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The History of Compucorp

By Rick Bensene
Major Revision 10/31/2003

Updated 11/12/2017


Calculators made by Compucorp are extremely interesting and wonderful calculating machines. Compucorp machines had a real style about them, both in terms of their physical appearance, and their high-end functionality. Technologically, Compucorp's calculators (and those sold by OEM customers including Monroe(US), Smith-Corona/Marchant [SCM] (US), Deitzgen(US), Sumlock(UK), IME(Italy), Seiko(Japan) and Ricoh(Japan)). were highly advanced, pushing the state of the art in large-scale integrated circuit technology, as well as utilizing a very computer-like architecture. Compucorp's unique architecture used a multi-chip general purpose CPU (the precursor to a microprocessor) with specialized ROM-based software making up the personality of each different model of calculator. The flexibility of the architecture allowed Compucorp to manufacture a wide range of calculators for many different types of applications, including scientific, statistical, financial, and even for surveying work. Compucorp's later calculators blurred the line between calculator and computer, offering highly-expandable calculator processors that could be connected to a diverse range of peripheral devices to form what, for all intents and purposes, was a small computer system.


The WS-01 was quite an amazing machine for its time, utilizing a rotating magnetic disk (remotely related to the hard-disk drives found in a PC today) with six dedicated tracks (with each track having its own read/write head) for storage of the working registers of the machine. A dedicated seventh track contained a pre-recorded timing track that served as the master clock for the logic of the calculator. The logic of the WS-01 was formed using discrete transistors and diodes. The machine used a CRT display that provided on-screen display of the six calculator registers, each with a capacity of 24 digits. Unforuntately, there were reliability problems with the magnetic disk storage device, and a redesign was done to replace the unreliable disk with a form of solid state storage. By late 1964, the "Wyle Scientific" Model WS-02 was introduced. The primary design change between the WS-01 and the WS-02 was replacement of the magnetic disk memory with a magnetostrictive delay line for the working register storage.

The WS-02 was virtually identical physically to the WS-01, and had exactly the same feature set. Electronically, the main difference was changes to the logic to accomodate the delay line memory versus the disk memory system, as well as to generate a master clock for the calculator.

For both the WS-01 and the WS-02 Scientific calculators, the display showed the content of the three memory registers, along with the entry register, the accumulator, and a multiplier/quotient register. The machines provided the standard four arithmetic functions, plus single-entry squaring and square root. Both machines were designed to allow add-on peripheral devices such as printers, external displays, a punched card reader, and paper-tape reader/punch equipment. When equipped with the optional external punched card reader, the machines were programmable via standard IBM-style pre-scored punched cards that could be taped together to form loops which allowed repetitive operations to be performed automatically. The card reader could read both forward and backward, allowing true branching and looping operations to be performed.


The Wyle Laboratories WS-02 Calculator
Image Courtesy of Randy Liebermann


The inability to convince management that a new calculator project was needed to replace the dataed WS-01/WS-02 machines didn't mark the end of electronic calculators at Wyle Labs, though. Sometime in late 1965, Wyle Labs was contacted by Nippon Calculating Machine Co. (NCM), of Tokyo Japan. NCM had been very successful in the Japanese mechanical calculating machine market, and in July of '66, entered the electronic calculator marketplace with the introduction of its own desktop electronic calculator, the NCM Busicom 161. This calculator utilized transistorized circuitry and a small (256 bit) magnetic core memory for working register storage. Intrestingly, the Busicom 161 shares a great deal of basic design methodology with the early calculators made by Industria Macchine Elettroniche (IME) of Italy. There were accusations by IME that the Busicom 161 was a cheaped-down copy of its elegant and extremely well-built IME 24, but nothing ever really came of it. Whether or not this was the case, the story appears to be lost in time. The reality was that the Busicom 161 was significantly less-expensive than other electronic calculators of the time, and was very successful. However, NCM knew that it couldn't rest on its laurels, as the electronic calculator market was expanding rapidly. There was a realization that the market lifetime the 161, and a lower-cost introduction with less capacity, the 141, was somewhat limited. NCM's management wanted a more advanced electronic calculator, and relized that it may not have all the expertise it needed to develop a more advanced machine. A search was begun by NCM to seek someone that could design and develop an advanced calculator for them.

The Wyle Laboratories AP-01 Arithmetic Processor

Wyle Laboratories had embarked on making more of a market for itself by selling OEM products based on the Wyle WS-01 and WS-02 calculators. The design of these machines was quite modular, and so Wyle offered components of the calculators to OEM customers. For example, the "calculating engine" of the WS-02 was offered as a standalone unit called the AP-01. This system could accept commands as if entered from a keyboard, and also had a coded output representation that could be used to get results of calculations. All an OEM customer had to do was add power, and interfaces to external equipment, and they had the computing capability that could be applied to any number of different applications including process control, data acquisition, and many others. It was this aspect of Wyle Labs business that attracted the attention of NCM.

The prospect of doing calculator development for other companies was something that Frank Wyle and the management team at Wyle Labs could get behind. Such development work would keep the Wyle Labs calculator engineers employed and busy, yet didn't involve all of the overhead of maintaining a calculator sales, support, and service business. There were thoughts that perhaps this role could be extended to other calculator companies, potentially bringing in some well-needed cash, while reducing overhead. Busicom representatives met with Wyle Labs, and soon an agreement was forged by which Wyle Labs would develop a next-generation calculator for Busicom, which Busicom would manufacture, market, and support as its own advanced calculator.

There was great relief among Wyle Labs products division employees when this deal was announced, and though there were some reductions in staff, this development did allow many of the core engineering team to remain employed. Work on the project began immediately. Wyle's engineers dusted off some of the concepts from the canceled follow-on to the WS-02, along with making use of new integrated circuit technology to create the design of the for NCM. The calculator design utilized a magnetostrictive delay line similar to that used in the WS-02. The use of new DTL (Diode-Transistor Logic) small-scale integrated circuits meant that the calculator was smaller and faster, as well as more-reliable than the earlier transistorized machines. This calculator design was licensed to NCM/Busicom for manufacture and sale by exclusively by NCM. The calculator was a five-function machine, with square root and two memory registers, utilizing a CRT display with vector-generated segmented digits (versus the beautiful sine/cosine generated digits of the WS-01/WS-02 calculators). The machine was introduced by NCM in November of 1967 as the Busicom 202, and sold solely through NCM's network of distributors.

While the Busicom calculator project kept Wyle Labs involved in calculator technology, during the development of the project for NCM, Wyle management kept steady pressure to move away from the calculator and in-house developed data processing equipment business, deciding instead to focus its Products Division on computer-based data collection and instrumentation systems, utilizing various commercially-marketed mini-computers versus its internally-developed data processing devices. Even though the numbers brought in by the calculator part of the Products Division were better, they still were not good enough, and it soon became clear that the days of calculator development work at Wyle Labs were running out.

Busicom 207 Calculator

The 202 was a good start on the advanced calculator that NCM wanted. However, Busicom wanted to advance its line of calculators with ever-more sophisticated machines. Wyle Labs was signed up in mid-'67 to develop machines with additional capabilities. The resulting machines were outgrowths of the technology used in the 202, and became the Busicom 207 and 2017 calculators. These machines provided additional memory registers for use in more complex calculations. The Busicom 207 came with with seven memory registers, and the Busicom 2017 with seventeen memory registers, both introduced in February of 1969. The 207 and 2017 calculators used a CRT display similar to that of the 202, and were similarly programmable via a built-in punched card reader.

The Busicom 2017 Calculator

As the calculator development projects for NCM wound down in mid-1968, Wyle Labs management decided to abandon any further business involvement in the calculator field. At the time, the last of the NCM project was transitioning out of Wyle to NCM, and it seemed a good time to make a clean break from the calculator business. NCM/Busicom was notified that there would be no more calculator development work done for them, or anyone else, and the agreement between the two companies was nullified. As it turned out, it wasn't such a big deal for Busicom, because it was already working on forging a relationship with a fledgeling Large Scale Integration IC manufacturer in the US.

This final decision by Wyle management to get out of the calculator business completely was of deep concern to a group of employees involved in Wyle's calculator business, who felt that the calculator market still held the potential for a successful business. By mid-'68, this group of folks decided they wished to venture out on their own to form a company that could focus on the electronic calculator marketplace. Among these people were Mr. Elmer Easton, who was the prime instigator of the move to form a new company, as well having some financial resources that could potentially get the new business rolling. Easton and a core group of business-minded folks from Wyle Labs decided to put together a proposal for Wyle Labs management to spin off a new independent company to design advanced electronic calculators using the latest technology.

Mr. Carlos Tomaszewski at Wyle Labs, 1967
Image Courtesy Carlos Tomaszewski

The proposal was drafted and presented to Wyle Labs management sometime in the late summer of 1968. Frank Wyle, the owner and President of Wyle Laboratories, blessed the proposal, and Wyle Labs became a major initial investor in the new company. Mr. Easton was named the President of the company. On the engineering side, Carlos Tomaszewski also joined the effort, along with a group of other talented businessmen, engineers, technicians and support staff.










The success of the marketing of the calculators by Monroe and Deitzgen had CDC doing very well, providing funding to grow the company in rather dramatic fashion. By mid-1970, it had a quite number of customers that were successfully selling the company's advanced calculators, including Monroe, SCM, Deitzgen, and Seiko, and Sumlock.


The Monroe 1665 with the CR-1 Punched Card Reader


The Compucorp 140 Statistician Calculator


Compucorp 155 Surveyor Image Courtesy Bob Smillie


The Compucorp 250-1 Bond Trader Calculator


The Compucorp 275 "Banker" Calculator


Images Courtesy Carlos Tomaszewski


The Compucorp 344 Statistician Calculator
Image Courtesy Alex Knight

The 300-series machines provided similar functionality to the desktop 100-series machines, but in two different form factors. One was the conventional desktop format, but with a newer, more modern-looking design, and keyboard keys that were of a completely different design than the earlier calculators. The other form factor packed the functions into a much smaller, easily portable, battery-operated package. The advances in integrated circuit technology that were incorporated into the ACL chipset allowed a practical advanced battery-powered calculator to be made. Both form factors abandoned the expensive and somewhat fragile Nixie tube displays of the earlier models, replacing them with Burroughs Panaplex II planar gas-discharge seven-segment displays. The desktop machines, as opposed to the earlier models, had both a display, and the Seiko line printer.

The portable machines included a battery compartment into which either disposable D-cell batteries, or rechargeable Nickel-Cadmium cells could be installed. An external power-pack provided ability to operate on AC power, as well as serving as a charger if NiCad batteries were installed in the machine. These portable machines were hugely popular, especially with people who had to perform complex calculations "in the field", such as surveyors.

AP News Report on the new Compucorp Beta 326 "Computer"
Aired 3/19/1974
Video Courtesy YouTube and the Associated Press

The 300-series calculators were marketed both by Compucorp, as well as through Monroe, and Smith Corona/Marchant. The portable machines in the series included the Model 320, 320G, 322, 322G, 324G, 326, and 326G Scientist calculators; the Model 340, 342, and 344 Statistician machines; the Model 360 and 360/65 Bond Trader/Financial calculators; and the Model 354 Surveyor. The desktop machines included the 325 Scientist and the 327 Scientist. There are likely other models of the desktop machines that provided Statistical, Financial and possibly Surveying functions, but their existence is not entirely clear at this writing.

Some of the programmable 300-series machines provided the ability to connect a specialized cassette recorder in order to provide off-line storage for programs and data. This proved to be a real advantage when volatile RAM was used to store programs. Along with cassette tape program and data storage, there were numerous other interfaces for the 300-series calculators. Peripheral options included the Model 300 I/O Writer, the Model 310 Data Coupler Interface, and the Model 395 Teleprinter-Serial I/O Interface.

The Monroe 1860



The Compucorp 402 Business Computer System


The Compucorp 403 Data Collection System

The Model 403 Data Collection System was marketed as a multi-user data entry system to capture data entered by date entry clerks to magnetic tape for processing on mainframe computer systems. The 403 utilized a 400-series calculator as the CPU and provided connections for up to four CRT-display data entry terminals. The system came with the Model 497 1/2" magtape drive, to which data entered on the terminals would be written for transfer to the larger computer. Also included was the Model 491-2 dual floppy disc drive system. The data entry forms definitions were stored on floppy discs to make it easy to change forms for differing data entry operations.

The Compucorp 450 Computing Calculator System







Text and images Copyright ©1997-2017, Rick Bensene.