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Old Calculator Museum Advertising & Documentation Archive
Electronic Arrays' First Calculator Chip set Advertisement


Electronic Arrays S-100 Chip set Advertisement
Electronics Magazine
March, 1971

As far as is known, this advertisement is the first for Electronic Arrays' initial electronic calculator chip set, known as the S-100. The chip set was announced in July of 1970, with general availability beginning in the November time-frame. The S-100 chip set consisted of six large-scale integration (LSI) PMOS integrated circuit devices that combined to form the complete logic of a calculator that provided sixteen digits of capacity with an eight digit, leading zero-suppressed display, the four basic math functions, and fixed decimal point placement.

Electronic Arrays(EA) was founded out of a small integrated circuit design consultancy called McMullen Associates, which was named after one if its founders, Jim McMullen. McMullen left pioneering MOS integrated circuit manufacturer General Micro-electronics(GM-e) along with a few of his co-workers in 1966 to form a company that would take customers' digital logic designs and would design the large-scale MOS ICs that would implement the customer's logic on a few chips. McMullen Associates had connections with some of the big custom MOS IC manufacturers who they would contract with to manufacture the chips that had been designed for their customer. Some of the early work done was for the US military and security infrastructures, which provided a good source of income for the company to allow it to take on more projects and get them implemented faster.

It didn't take long for it to become clear the customers were looking for a "one-stop" shop for their high complexity custom integrated circuit needs, especially the government agencies, which had security concerns over the fact that the IC's had to be fabricated by a third party. McMullen Associates was going to have to build out its own advanced IC fabrication facilities. With a solid cash position, and a sound business plan, investors were sought to provide capital to make it happen. Investors were lined up, both private and venture, to provide the funding needed to build out their own fabrication facility. In 1967 McMullen Associates became Electronic Arrays, adding fabrication of large-scale MOS integrated circuits to their IC design services.

At one point after EA had developed some custom ICs, as well as coming out with some large-capacity read-only memory (ROM) chips for general sale, mostly to the computer industry, the thought came up a meeting there was likely a solid market for a chip set that would implement the functions of a basic electronic calculator. The concept was that EA could design and manufacture the chip set, and make it available for sale to anyone, be it a calculator manufacturer or an electronics hobbyist who wanted to build their own electronic calculator.

The decision was made to go ahead with the design of such a chip set. The intention was to design and manufacture a microcoded chip set that would provide the flexibility of a microcoded architecture, along with segmenting the function of the various chips in the chip set to allow replacement of the keyboard input or display output chips with different designs to provide capabilities for different keyboard layouts and output devices. The read-only memory containing the microcode could also be custom-programmed to add extra functions, to allow customers to customize the chip set for their specific needs.

The chip set mentioned in the advertisement was the result of that effort. The S-100 chip set required only the addition of a power supply, some display driver electronics, display devices (Nixie tubes or vacuum-fluorescent segmented display tubes), a keyboard, a master clock signal generator, and a cabinet for everything to go inside. EA also provided design services for customers who wanted specific functionality or features for their calculator. EA would make modifications to I/O chips and microcode to suit the the customer's specifications.

The historically significant aspect behind this advertisement is that it was pitching the very first LSI calculator chip set that was for sale to anyone at the affordable single-quantity price of $158.46 for the six chips. Granted, in 1971, $158.46 was a fairly substantial amount of money, but the chip set together with the cost of the other components needed to make a calculator was considerably less expensive than buying an equivalent electronic calculator at an office machine retailer. An example of a relatively comparable commercial electronic calculator of the time would be the Sharp QT-8D, retail priced at just under US $400.

The S-100 chip set was an "open architecture" as opposed to the other calculator chip sets that existed at the time. There were other calculator chip sets around, but they were proprietary to calculator manufacturers. The design and specifications of the chip sets developed by calculator manufacturers for their calculators were kept as trade secrets by the calculator manufacturers. Iron-clad non-disclosure agreements had to be signed off by the chip-makers who the calculator manufacturers would provide their logic designs to in order for the logic to be turned into chips. The resulting chip set were used exclusively the the calculator manufacturer's own calculators. No information about the chip sets used by the calculator manufacturers was ever to be made public, as these chips were considered by the calculator manufacturers as their competitive edge in the insanely competitive electronic calculator market of the late 1960s.

Electronic Arrays furnished detailed specifications to anyone who asked, including full pin-outs, electrical characteristics, theory of operation, and even reference designs for calculators utilizing different types of display technologies. With so much information available about the chip set, it became possible for someone with a modicum of electronics skills to use the chip set to build their own electronic calculator at a price that was significantly lower than what was available on the retail market at the time.

The introduction of the S-100 chip set became the catalyst for a "pop-up" surge of calculator manufacturers who used the EA chip sets to create low-cost calculators, attempting to capitalize on the fact, as the theory goes, for a time, they could could sell a calculator based on these chips for less than most of the large calculator manufacturers, including the big-three Japanese calculator manufacturers, Sharp, Casio, and Canon.

Electronic Arrays itself got into the act, creating a new business they called "ICM", which was an acronym for International Calculating Machines (a play on IBM?). ICM built and marketed a basic electronic calculator using its own S-100 chip set, called the ICM 816, which was the first electronic calculator on the market to use the S-100 chip set. ICM immediately offered the ICM-816 as an OEM product that other companies could purchase in quantity at wholesale prices, and then place their company logo and serial number plate on the calculator, and sell and support it as their own. Some of these companies were Caltype Corporation and Lago Calc. A number of other calculator companies utilized the EA calculator chip sets to create their own electronic calculator models, including Walther(West Germany), Rex-Rotary(Denmark), Master Calculator Co.(US), SCM(US), Addo-X(Sweden), and even Japanese electronics giant, Sony.

ICM was a bit greedy when it put the ICM-816 on the market, asking $450 retail for the calculator which was considerably more expensive than similar calculators from the well-known calculator manufacturers. Needless to say, sales were not at all stellar, and it wasn't long before Electronic Arrays realized it could do just fine selling the chips, and let others compete in the calculator marketplace. The ICM division was shuttered, and the inventory of un-sold ICM 816 calculators were sold to a liquidator that began selling them off at deeply discounted prices just to get rid of them.

A around the same time that EA was putting together its ICM calculator division, a small company called MITS located in Albuquerque, New Mexico was looking for a market that they could make a splash in, and that market was the skyrocketing electronic calculator marketplace. MITS founder, Ed Roberts, negotiated with EA for even lower per chip set cost than even volume purchasers were getting, with his edge being that MITS wouldn't only sell complete, ready-to-go calculators, but would also produce a high quality kit, where a person could assemble the calculator from parts themselves, and save significant money over the cost of purchasing an already built calculator. By the time the wheeling and dealing was all worked out, EA had made some improvements to the S-100 chip set, allowing an even lower-cost chip set to be offered. This chip set was called the S-80, which Ed Roberts managed to negotiate an extremely discounted volume purchase price to build MITS' electronic calculator.

Roberts and other folks associated with MITS had written articles for a number of different electronics hobbyist magazines in the past, and it was thought that perhaps an article about a built-it-yourself electronic calculator might be of interest to a publisher. Roberts wrote an article outlining the basics of the chip set and the general design of the calculator, and submitted it to a couple of publishers. Popular Electronics magazine responded quickly, saying they would make it a cover-story in the next edition of the magazine. After a huge rush to put together a "production-ready" calculator so photos could be included on the cover and in the article, the article, entitled "Build your Own Electronic Calculator" was published as the feature story on the November, 1971 edition of Popular Electronics. This article was an introduction article for MITS' first production electronic calculator, the MITS 816. Immediately, orders began pouring in. The demand for MITS' calculator was unexpected as well as overwhelming. MITS was not prepared for the huge inrush of orders for both kits and completed calculators. They had to very quickly get more space and hire technicians to build calculators to sell as completed machines, as well as workers to package the components of the kit versions of the calculator. It took some time to get up to speed. Despite the ramp-up teething pains, the success of the MITS 816 would lead MITS to continue in the electronic calculator marketplace, offering calculators with differing features and capabilities continuing to offer their calculators in kit and fully-assembled form. (See MITS 1440, MITS 908DM, MITS 7440, and MITS 7400 for examples of follow on calculators to the MITS 816.) The kit aspect of the business was what gave them the niche in the marketplace that kept the orders rolling in. It took Heathkit, the big gorilla in the electronics kit marketplace almost 18 months before they offered a calculator kit (The Heathkit IC-2008) that was roughly comparable to MITS' 816. By that time, MITS had introduced a few other calculators and kits with higher capacity and more features than the Heathkit product.

While history has dimmed the memory of the revolution that Electronic Arrays (which was purchased by Japanese electronics giant NEC in the Spring of 1978) kicked-off by producing this first publicly available electronic calculator chip set, its impact on our world is indelible. This chip set marked the first availability of sophisticated Large-Scale Integrated circuits in a form where they were friendly enough both technologically and economically to be used by electronics experimenters and hobbyists. At the same time, EA forced the electronic calculator industry to continually work to reduce the complexity of manufacturing an electronic calculator (by using ever-fewer chips to implement a calculator, until Mostek introduced the very first "calculator-on-a-chip", the MK5010 in early 1971), which would inevitably lead to lower prices for the consumer.

The push to continually improve integrated circuit technology for electronic calculators eventually resulted in the entire central processing unit(CPU) of a small computer being put onto a single chip, which became known as a microprocessor. We all know the impact the development of the microprocessor has had on our world. While Electronic Arrays didn't end up making the first simple CPU-on-a-chip. That distinction belongs to Intel, but that's a very different, though very related story beyond the scope of this article.

Electronic Arrays' S-100 chip set could well be said to have started the snowball rolling down the mountain that led us to where we are today.