9-71
#3353
PRESS: 0000
TYCR
TYMES
2410
0516
404a
2022
0523
2340
0317
1624
1116
2505
4100
HLT
JMP I PRESS

ITHEN PRESS CONTINUE

II4-I4-71 DISP

IWILL LIST ICO: IAO: I50: ASK

IIF ACCEPTABLE AND IF OK WILL

ISUM AND STORE THE CURRENTS AND
ITAU. WHEN K2D RATES ARE DESIRED
IPROGRAM WILL AVERAGE THE CURRENTS
IAND TAU: STORE THE RESULTS ON
IPAGE ZERO AND JUMP TO MONITOR.
IBLANK CORRECTIONS WILL BE MADE
IIF DESIRED.

#3132
LIST: 0 ILIST IC:
TYCR

TYMES

IIC

IA: IS

TEXT
=I

FPNT
FGET TI
FEXT
FOUT
TYSP
TYMES

TEXT IIA

FPNT
FGET T2
FEXT

3152
3153
3154
3155
3156

3157

3160
3161
3162
3163

3400
3401

3402
3403
3404
3405
3406
3407
3410
3411

3412
3413
3414
3415
3416
3417
3420
3421

3422
3433
3424
3425
3426
3427
3430
3431

3432
3433
3434
3435
3436
3437
3440
3441

3442
3443
3444
3445
3446

4406
4425
4421
1123
7500

4407

5170
0000
4406
5732

0000
4731

1063
7710
5252
7240
1751

3153
4744
4745
4407
5143
2747
6143
0000
7240
1742
3153
4744
4746
4407
5146
1747
6146
0000
1743
3153
4744
4745
4407
5170
2747
6170
0000
4744
4746
4407
5170
2747

TEXT

#3400
DISP:

WNDR:

ANND:

FOUT
TYSP
TYME
IIS

FPNT
FGET
FEXT
FOUT
JMP

00
JMS
TAD
SPA
JMP
STA
TAD
DCA
JMS
JMS
FPNT
FGET
FSUB
FPUT
FEXT
STA
TAD
DCA
JMS
JMS
FPNT
FGET
FADD
FPUT
FEXT
TAD
DCA
JMS
JMS
FPNT
FGET
FSUB
FPUT
FEXT
JMS
JMS
FPNT
FGET
FSUB

168

S

T3

I LIST

I LISTT

DEED IIS BLANK CORRECTION THERE
CLA IIS DECD = 0

NEXT INO: NO BLANK CORRECTION

I YES: BLANK CORRECTION DESIRED

I EPT IBUFFER LOC. OF IPC

BUFFPT

I ROUT1T ICALCULATE FPNT POTENTIAL
I ROUT2T ICATHODIC CORRECTION

1.

T1
I TST
T1 IICO

I EAT I BUFF LOC. OF 1A0
BUFFPT

I ROUT1T

I ROUT3T I ANODIC CORRECTION

T2

I T5T

T2LIIA0

I ELT OF E SWITCHING
BUFFPT
I ROUT1T
I ROUT2T

IBUFF LOC.

T3
I T5T
T3 IISO

ICORRECT I50 BOTH
IFOR CATHODIC AND FOR
CHARGING

I ROUUIT
I ROUT3T
IANODIC
T3
I T5T

3447
3450
3451

3452
3453
3454
3455
3456
3457
3460
3461

3462
3463
3464
3465
3466
3467
3470
3471

3472
3473
3474
3475
3476
3477
3500
3501

3502
3503
3504
3505
3506
3507
3510
3511

3512
3513
3514
3515
3516
3517
3520
3531

3522
3533
3524
3525
3526
3527

6170
0000
4731
4732
4735
1340
7650
5260
5277
2337
4407
5143
1751
6751
5146
1752
6752
5170
1753
6753
5173
1754
6754
0000
4734
4735
1340
7650
5306
4755
5736
1337
4420
4407
6750
5751
4750
6143
5752
4750
6146
5753
4750
6170
5754
4750
6173
0000
4733

NEXT:

OK:

HERE:

AVGG:

SHOOT:

FPUT
FEXT
JMS
JMS
JMS
TAD
SNA
JMP
JMP
ISZ
FPNT
FGET
FADD
FPUT
FGET
FADD
FPUT
FGET
FADD
FPUT
FGET
FADD
FPUT
FEXT
JMS
JMS
TAD
SNA
JMP
JMS
JMP
TAD
FCVT
FPNT
FPUT
FGET
FDIV
FPUT
FGET
FDIV
FPUT
FGET
FDIV
FPUT
FGET
FDIV
FPUT
FEXT
JMS

169

T3

I LISTT

I IFT IACCEPT MESSAGE

I TELE

CK2

CLA I WAS A TYPED

OK I YES SUM THE CURRENTS

HERE INO: REJECT PREVIOUS TRIAL
COUNT I NUMBER OF TRIALS

T1

I IC ISUMM EACH CURRENT
I IC IAND STORE FOR AVERAGE
T2

I IA

I IA

T3

I IS

I IS

T4

I TAUT

I TAUT

I IAVT
I TELE

CK3

CLA IWAS A TYPED

AVGG IYES GO AVERAGE

I REPT

I RTURN I NO RETURN TO SEP

COUNT IAVERAGE CURRENTS AND
ION PAGE ZERO FOR K2 CALC.

IAVERAGE ? MESSAGE

STORE

“
Z1~ Zh~Z
In D O

U

HouhndruhnHr-hnCruhnH
A)
2'4 21—
D
C
4

b

I KICK IMESSAGE TO CALL IN K2D

 

 

3530
3531
3532
3533
3534
3535
3536
3537
3540
3541
3542
3543
3544
3545
3546
3547
3550
3551
3552
3553
3554
3555

3600
3601
3602
3603
3604
3605
3606
3607
3610
3611
3612
3613
3614
3615
3616
3617
3620
3621
3622
3623
3624
3625
3626
3627
3630
3631
3632

5600
3132
3643
3665
3711

2356
0274
0000
7477
2151

3152
3112
3617
3625
3634
3735
3614
3600
3603
3606
3611

3740

0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
0000
6211
1553
6201
4576
5617
0000
4407
3127
1132
6335
0000

LISTT:

IFT:

KICK:
IAVT:
TELE:
RTURN:
COUNT:

CK2:
EPT:
EAT:
ELT:

ROUT1T:
ROUT2T:
SOUT3T:

TST:
N:
IC:
IA:
IS:

TAUT:
REPT:
*36OO

ICO:

IAO:

ISO:

TAU:

NT:

ROUTI:

ROUT2:

170

JMP I DISP

LIST
IF
KIC
IAV
2356
274
0
-301
2151
2152
3112

ROUTI
ROUT2
SOUT3

T5
NT
ICO
IAO
ISO
TAU
REPM

8888888888888888

CDF+10
TAD I BUFFPT
CDF+00

JMS I ENTOR ICALC.

FPNT POT.

JMP I ROUTI

0

FPNT
FMPY
FADD
FPUT
FEXT

MC
BC IBLANK CORRECTION
T5

 

3633
3634
3635
3636
3637
3640
3641
3642
3643
3644
3645
3646
3647
3650
3651
3652
3653
3654
3655
3656
3657
3660
3661
3662
3663

3664
3665
3666
3667
3670
3671
3672
3673
3674
3675
3676
3677
3700
3701
3702
3703
3704
3705
3706
3707

3710
3711
3712

5625
0000
4407
3135
1140
6335
0000
5634
0000
4424
4421
2417
4001
0303
0520
2440
0325
2222
0516
2433
4024
3120
0540
0172
0000

5643
0000
4424
4431
0617
2240
0411
2320
1722
5640
2431
2005
4013
6204
4001
0624
0522
4056
4041
0000

5665
0000
4424

171

JMP I ROUT2

ROUT3: O
FPNT
FMPY MA
FADD BA
FPUT T5
FEXT
JMP I ROUT3
IF: O
TYCR
TYMES
TEXT ITO
A
CC
EP
T
CU
RR
EN
TS
T
YP
E
/
JMP I IE
KIC: O
TYCR
TYMES
TEXT IFO
R
DI
SP
OS
TY
PE
K
2D
A
FT
ES
I
/
JMP I KIC
IAV: O

TYCR

SW
1
i

___.1.1‘

3713
3714
3715
3716
3717
3720
3721
3722
3723
3724
3735
3726
3727
3730
3731
3732
3733

3734
3735
3736
3737
3740
3741
3742
3743
3744
3745
3746
3747
3750
3751

3752

4000
4001
4002
4003

4421
2417
4001
2605
2201
0705
4001
1604
4006
1116
0440
1362
4024
3120
0540
0172
0000

5711

0000
0000
0000
0000
4424
4431

2205
2005
0124
4095
3020
2456
4100

5740

0000
3231
1231
7100

172

TYMES
TEXT ITO
A
VE
RA
GE
A
ND
P
IN
D
K2
T
YP
E
A:
/
JMP I IAV
T5: O
O
O
REPM: O
TYCR
TYMES
TEXT IRE
PE
AT
E
XP
T.
II
JMP I REPM
IFCVT

ITHE FOLLOWING IS A SUBROUTINE THAT WILL
ICONVERT A 12 BIT ZBINARY WORD TO FLOATING
IPOINT FORMAT FROM 0 (0000)-OCTAL) TO
I4095 (7777)

ITHE WORD TO BE CONVERTED MUST BE IN

ITHE ACCUMULATOR: THEN EXECUTE "JMS 4000":
IRESULT IS CONTAINED IN THE FLOATING
IPOINT ACCUMULATOR.

#4000

FLT: O
DCA TEMP
TAD TEMP

CLL

 

4004
4005
4006
4007
4010
4011

4012
4013
4014
4015
4016
4017
4020
4021

4022
4023
4024
4025
4026
4027
4030
4031

4032
4033
4034
4035
4036
4037
4040
4041

4367
4370
4371
4372
4373
4374
4375
4376
4377

7004
7430
5217
7200
1231
3233
4635
5232
7000
0000
5600
7200
1231
0236
3233
4635
5232
7000
1237
0000
5600
0000
0013
0000
0000
5600
3777
0014
2000
0000

0000
4407
1375
0000
1046
5767
0027
2000
0000

173

RAL
SZL I IF NEG NO.: GO TO FIXX
JMP FIXX
CLA
TAD TEMP
DCA FLTC+1
JMS I FPP
FGET FLTC
FNOR
FEXT IRESULT IN FPNT ACC.
JMP I FLT
FIXX: CMA
TAD TEMP
AND MASK IMAKE NO. POSITIVE
DCA FLTC+1
JMS I FPP
FGET FLTC
FNOR
FADD F2048
FEXT
JMP I FLT
TEMP: 0
FLTC: 0013
0000
0000
FPP: 5600

MASK: 3777
F2048: 0014
2000
0000

IFIX

IROUTINE TO CONVERT FLOATING PT.
INUMBER TO AN INTEGER.

INUMBER IN FLOATING AC IS TRUNCATED
IAND RESULT LEFT IN AC. FLOATING NO.
IMUST BE IN RANGE 0 TO 4:095 (10).
IEXAMPLE: "FIXING" 4:095o9876 IN
IFLOATING AC: LEAVES 7777 (8) IN AC
ION RETURN FROM JMS FIX.

#4367 ILINE IS
PIX: O

FPNT

FADD FIXC

FEXT

TAD 46

JMP I FIX
FIXC: 0027

ZOOO

OOOO

P1117

0200
0201

0202
0203
0204
0205
0206
0207
0210
0211

0212
0213
0214
0215
0216
0217
0220
0221

0222
0223
0224
0225
0226
0227
0230
0231

0232
0233
0234
0235
0236
0237
0240
0241

0242
0243
0244
0245
0246

4773
3371
4407
5143
6334
5146
4334
6143
5170
4334
0001
3337
1143
6143
5170
4334
3345
1342
1143
6143
0000
4406
4772
4424
4421
4040
4040
6000
4426
4426
4426
4407
5143
3350
6143
0000
4756
3357
1360

174

II4-16-71

IK2D: SEMI

IASSUMES A.TAU=4.00
ISEMI-EMPERICAL DETERMINATION

IOF PEAK CURRENT RATIO FOR THE
IDISPROPORTIONATION MECHANISM AND
IA DATA TABLE SEARCH FOR CALCULATING
IK2 RATE CONSTANTS FOR 5 SPHBfICITY
IFACTORS
*200
SEMI: JMS I TELL ITYPE IAIIC =

DCA COUNT I SET COUNTER TO 0

FPNT

FGET T1

FPUT ICOT

FGET T2 I 1A0

FDIV ICOT

FPUT T1 IIAIIC=IAOIICO + B(ISOIICO)?2
FGET T3 I + G(ISOIICO) + E

FDIV ICOU

FSQR

FMPY B

FADD T1

FPUT T1

FGET T3 I 150

FDIV ICOT

FMPY G

FADD E

FADD T1

FPUT T1

FEXT

FOUT

JMS I SPHER I TYPE SPHERICITY K2
TYCR

TYMES I0

4040

4040

6000

TYTB

TYTB

TYTB

FPNT

FGET T1

FMPY MTHO

FPUT T1

FEXT

JMS I FIX

DCA RATIO I BIN VALUE OF IAIIC

TAD IBUFI ITO SEARCH TABLE

 

0247
0250
0251
0252
0253
0254
0255
0256
0257
0260
0261

0262
0263
0264
0265
0266
0267
0270
0271

0272
0273
0274
0275
0276
0277
0300
0301

0302
0303
0304
0305
0306
0307
0310
0311

0312
0313
0314
0315
0316
0317
0320
0321

0322
0323
0324
0325
0326

3361

1761
7041
1357
7700
5260
2361

2361

5250
2361
1761

4420
4407
4353
6362
4154
4173
6365
3350
0000
4406
2371

1371

1322
7650
5727
1371
1323
7650
5730
1371
1324
7650
5731

1371

1325
7650
5732
1371

1326
7650
5770
7402
7777
7776
7775
7774
7773

SESCH:

FIND:

WONDER:

CKI:
CK2:
CK3:
CK4:
CK5:

175

IBUFT

I IBUFT I SEARCH TABLE OF
IIAIIC VS W WHERE
RATIO IW = K2CO*TAU
CLA

FIND

IBUFT

IBUFT

SESCH

IBUFT

I IBUFT I W

N100 I100
WT

CONC
T4 I
K2T

MTHO

I CALCULATE K2
TAU

ICONVERT MM TO MOLAR

COUNT I DETERMINE WHICH
COUNT ISPERICITY TABLE
CKI I-1

CLA I IS COUNT=1

I REPI IYES

COUNT

CK2 I-2

CLA I IS COUNT=2

I REP2 IYES

COUNT

CK3

CLA I IS COUNT=3

I REP3 IYES

COUNT

CK4 I-4

CLA IIS COUNT=4

I REP4 IYES

COUNT

CK5

CLA I IS COUNT=5

I TURN I YES 3 DONE
I NO: ERROR

0337
0330
0331

0332
0333
0334
0335
0336
0337
0340
0341

0342
0343
0344
0345
0346
0347
0350
0351

0352
0353
0354
0355
0356
0357
0360
0361

0362
0363
0364
0365
0366
0367
0370
0371

0372
0373

0420
0433
0446
0461

0000
0004
2406
3146
0001

2425
4021

7777
3605
0753
0000
4164
5706
0012
3720
0000
0007
3100
0000
4367
0000
2000
0000
0000
0000
0000
0000
0000
0000
0600
0000
0400
0535

REPI:
REP2:
REPS:
SEPA:
BLANK:
ICOT:

B:

E:

G:

MTHO:

NIOO:

FIX:
RATIO:
IBUPI:
IBUFT:
WT:

K2T:

TURN:
COUNT:
SPHER:
TELL:

420
433
446
461
0
0004
2406
3146
0001
2425
4021
7777
3605
0753
0000
4164
5706
0012
3720
0000
0007
3100
0000
4367

2000

00

8138888888

400
525

176

IIOOOS UA

I1.271

I0.470

0400
0401

0402
0403
0404
0405
0406
0407
0410
0411

0412
0413
0414
0415
0416
0417
0420
0421

0422
0423
0424
0425
0426
0437
0430
0531

0432
0433
0434
0435
0436
0437
0440
0441

0442
0443
0444
0445
0446
0447
0450
0451

0452
0553
0454

0000
4424
4421

2320
1005
2211
0311
2431

0000
4426
4426
4426
4421

1362
0000
5600
4424
4421

4066
5662
6500
4426
4426
4426
1274
3701

5700
4424
4421

4062
6556
6000
4426
4426
4426
1275
3701

5700
4424
4421

6566
5662
6500
4426
4426

177

I12-7-70 SPHR

IMESSAGES FOR DISPROPORTIONATION

IRATE CONSTANT PROGRAM

#400

SPHER:

REPI:

REP2:

REPS:

0

TYCR

TYMES I SPHERICITY
1:320

1005

2211

0311

2431

0000

TYTB

TYTB

TYTB

TYMES I K2
1362

0000

JMP I SPHER
TYCR

TYMES

4066 I 6.25
5662

6500

TYTB

TYTB

TYTB

TAD IBUF2
DCA I IBUFTT
JMP I SERCHT
TYCR

TYMES I 25.0
4062

6556

6000

TYTB

TYTB

TYTB

TAD IBUF3
DCA I IBUFTT
JMP I SERCHT
TYCR

TYMES

6566 I 56.35
5662

6500

TYTB

TYTB

 

0455
0456
0457
0460
0461
0462
0463
0464
0465
0466
0467
0470
0471
0472
0473
0474
0475
0476
0477
0500
0501

0600
0601

0602
0603
0604
0605
0606
0607
0610
0611

0612
0613
0614
0615
0616
0617
0620
0621

0622
0623
0624
0625
0626
0627
0630
0631

0632

4426
1276
3701
5700
4424
4421
6160
6056
6000
4426
4426
4426
1277
3701
5700
2230
2435
2640
3045
0250
0361

4424
4421
2431
2005
4047
0423
0520
4740
0106
2405
2240
4756
4740
2417
4022
0524
2522
1640
2417
4023
0520
4020
2217
0722
0115
4041
4000

178

TYTB
TAD IBUFA
DCA I IBUETT
JMP I SESCHT
REP4: TYCR
TYMES I 100.0
6160
6056
6000
TYTB
TYTB
TYTB
TAD IBUFS
DCA I IBUFTT
JMP I SERCHT
IBUFQ: 2230
IBUES: 2435
IBUFA: 264O
IEUFS: 3045
SESCHT: 25O
IBUFTT: 361
II’ZI'TI K2D MESSAGE ROUTINE
*6OO
TURN: TYCR
TYMES
TEXT ITY
PE

05
EP
0
AF
TE
R

T0
R
ET
UR
N
TO
5
EP
P
R0
GR
AM
1
/

0633
0634

0525
0526
0527
0530
0531
0532
0533
0534
0535
0536
0537
0540
0541
0542
0543
0544
0545
0546
0547
0550

5634
7600

0000
4424
4421
0411
2320
2217
2017
2224
1117
1601
2411
1716
7200
4424
4421
1101
5711
0340
7500
5725

179

JMP I MONT /RETURN TO MONITDT
MONT: 76OO
/I'6'7I
/K2D MESSAGE ROUTINE
*535
TELL: O

TYCR

TYMES /DISPROPORTIONATION

O411

232O

2217

2OIT

2224

1117

I6OI

2411

17I6

72OO

TYCR

TYMES

IIOI / IAIIC =

5711

O34O

TSOO

JMP I TELL

WTNIHWINHHSIWITHTU “11111115111111 1111111“
3 1193 03012 6238