Chapter 2 (U) The First Electronic Corputer: Perhaps

\(U) A Reminder of Hooper\'s Hopes and Frustrations

\(U) The development of new cipher machines and the maturation of radio

led to a critical data problem for America\'s cryptanalysts. There was

more and more data, and it was overwhelming those who were charged with

turning it into useful information for policymakers. The failure to

predict the attack on Pearl Harbor, for example, was the result of too

much data. The thousands of intercepted Japanese naval messages could

not be analyzed with the men and equipment available to Laurance

Safford\'s OP-20-G. 1

\(U) Vannevar Bush realized the similarity between the challenges facing

the cryptanalysts and the ones faced by those who were trying to reform

the way the nation handled scientific information. He believed the two

groups could share technology and methods. Captain Stanford C. Hooper

might not have been aware of the trends in scientific literature, but he

was certainly frightened by increasingly sophisticated cipher machines

being introduced by potential enemies. That was what led him and his

protege, Joseph Wenger, to Bush in late 1935.2 Despite Hooper\'s vision

and Wenger\'s efforts, OP-20-G began World War II without any operating

high-speed devices. The Rapid Analytical Machine project had to begin

over again in 1942 and in conditions ill-suited to long-term

development.

\(U) The reasons for the failure of Hooper\'s 1930s plans for the

application of scientific/mathematical methods tocodebreaking are

complex. Bureaucratic tangles, bad luck, personality clashes, Bush\'s

stubbornness, international crises, and the intransigence of technology

partially account for the lost opportunity. But the major factor was

institutional. Above all else,

the military had not yet placed great faith in the kind of information

that cryptanalysis or other signals intelligence could provide. 3

\(U) The Institutional Context

\(U) By the mid-1980s, Hooper and his admiring young officers feared that

America would be dragged into a war while Naval Communications was

unprepared for a face-off with any power. Hooper\'s 1930s strategy, to

collaborate with universities and corporate centers, was an attempt to

compensate for the lack of money needed to prepare for a modern war. The

Chief of Naval Operations supported his plans, but the CNO approval did

not mean smooth sailing for Hooper and his men. To Hooper\'s regret,

OP-20-G continued to have to depend on the Bureau of Engineering because

navy law and \"G\'s\" pauper budgets allowed little else. More

independence and money might have come to OP-20-G if there had been

widespread faith in signals intelligence. But despite the contributions

of Herbert Yardley\'s Black Chamber during the 1920s, then OP-20-G\'s

penetration of Japanese naval codes, and then the cracking of Japan\'s

diplomatic messages, codebreaking remained a stepchild of the American

military. 4 Ironically, the reading of the Japanese naval and diplomatic

code and cipher systems during the 1920s and 1930s masked the need for

the long-term programs required for the development of advanced methods

and machines. Even the navy\'s operating cryptanalysts did not lobby for

such a program.5 Only two men, Hooper and Wenger, saw the need and were

willing to suffer the possible career penalties imposed on those who

became advocates for unpopular causes.

\(U) Hooper and Wenger had never abandoned their 1930 hopes for machines

that would

be much more advanced than the tabulators.6 In late January 1936, Wenger

met with Bush and discussed OP-20-G\'s hopes and problems.7 Bush

presented Wenger with a handwritten eight-page outline of his plan for

automating OP-20-G\'s cryptanalytic section.8 Within a week, Wenger had

secured the new Director of Naval Communications\'s approval of the

proposed relationship with Bush.

\(U) TJie First Defeat; Bush Is Rejected

\(U) Just as Wenger proudly submitted his own visionary outline for the

reorganization of OP-20-G, he received a slap in the face. The Bureau of

Engineering refused to approve the agreement with Vannevar Bush! 9 There

was reason for the bureau\'s alienation. What Bush demanded and what

Hooper and Wenger agreed to were startling. Bush demanded having the

government pay the bill while he remained free of supervision. He wanted

the relationship with the navy to match the ideal relationship between

university researchers and major private foundations. The researcher

would submit a general proposal and then be funded without any

interference from the grantor. Following on his beliefs, Bush had

refused to sign a typical navy contract or to make any promises about

the results of his work.

\(U) In addition, the original understanding did not include a promise to

construct any machinery. Bush and Wenger had also agreed to ignore the

regulations demanding competitive bidding on naval contracts. In

addition, Bush requested what was an enormous amount of money in the

era, at least for the navy. To hire Bush meant taking precious resources

from the bureau and from OP-20-G.

\(U) A Machine Too Soon

\(U) There were also serious technical objections. Although only the

barest sketch, Bush\'s early 1936 proposal showed that he wanted the

navy to use optical scanning, high-speed data tapes, electronic

computing, and microfilm in a series of increasingly complex

cryptanalytic machines. Such technologies, Bush emphasized, would allow

processing speeds from ten to one hundred times faster than the

tabulators. Engineering thought that his recommendations were

speculative and liable to be very costly failures. Engineering\'s staff

had good reason to be worried about the technical ideas. The core

technologies Bush recommended were, to significant degrees, still

experimental.

\(U) Also, the bureau\'s engineers claimed they had their own solution to

the problem of automatic cipher machines. They were reluctant to give

Wenger even a hint of their approach, however.10 Whatever its secret

alternative to Bush\'s proposals, engineering had accepted the

tabulator. It was an off-the-shelf technology that had a stable

manufacturer. IBM knew the ropes of government contracting and was

investing in ongoing development with its own funds. Many of

engineering\'s men were already creating significant and clever

modifications to IBM\'s machines, making them more effective

cryptanalytic tools.

\(U) In addition, the views of OP-20-G\'s cryptanalysts were not

incomplete harmony with Wenger\'s. The operational cryptanalysts

wondered who could steal the time to devise the new procedures necessary

to make such strange technology useful. By the mid-i930s, Laurance

Safford and Jack Holtwick became more allies than enemies of Hooper\'s

long-term plans, but the remainder of the staff were willing to join

with engineering in seriously questioning the value of Bush\'s

machines.\" All the objections and emotions meant that by mid-1936 the

attempt to bring electronics to American cryptanalysis was deadlocked,

if not defeated. But Stanford Hooper, Vannevar Bush, and Joseph Wenger

collected the needed political support, drew up a new plan, and

outflanked the bureau and the conservative cryptanalysts.

\(U) Hooper and Wenger developed anew strategy to surmount any remaining

objections. To placate the engineers, Hooper agreed to ask Bush to

submit a more detailed and specific proposal. The new Bush proposal was

submitted to a special research group in the navy rather than to

engineering. In September 1936, within a week after he received the new

plan, Hooper reported to Bush that the prestigious research board had

approved his project. Wenger and Bush developed compromise positions on

the bureaucratic and legal objections, then presented the new proposal

to engineering. The bureau gave in, but it took almost all of October

and November 1936 to draft an acceptable contract.

\(U) Under 1937\'s formal contract, Bush agreed to focus on the details

of a particular device so that engineering could have something

concrete. He was to submit four reports, each detailing a major

component of the proposed machine. The commitment to details and the

year and one-half time limit for delivery of all the reports helped to

satisfy the bureau\'s demand for a scheduled product. 12

\(U) The Decision to Build a Machine

\(U) Bush had become attached to Wenger and Hooper, and their pleas

convinced him to make a gentleman\'s promise that he soon regretted. He

told them he would try to build a machine, and if he succeeded he would

give it to the navy at no additional cost, except for shipping charges

for the finished machine.13 It had become very important to Wenger to

have a device. To ensure that his project would not die when Bush\'s

contract ended, Wenger needed a machine to prove that photoelectronics

was practical.

\(U) Bush was not sure that he could build a machine in time, but in

early 1937 he was absolutely sure of one thing: MFTs work for OP20-G

would be cut off by mid-1938 when the contract with the bureau

terminated. During the year of bickering with the navy, Bush became

involved

in an increasing number of projects that were critical to the

Institute\'s planned analysis center and his career. One consequence was

that the navy\'s project became more of a burden than an opportunity.

\(U) Bush spent much time on the initial designs for an astounding

general-purpose electronic digital computer. He sent his students and

colleagues the first of several outlines of the proposed digital device,

soon to be called the Rapid Arithmetical Machine, in January 1937.14 In

the three years after the first contacts with the navy, Bush and his men

had put all the years of struggle behind them. Bush had his \"boys\"

immersed in three highly innovative digital projects: the electronic

Rockefeller Analyser; the electronic, programmable Rapid Arithmetic

Machine; and the Rapid Selector.

\(U) Bush and Wenger Select a Problem

\(U) Bush consulted with Joseph Wenger and opted for a device to help

OP-20-G apply the latest statistical techniques to the cipher

problems.15 Bush knew that if a machine was built, it had to be one that

was reliable enough to convince the bureau to fund a long-term RAM

project. Furthermore, Bush knew that any machine he created would have

to outperform OP-20-G\'s tabulators and the special mechanical devices

l6 that had become so dear to many of its staff. His machine had to be

much faster than the electromechanical devices. 17

\(U) There were many advanced cryptanalytic methods for Bush to select

from. Perhaps unknown to Bush or Wenger, the United States Army\'s

cryptanalyst, William F. Friedman, was toying with ideas about the use

of optical scanning. In April 1937, just as Bush was filling in the

design of his machine, Friedman filed a patent for a system. The

application did not mention cryptanalysis, and its examples of possible

use were related to analog business applications, such as the sorting of

packages, but Friedman must have

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realized that optical scanning had great potential for cryptology. 18

Despite such projects, Bush was facing the great challenge of creating

what was the world\'s first high-speed cryptanalytic machine. Balancing

all the factors, including his almost unshakable commitment to the three

technologies of film, optics, and electronic counting, Bush decided to

automate one of the most central new statistical methods, the Index of

Coincidence.

\(U) The Index

\(U) The method Bush and Wenger selected for the machine, the Index of

Coincidence, was the most ubiquitous of the new theoretically justified

statistical procedures. It was a formal and universal method that could

not be made worthless by a slight change in a cipher system. It was

based on the laws of probability. The Index was rugged and independent

because it needed only intercepted cipher text and because it could

attack any type of cipher system.19 It also had a wide range of powers.

\(U) The Index allowed an analyst to identify messages or portions of

messages that were produced by the same settings of an encryption

device. That was a first step to determining the wiring and settings of

the encrypting components of the machines. The Index of Coincidence

could then be put to work to identify a cipher key or the order of the

cipher wheels in a machine. Such new methods were essential to an

independent attack on the cipher devices. The stepping switch and

wired-wheel machines, such as the Japanese Purple and the German Enigma,

were designed to be unbeatable. They had cascades of transposing rotors

which repeatedly changed one letter to another. Although each rotor was

simple, together they produced a long sequence of letter substitutions

without repetition or pattern.

\(U) Such machines as Red, Purple, and the Enigma came close to creating

a random sequence, but not quite. They appeared to be ran

dom because of the length of the cycle of unique substitutions created

by the three or four rotating enciphering wheels or switches. But after

26 x 26 x26 or more rotations, the wheels returned to their initial

positions, and the machine began to repeat its letter substitutions.

That made them technically nonrandom and allowed many nations to use

Index methods against the simple Enigmas ofthe Spanish Civil War. 20

However, every nation was improving its cipher machines. Additional

wheels with unique transpositions, varied latches that turned a

neighboring wheel erratically, and plugboards to further disguise a

machine\'s input-output relationships were added to many devices. The

combinations of wheels, wheel settings, and plugboard links meant that

trillions of possibilities had to be explored.

\(U) In response, cryptanalysts countered with various forms of

automation. But most, like Poland, bet on limited methods and machines,

ones to exploit the quirks of particular cipher machines or the

procedural errors ofthe enemy. There was good reason for such a turn

away from science. The German specialists in charge ofthe Enigma, who

were aware ofthe laws of probability and also ofthe speed of film and

optical machines, were confident that it would take any formal attack

too long to be of use to an enemy. Given the special defenses built into

the Enigma, they calculated that it would take any machine so long to

perform a statistical analysis that by the time a setting was

identified, its messages would be of no military value. 21

\(U) When Wenger met with Vannevar Bush in 1937 to decide exactly what

type of machine to design, his goal was the creation of a device so

rapid that pure statistical analysis would be practical. After balancing

the needs of OP-20-G and the technological possibilities, he and Bush

decided to automate the heart ofthe IC method, coincidence counting.

\(U) A coincidence was the appearance ofthe same letter in the same

relative position in two or

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more messages or in an offset of two copies of the same message. The

method could be extended to the identification and counting of more than

single letter matches, but the essence of the Index was the counting of

single coincidences. If the number of matches exceeded the number

expected from a random distribution of letters, then both messages were

probably a product of the same wheels, wheel settings, and portion of

the encryption machine\'s cycle.

\(U) As the enciphering machines became more complex, the Index developed

an almost insatiable demand for data. The Index could be computed with

electromechanical machines, such as a counting sorter or a tabulator

with additional relay circuits. But even with the IBM machines, the

process was very slow and labor intensive; a long message could take

days to analyze. One of the reasons the Index was selected as the method

for Bush to automate was that it was so difficult to perform on

electromechanical equipment.

\(U) An Added Bonus, Possibly

(S//SI//REL) Wenger and Bush were committed to mechanizing the IC

method, and both wanted to encourage the navy\'s codebreakers to apply

mathematics, but Wenger realized that the operating codebreakers had to

use some less than \"scientific\" approaches. If Bush could automate

them, the MIT machine and statistical methods might receive a friendly

evaluation by the crew at OP-20-G. Bush agreed to sketch machines for

those rather crude methods, and he hinted that he would try to have the

proposed Comparator (for the IC) be able to perform two of them. Both

methods, the Brute-force search and Symmetrical-sequences, asked for a

search through massive amounts of data to \"locate,\" not count,

coincidences. The coincidences sought were not based on individual

letters, but matches between relatively long strings of cipher text or

long strings of text whose letters had been transposed into their

position relative to the starting

letter of the string. Both approaches were ways to identify messages

that were likely to have been produced by the same key. They were used

to find messages that were in \"depth.\" No mathematics was required; a

machine just had to sense the long coincidence and then inform its

operator where it was located.

\(U) Bush Outlines the Machine and Sets Difficult Goals

\(U) After the navy contract was signed in January 1937, Bush took time

away from his other duties to work on the architecture of his Index

machine, the Comparator. He decided to divide the project into four

major parts corresponding to functional units of the proposed machine.

Then, he chose what hardware was to be used in each. Last came an

equally challenging step, finding the four men he needed to fill out his

sketches and, perhaps, build a machine.

\(U) Bush had a frustrating time finding qualified men. The need for

secrecy made it almost impossible to locate men and still maintain good

relations with the faculty. Only three people at MIT, really two, knew

what the work was for. Bush and the project manager knew details, but

MITs president learned only that secret work was in progress. The men

who were to build the components and their regular faculty supervisors

were not told of the navy connection. Once employed, they were

instructed to be confidential about their work but not told why. They

would never be informed as to what their components were for. 22

\(U) Two graduate students received the initial assignments. Jerry

Jaeger, who had abackground in machine tools and automatic controls, was

given the first task, to build the critical input mechanism. Richard

Taylor, who was already important to the Rockefeller project\'s

electronics and who would soon take charge of the Center of Analysis,

was chosen to be responsible for the electronic circuits. The third man,

who was asked

to develop the component to read the data tapes, was in a somewhat

different position at the Institute than Jaeger or Taylor. Herbert E.

Grier was a graduate of 1933 who remained at the Institute as an unpaid

research associate. Bush was unable to find the needed fourth man among

the student body. He turned to one of the Institute\'s machinists,

Walter Kershner, to design and construct what seemed to be the least

challenging part of the Comparator, its data input device. Kershner

probably had been working on a similar automatic tape punch for the

Rockefeller Analyser.

\(U) Finding a manager for the project was a greater challenge. It was

not until early summer 1937 that Bush thought he had a lead on a

qualified engineer: Waldron Shapleigh MacDonald.

\(U) MacDonald was one of the most unusual and fascinating ofMITs

students, and he remains an unrecognized figure in the birth of the

modern computer. MacDonald first appeared at MIT in the early 1930s when

he enrolled as a special undergraduate student. His initial year in

Cambridge was spent trying to prove to the electrical engineering

faculty that his lack of formal preparation was not a barrier to

academic success. Although he performed well in his classes, he was

unable to surmount bureaucratic hurdles, illness, and the depletion of

his savings. He had to leave MIT without a degree. But he quickly found

very well-paying work as an engineer and began a lifelong career as an

innovator in computers and automatic controls.

\(U) Bush offered MacDonald a professional salary and help in obtaining a

master\'s degree in electrical communications at the Institute. In

return, MacDonald was asked for a firm commitment to come to MIT to see

the navy\'s project through to completion. But MacDonald needed time to

fulfill his existing responsibilities, and he did not arrive at MIT

until September 1937, leaving only some ten months to become oriented,

to check and revise the Comparator\'s parts, prepare

reports, and assemble and test the historic machine. 23

\(U) MacDonald\'s ingenuity and his hands-on engineering ability were

needed on the navy\'s 1930s project, but his role was not a truly

creative one. Well before he arrived in late 1937, the design of the

machine and the schedule for the project had been determined. His job

was to make what Bush had specified come to life and to do it before the

end of the navy contract. Unfortunately for MacDonald, he inherited a

fixed design, components which were hastily made by others, Bush\'s

order to \"get the job done on time,\" and full responsibility. By

September 1937 Bush was already too busy with his other work to attend

to the now rather inconsequential navy project. Among other things, Bush

was readying himself to assume the leadership of the powerful Carnegie

Institution.

\(U) The Comparator Really Doesn\'t Go to Washington

(U//FQUQ) Bush and Wenger were very wise insetting the limited goal of a

machine for the Index of Coincidence. Electronic computation was having

its birth pangs, and no one had a way to create a machine whose hardware

could be made to imitate any process. A major reason why all the 1930s

computers were limited in function was the absence of a viable memory

technology.24 A universal data computer, one that worked on large

volumes of input and that had high-speed memory, did not appear until

the 1950s. Then, machines such as the UNIVAC depended upon very

demanding, slow, and expensive, magnetic tape memory systems

25

(U//FQUO) Bush\'s first sketches of his Comparator reflected the

limitations of the memory and electronic technologies. Each of the

Comparator\'s four major components had its own very significant

practical challenges. The state of the technology did not allow elegant

solutions to the problems of high-speed input, sensing, count

ing, and recording. Because of the conduct of the 1930\'s Comparator

project and the nature of OP20-G\'s early wartime efforts, it was not

until late 1943 that America had more than the patched-up Bush

Comparator to represent its nearly fifteen years of attempts to build

sophisticated electronic codebreaking devices.

\(U) Too Much to Ask of Mere Machines

(T0//01//REL) The Index was a demanding cryptanalytic method. To tally

all the possible single letter coincidences in two messages calls for

(n\*(n-i)) comparisons.26 If two four-letter messages are examined for

coincidences, twelve comparisons must be made; 500 messages demanded

almost 250,000 tests; a 2,000-letter message called for almost

4,000,000. Complete analyses of long messages could take days or weeks

by hand and tabulator methods. Compounding the challenge of raw speed

was Wenger\'s demand that the Comparator be able to handle the longest

messages. There was good reason for that because the more characters in

a message the more likely that something of value would emerge from an

analysis. Fortunately, cryptologists around the world knew that messages

with too many words posed a danger to their systems and instructed that

messages be limited to as few words possible. The very upper limit was

2,000 characters. Messages of 200 characters were typical, but the need

to analyze longer ones in a timely way made speed and a large memory

important goals. 27

\(U) Combined with Bush\'s desire for a minimal number of electronic

components, the call for speed created unexpected challenges for the

students at MIT. One of them was printing. To maintain speed, printing

had to be done while the tape was running. The solution Bush and his men

devised was sensible but crude, and it led to a need for an even faster

mechanical tape drive. Printing was to take place while a blank portion

of tape was running. Tn practice, this meant that approximately one half

of each tape was blank,

thus halving the number of possible comparisons during a am of the tape.

Because of that, Bush\'s men had to double the originally planned speed

of the drive to achieve the processing goals. 28

\(U) Even without the tape handicap, Bush had to outdo much existing

technology to achieve his minimum Comparator speed.29 Bush wanted the

machine to deliver data to the reading station at over thirty times the

rate of standard telegraph equipment and sixty times faster than a movie

projector if it was to reach the goal of 20,000 comparisons a minute.

Even in the late 1940s, the most sophisticated high-speed transmission

\"baud rates\" were in the range of 1,800 characters a minute - or more

than ten times slower than Bush needed in order to make the navy machine

an attractive alternative. There were special highspeed drives for

sending bulk messages, and during World War II \"flash\" systems were

developed. Those devices, however, were not proven in the mid-i930s. The

talking picture industry did not provide much help. In the 1930s, moving

picture film was moved at less than 300 feet per hour.30 The Comparator

had to sense and route data at rates forty times greater than an IBM

sorter and 160 times faster than a tabulator.

\(U) Wenger thought that he might overcome the bureau\'s protests if Bush

could add parallel features to his essentially serial machine. Wenger

asked him to try to include what would be needed to make isomorphic and

three- and four-letter (polymorphic) coincidence tests that had been

discussed earlier.

(T8//SI//REL) Wenger also gave his approval for the \"locating\*

feature. It would allow what the World War II cryptanalysts called

\"brute force\" searching. Masses of data could be scanned at every

position of two messages with the hope of finding indications that two

messages had been enciphered with the same key.

\(U) No Thanks for the Memories

\(U) Because the Comparator was a datadependent machine, the greatest

problem facing Bush\'s students was how to store and retrieve

information. The Comparator needed a largescale and very high-speed

memory, but such memories did not exist in the 1930s.31 What was on the

technological horizon was not encouraging. Storage in massive banks of

capacitors or resistors, which some computer designers were thinking of

using, was too expensive, and such banks took too long to load and

unload.32 The rumors about the use of special versions of television

tubes as memory were just that in the mid19305. And no one thought that

delay lines would ever be able to hold more than a few bits of

information. In 1937 work was just beginning on magnetic memories, and

storage of large amounts of data in two or multistate electronic tubes

or relays was out of the question. 33

\(U) Unfortunately for Bush and Wenger, there had been few advances in

tape technology since the introduction of modern automatic telegraph

readers in the early twentieth century. Standard teletype technology had

not evolved into a competitor to the punch card.34 In early 1937 the

only option seemed to be microfilm.

\(U) Bush thought his men would overcome the difficulties caused by film

shrinkage and distortion when the film was sped past a reading

station.35 Unfortunately, microfilm proved too difficult for a machine

that could meet the mid-1938 deadline for the delivery of the

Comparator. As a result, in mid-1937 Bush sent his students on a hurried

search for another medium and a way to move it at incredible speeds. The

MTT men chose a unique 70mm-wide paper tape that EastmanKodak used for

packaging its movie film. It was strong, wide enough to accommodate

Bush\'s coding scheme, and, very important, it blocked light because of

its acetate coating and its alternate red-black layers.36 Also, early

tests indicated the tape would maintain its structural integrity after

being punched. All those features justified the high cost of the Eastman

product although it was soon learned that its data capacity would not be

much more than that of telegraph tape. 37

\(U) The disappointingly low density meant that much effort had to be put

into the development of a high-speed tape drive, one burdened with some

very special demands. In addition to the need for ultra-high speeds, the

tape transport had to pass two tapes in perfect alignment over the

reading station, then step one tape one character relative to the other

until all possible comparisons had been run. 38

\(U) The Limits ofMecJianics

\(U) The first man on the summer crew was given the responsibility of

creating the mechanical combination needed to compensate for the low

data-carrying power of the Eastman tape. Already familiar with the

drives in the machines used in the cloth and newspaper industries, the

young engineer decided to center his component on a four-foot long frame

to hold the tapes. Pulleys were to maintain the required tension on the

loops of tape. Driven by a fast electric motor and a system of shafts

and gears, the tape was guided by both rollers and sprockets.39 The

entire transport was mounted on tall legs and stood some four feet off

the ground to ease the chore of changing tapes. 40

\(U) The tape transport was well designed and was delivered on schedule,

but it did not reach the speeds Bush desired. At its best moments it ran

at less than two and a half miles an hour, not the five or more needed

for a truly rapid machine. The tape was the machine\'s timer and set

many of the requirements for the other major components. Once its

features were known, work on the reading station and electronic counters

could be completed. Armed with Bush\'s previous instructions and the

specifications for the tape drive, the next man tackled the problems of

photoelectric sensing.

\(U) Let There Be Light, But Not Too Much

\(U) One of Bush\'s first technical commitments was to the sensing of the

presence of light rather than its absence. Following on that, he ordered

his men to code each letter of a message by punching a hole in a column

of the seventymillimeter wide tape. There was to be only one hole to a

column of twenty-six fields. An additional field in each column served

as a timer. If a column held data, this extra field was punched. When

two active columns overlapped, light was directed to a timing cell which

then readied the sensing photocells to examine many data columns

simultaneously.

(C//SI//REL) There were to be at least ten data columns, thus letters,

packed into a linear inch of tape. To accommodate Wenger\'s need for

counting more than single coincidences, ten letters were to be read at

one time. This called for ten photocells for message characters, one to

each column.

\(U) The engineer had to create a mask to ensure that light that shone

through the first tape did not drift before it fell on the lower one. He

also had to find a lens that would direct the light beams from

overlapping holes, one for each column, onto the correct sensing

photocell. An allied problem was more challenging: he had to keep light

from a coincident column from spilling over into the area of another

column\'s photocell. The state of photocell technology did not allow

easy solutions to any of the reader\'s problems. Among other problems,

they remained fairly large. As a result, the young MIT engineer could

not put ten of them directly under the columns of the Comparator\'s

tapes. They had to be placed far under the reader and were arranged in a

\"U\" pattern. That meant that the straight, parallel light from the

coincident columns had to be accurately deflected. Moreover, complete

electronic packages for the photocells were not supplied by

manufacturers. The MIT engineer had to tune each photocell and build the

amplification circuits to

turn the signals from the photocells into the discrete pulses needed by

the third major component of the Comparator, the electronic counters.

\(U) The Most Difficult Problem of All, But It Wasn\'t

\(U) With the knowledge of the tape and photocell systems, the third

young man began his work on the final details of what everyone thought

would be the most difficult part of the project, its electronic counting

system.

\(U) Precise digital counting with electronics was in its early years,

and all attempts at creating tube-based calculating circuits were risky.

Electronic tubes were designed for analog work, and it was only

empirical tweaking that allowed them to be on-off switches. As late as

1940, the best experimental electronic counters worked at 20,000 decimal

counts a second during their cooperative periods.

\(U) One of his greatest challenges was the circuitry for the

Comparator\'s parallel-processing feature. It was needed to allow the

machine to perform the simultaneous multiple letter tests that were so

valuable to the cryptanalysts. Without parallel processing, the

machine\'s power would be reduced by a factor of four. The student

engineer had to construct five independent electronic counters which

were to tap the data from the reading station at the same time. The

young man took the safe technological route, choosing to stay with the

predictable and familiar gas-filled Thyratrons.

\(U) The choice of architecture for the counters was also driven by the

need to send the navy at least a feasible design, if not a machine, by

mid1938. Like the other electronic computer builders ofthe era, the

young MIT engineer decided to imitate mechanical calculating machines. 41

His counters were decimal, not binary. Although such a design limited

the range ofthe application of a computer, it was known to work and was

simpler

to construct than binary circuits. Each of the decimal counters was to

consist of three or more rings often tubes with the needed electronics

for arithmetic carrying, power, and control.

\(U) Providing the option of performing several different analyses at one

time meant additional challenges. Bush had designed the machine to allow

the analysts to select the particular tests for each run. To permit

this, the young engineer incorporated a set of \"and\" circuits that

could be set to test for the desired combination. The Comparator\'s

Rossi \"and\" circuit was the key to the machine\'s flexibility and

parallelism.

\(U) In addition to the counters and the \"and\" circuits, the third

engineer was handed another tough job. He was given the responsibility

for creating the banks of electrical relays needed to stand between the

high-speed tube counters and the much, much slower printer. At the end

of each pass, the counters had to be polled for their contents and

numbers sent to the relays. The relays worked as a short-term memory,

sending pulses to the magnets that controlled the print bars.4\"

\(U) The Easiest Becomes the Most Difficult

\(U) There was a fourth man. He was in charge of the crucial data-entry

system. The punch for the data tapes proved to be the Achilles heel of

the Comparator. The problem was a perhaps inescapable result of the use

of paper tape, as was Bush\'s inefficient 1 of 26 coding scheme.

\(U) The technology of the 1930s led him to reject a method of coding

that could have increased densities on the tapes by at least a factor of

five and that would have led the Comparator\'s codes to fit with the

navy\'s modern communication system. The use of a five-field character

code, the Baudot code, would have allowed at least five letters to be

placed on a line (column) of the 70mm tape. But the size and sensitivity

of holes and photocells, the problems of aligning tapes, and the desire

to limit the elec

tronics of the machine precluded the use of that coding pattern. 43

Bush\'s special coding scheme demanded a custom-made and very complex

mechanism.

\(U) An MIT machinist was instructed to make a keyboard-operated device

to simultaneously punch two exact copies of a message. It had to keep

the two tapes in perfect synchronization and to make precisely spaced

tiny holes in each column and row. The punch had to advance the tapes

with absolute precision. Most challenging, it had to maintain the

integrity of its tiny and sharp needle-like punching arms despite the

impact as the arms struck the Eastman tape. The machinist was asked to

devise tape cutters and the means to ensure that the spliced ends of the

tapes would not pull apart during the runs. Unfortunately, the punch was

the last component of the Comparator to be turned over to the project

manager and then it was \"not satisfactory.\" \*\* The punch\'s

inadequacies cannot be blamed on the machinist; the responsibility has

to be placed on the original design for the Comparator. Between 1938 and

1945 several teams of engineers tried to produce a viable data entry

system for the paper tapes; none was able to build a rugged and reliable

punch.

\(U) Beyond Murphy\'s Law

\(U) When Waldron MacDonald arrived in September, three student engineers

had already sent their work to local machine shops. Bush trusted their

judgment so much that, without examining the parts, he put MacDonald to

writing the descriptive reports for the navy. MacDonald took Bush\'s

first schemes for each component, added what the students had done, and

sent the reports to the navy for payment.45 The reports, including the

final one submitted in the spring of 1938, were upbeat and gave the

specifications for what everyone thought would be the first operating

electronic data processing machine,46

\(U) Although the reports contained a bright picture, the Comparator

project had fallen victim to a host of problems. But the main reason for

the problems in 1937 and 1938 was the technologies Bush so admired. They

were not ready to be turned into useful machinery. Unfortunately, the

results Bush and his young men expected on the basis of their early

bench tests did not carry through to the parts they gave to MacDonald.

The Comparator was far from ready for assembly. And only MacDonald was

left to rescue it! MacDonald had much, much more to do than simply link

the components together. Almost every component had to be reworked.

\(U) MacDonald put much thought and energy into reshaping the electronic

components, and he more than fine-tuned the tape transport. More basic

work had to be done on the reader. The optical system needed a complete

overhaul, and it took much of MacDonald\'s attention. To bring the

correct amount of light to each of the ten cells, he devised a 1930\'s

version of fiber-optics.

\(U) Thus, MacDonald\'s assignment turned into something much more

demanding than either he or Bush had imagined in mid-1937. MacDonald was

not sure that he could solve all the problems of the transport,

counters, and optical sensors. Then chance compounded an already

difficult situation. In a friendly game of touch football, MacDonald was

knocked out by an unlucky \"poke on the jaw.\" MacDonald remained

unconscious and confined to bed for several weeks. His energy was

seriously drained for months afterwards.47 Despite the injury, Bush

chose not to replace MacDonald.

\(U) What Hooper had complained about for so many years, the lack of

appreciation of science in the navy, again struck the Comparator.

Wenger, the strongest voice for a revolution in the technologies of

signals intelligence and cryptanalysis, readied himself to leave for sea

duty in mid-1938. Wenger had to spend the five months before he was

rotated putting the finishing touch

es on the detailed reports for Hooper\'s grand proposal for a modern

communications system. Wenger left the country just a month before

MacDonald shipped the troubled Comparator to Washington.

\(U) In spring 1938, MacDonald began test runs on the rebuilt parts.48 He

also had the chore of instructing the engineer the navy sent to learn

about the machine. Wenger had arranged for a bureau technician to spend

some time at MIT. During the spring, Frederick Dulong, one of the many

ex-navy men who stayed on in Washington as civilian employees, was sent

to MIT.

\(U) Wenger considered Bush very generous for having constructed a

machine and approved Bush\'s suggestion that MacDonald be hired by the

navy to fine tune the Comparator once it was in Washington. The bureau

agreed and requested MacDonald to travel to Washington with the

Comparator and to stay for three months. He was to adjust the machine

and to instruct both technicians and cryptanalysts in its use. Safford,

now in charge of the Comparator, was pleased that the bureau promised to

give him some additional, if not permanent, help.

\(U) As soon as Bush signaled that a machine would be sent to Washington,

Wenger began expensive preparations. He requested the money for tapes

and lights and extra tubes, and he readied an area for the Comparator

within OP-20-G\'s secret rooms. In a few weeks, additional funds were

requested for the hardware necessary to prepare the tapes for the

Comparator.49 Wenger went much further. Describing a new era in

cryptanalysis, he convinced the navy brass to give serious consideration

to funding more devices.50 By the end of 1938, OP-20-G\'s budget request

included more than \$20,000 for additional Bush devices and special

additions to the first machine.51 In addition, \"G\'s\" new war plans

contained a request for a Comparator for the pro

posed major cryptanalytic station at Pearl Harbor. 52

\(U) Spring Is a Time for Love, Not Machinery

\(U) When the Comparator arrived in Washington in late June, a month

late, it would not start,53 As bad, two of its most important parts had

not been shipped -the punch and printer. About a month behind schedule

and still only \"semifinished,\" it found anew and wellintentioned

guardian. But Fred Dulong could not give full attention to the machine.

By mid-July, Dulong was able to run the counting circuits,54 but any

more work was stalled because of the missing punch and printer. Unknown

to anyone, they had been placed in a Cambridge safe-deposit box

byMacDonald to await his return to the country in August55 following a

honeymoon.

\(U) The cryptanalysts certainly did not have the time to wet-nurse the

Comparator. While the bureau\'s men bewailed the results of becoming

entangled with an impractical professor, the cryptanalysts in charge of

the day-to-day work were coming under incredible pressures to penetrate

all of the sophisticated Japanese code and cipher systems. Japan\'s

invasion of China in 1937 had made it clear that war was imminent,56 and

by 1938 OP-20-G was facing crisis conditions. The sinking of the Panay

in December led to a scramble to protect American codes. In addition,

there were hints that Japan was about to make another sweeping change in

its codes and to introduce its Purple cipher machine.57 What energies

OP-20-G had were necessarily devoted to developing techniques and

machines that gave immediate results. Its faith was, quite naturally,

placed in the direct analogs of Japan\'s enciphering machines, and its

men wanted resources devoted to modernizing the tabulators.

(TJ) Thus Waldron MacDonald did not arrive in Washington at the right

time for any experimentation at\"G\" or the bureau. Driving from

Cambridge in August 1938, he had the Comparator\'s punch and printer in

the back of his station wagon. Working in OP-20-G\'s downtown offices,

MacDonald attempted to save his and Bush\'s reputation.

(ID He hurried the Navy Yard\'s effort to build tape duplicators and

splicers and soon convinced the bureau to build a new punch. The one

from MIT could not be coaxed into working. Don Seller took on that

challenge.58 Then MacDonald began working on the other components.

Although no major changes were made to the Comparator, it took an

unexpected fourth month of work to announce a finished machine in

November.

\(U) In late 1938, OP-20-G\'s leader, Safford, congratulated Bush and

informed him the cryptanalysts and the bureau\'s men planned to spend

the next year experimenting with the wonderful and reliable machine.

Possibly because they now realized how much a well-schooled optical

electronics engineer would cost, OP-20-G did not make an effort to hire

a replacement for the MIT engineer or, as planned earlier in the year,

to construct at least one more Comparator. 59

\(U) R.AM Project Seems to Die, Late 1938

\(U) With Wenger gone, no one pressed for an immediate extension of the

program.60 Bush, in turn, quickly fended off another attempt by the navy

to link him to \"G\'s\" projects. The consequences of the failure to

continue on with the Comparator project in 1938 were severe. Soon after

MacDonald left Washington, the Comparator again became inoperable. It

was so temperamental that the only attention it received was from

Dulong, whose many other duties allowed just part-time work.61 It was

listed on OP-20-G\'s equipment roster in 1939, but it was never used,

not even on the type of important project for which it had been

designed, the breaking of the Japanese Purple cipher machine.62 Its

technical problems become so great that it was removed from the

cryptanalysts\'

quarters and sent to the Navy Yard where it could be tinkered with.

\(U) Although overworked because of the Japanese code and cipher crises,

Safford had asked for a report on the Comparator and received some very

disheartening news. Dulong responded that nothing but the electronic

counters proved reliable, and the machine had not been functional long

enough to allow in-depth development of procedures. The Navy Yard\'s men

did not think there was any possible quick fix for the device. Most

ominous was the failure of the data entry component, the punch. Even the

second version of that purely mechanical and supposedly simple mechanism

could not be made to produce precise tapes. There was little hope of

basing an entire system of analytical machines around the original Bush

design if there was not an efficient and reliable data entry device. 63

In 1940, Safford, who two years before declared the Comparator a

reliable and useful invention, had to admit the machine never worked and

that the entire project had not progressed as planned.

\(U) A Comparator There May Never Be

\(U) In late 1940 Bush gained another chance to prove the power of

optical-electronic machines and the ability of academics to create the

technologies of defense. 6\* He arranged for MITs John Howard and his

men to rescue the first paper tape Comparator and to design the

longpromised microfilm version.

\(U) This second MIT OP-20-G project of late 1940 is of extreme

historical importance because it became the foundation for the United

States Navy\'s incredible Rapid Machines Program of World War II. That

little known adventure rivaled Britain\'s famous work on the Bombes and

the Colossus.

\(U) Tragically, that program is also important because of its failures.

Although it began with expectations of producing electronic digital

machines to attack the feared cipher devices of the Axis powers, it

turned to older technology and logic. To be able to provide anything of

value to OP-20-G, Howard\'s men had to step back from electronics,

digital techniques, and microfilm. Although the navy\'s cryptanalysts

began World War II with promises that electronics could be made to work,

they had to wait for almost two years after Pearl Harbor before any

machines appeared that affirmed that Bush\'s ideas had potential.

\(U) The story of John Howard\'s navy project has to begin with the

crises in Europe and Asia, policy decisions in the White House and

London, and the organization of American science in World War II.

\(U) Big Science Begins to Emerge

\(U) Bush\'s high-science friends were active in more than the cause of

research. They were among the nation\'s earliest supporters of a

positive response to the German threat. They lobbied for the creation of

the National Defense Research Committee (NDRC). The NDRC was the

realization of Bush\'s ideal of how to link academia and the military.

Given almost complete power by Roosevelt to shape the NDRC, Bush laid

down ground rules that gave power to academics to begin research

projects and to be free of military control. Having its own funds and

being a presidential creature, the NDRC and its more powerful extension,

the Office of Scientific Research and Development, could initiate

blue-sky programs and carry them through to development.

\(U) One ofthose programs interlaced the NDRC with American

cryptanalysis, but only after it had dealt with along list of projects

of much higher priority. Atomic power and radar were the leading

problems, and the scientists at the most prestigious universities and

corporate research centers received the first calls from the NDRC\'s

leaders.

\(U) The executives at the NDRC realized that atomic research and the

development ofthe potentials of radar called for advanced computation,

but, alone, those problems would have led to a minimal NDRC involvement

in computers. It was a lower priority challenge that plunged the NDRC

into computer research and established who would participate in the

navy\'s future Rapid Machine effort. Atomic scientists were calling for

electronic control devices, but most important for the history of

OP-20-G was the hope that radar could be used to automatically control

antiaircraft weapons. That led to the NDRC\'s involvement in the

development of electronic fire control computers in the early 1940s. 65

\(U) The exploration of such electronic digital machines was the perfect

type of work for the NDRC because it centered onunproven and

experimental technologies. The NDRC\'s scientists believed that digital

electronics had potential, and they rekindled the fire control projects.

Hundreds of thousands of dollars were poured into fire-control computer

and atomic-counter work in the first two years of NDRC\'s life.

\(U) Fire Control

\(U) The NDRC began the first stages of its fire control project in June

1940. Bush\'s old friend Warren Weaver ofthe Rockefeller Foundation

assumed command. The research at RCA, which had led to the design ofthe

fastest binary circuits in the nation, if not the world, was picked up

by the NDRC. Then Weaver coordinated the work at RCA with wide-ranging

explorations at Eastman, MIT, Bell, and, to some extent, NCR Of

significance for the history of OP-20-G\'s machines, IBM was again left

out ofthe NDRC circle although its centers of electronic research were

working on quite advanced components and systems. 66

\(U) Because ofthe NDRC\'s stimulus, by the time of America\'s formal

entry into the war, RCA Eastman, Bell, and MIT had several proposals for

digital-based fire control systems, ones the NDRC

evaluators thought had great promise. In the spring of 1942, meetings

were called, and all participants shared their knowledge and designs. 67

The reports ofthe fire control projects were made available to the

American technical community, which now included John Howard. He was

made aware ofthe designs for the most advanced computer components.

\(U) Many ofthe fire control developments would find their way into

cryptanalytic machines and into such pathbreaking computers as the

ENIAC. By mid-1942, there were great hopes for the development of at

least a prototype electronic gun controller. But Warren Weaver and his

assistants concluded that digital electronics was too good. It was too

fast and too precise for the guns used by the military. In July 1942 the

fire control program was dropped - but with three important exceptions.

The development projects for the Eastman film-based analog-to-digital

signal converter and RCA\'s fabulous multifunction Computron tube were

to be continued, as was NCR\'s counting circuit research. Although they

were viewed as long-term projects, the three efforts were financed for

only a few more months because the press of other work forced the NDRC

to abandon them. 68

\(U) The Second Comparator

\(U) Meanwhile, just weeks after the work on high-speed electronic

counters and fire control computers had begun, Bush and OP-20-G came

together. A visit with Bush in early summer 1940 indicated a reawakening

of interest in the original Comparator, which had sat unused at the Navy

Yard for almost two years. But it was not until October 1940 that

anything was done about its future.

\(U) A limited and secondary role for MIT was unacceptable to Bush,

however. He returned to his old demand for freedom from bureaucratic

control, and, within a few weeks, he was able to reshape the first