Sharp QT-8D Electronic Calculator
The Sharp QT-8D (also known as the "Micro Compet") has the distinction of being recognized as the first electronic calculator marketed to be implemented using MOS (Metal-Oxide Semiconductor) large-scale integrated circuits. While essentially true, Sharp was actually beaten to the punch almost four years before the QT-8D was introduced in December of 1969. Victor Comptometer had introduced its Victor 3900 electronic calculator in October of 1965 that used large-scale (for the time) MOS integrated circuits for all of its calculating logic. (For the full story of the Victor 3900, see the essay). The calculating logic of the Victor 3900 used 29 IC's, where the QT-8D used only four, but, in terms of historical accuracy, the Victor 3900 really was the first to use large-scale MOS integrated circuits as the sole means of implementing the calculating logic of an electronic calculator. The Victor 3900 was not made in large quantities (somewhere between 1000 and 2000 were made), and had a relatively short market lifetime, causing its historical significance to be somewhat diminished. While the 3900 may have been first, the Sharp's development of the QT-8D was most certainly a breakthrough, paving the way for MOS/LSI to dramatically increase the capability, decrease the size, and more importantly, the cost, of electronic calculators.
The QT-8D's Dust Cover
Prior to the development of Large Scale Integrated circuits for electronic calculators (electronic calculators were the first consumer application of LSI devices), the machines relied on many small and medium-scale integrated circuits, along with fairly substantial quantities of individual discrete components such as transistors, diodes, resistors, and capacitors. For an example of Sharp's Pre-LSI calculator technology utilitizing small and medium-scale integrated circuits, see the exhibit on the Sharp Compet 16.
Size Comparison, QT-8D(Left), Compet 16(Right)
Small Scale (SSI) IC's contain the equivalent of 20 or so logic gates, making up a flip flop or two, or a selection of a few logic gates. Medium Scale (MSI) integrated circuits contain more logic, around 100 or so gates. In an MSI device, functions such as an 8-bit shift register, 4-bit data selector, or binary full-adder circuit could fit on a single chip. Later medium-scale MOS (Metal Oxide Semiconductor) devices could place an entire 64-bit shift register in a single chip. These devices paved the way for the development of Large Scale integrated circuit technology. LSI devices made it possible to cram hundreds, and later, thousands of logic gates onto a single chip of semiconductor material. This made it possible for an entire subsystem of an electronic calculator (for example, the arithmetic unit) to be integrated down to a single chip. LSI devices, while initially expensive to develop, became easier and easier to manufacture as the processes became better understood and more refined. Use of LSI integrated circuits in calculators allowed calculator manufacturers with access to LSI technology (or alliances with those that had the technology) to substantially reduce their costs to make a calculator, which in turn resulted in lower cost for the consumer.
The story of the development of the QT-8D, as well as the emerging power of Sharp as a major force in the electronics industry, is a rather long journey, however, it follows the pattern of so many other successful high-technology businesses. The force behind Sharp's dominance in the electronic calculator marketplace was driven by a gifted individual, someone with the genius, vision, discipline, and persistence to lead the company into a new realm. For Sharp, that man was Tadashi Sasaki(5/12/1915-1/31/2018).
Tadashi Sasaki was born in May of 1915. The exact place of his birth isn't known for sure. He may have been born in Taiwan, or in Japan. In any case, his homeland is considered to be Japan. As Sasaki progressed through his schooling, with the focus of his studies being Japanese literature, one of his teachers recommended to him that he should consider directing his energy into the sciences. Sasaki took this to heart, and began studying the sciences with great diligence.When he finished his primary schooling, graduating at the top of his class, he had an opportunity to go to Germany to study at prestigious Dresden University, which he quickly seized. He graduated from Dresden University in 1938 with a doctorate degree in electrical engineering, as well as the title of honorary professor of the university. After earning his doctorate, the now Dr. Sasaki returned to Japan and joined the Electrotechnical Laboratory, a part of the Japanese government's Ministry of Telecommunications. During this time he worked on various electronic technologies, including improved telephone communications systems and improvements to the design of vacuum tubes. As the flames of World War II ignited, Sasaki, under the direction of the wartime Japanese government, was assigned to work for a Japanese aircraft manufacturer, Kawnashi Kogyo (renamed Kobe Kogyo after the war). At Kawnashi Kogyo, Sasaki worked on the design of radar and anti-radar systems for Japanese warplanes. After World War II ended, and the United States had begun the process of helping to rebuild Japan, Sasaki became involved with teams of engineers from the U.S. focusing on rebuilding the telecommunications infrastructure in Japan. As a result of this work, Sasaki was able to travel to the U.S. to study telecommunications technology at technology centers such as Western Electric, RCA, and Bell Labs. In 1947, at Bell Labs, Dr. Sasaki had occasion to come into contact with Dr. John Bardeen, one of the co-inventors of the transistor. In late 1947, immediately after Bardeen told Sasaki about the development of the transistor, Sasaki went back to Japan to try to spearhead development of semiconductor technology there. Sasaki had the vision to realize that transistors were going to be very big. He wanted his homeland to be able to reap the monetary and technological benefits that development of semiconductor electronics would bring. Upon his return to Japan, he went back to work for Kobe Kogyo. He worked at continuing to improve and miniaturize vacuum tube devices, and later began work on semiconductor technology. His valuable contributions to Kobe Kogyo continued through the 1950's and into the early 1960's. During this time, Sasaki was very active in promoting semiconductor technology to the Japanese government, to encourage Japanese academia to begin training budding engineers in semiconductor technology, as well as working with business to foster a commercial interest in transistors. Through his efforts, a strong momentum built behind research, development, and business exploitation of semiconductor technology in Japan.
The Sumlock Comptometer Anita C/VIIIIn 1962, something happened that captured Dr. Sasaki's attention in a big way. Dr. Sasaki heard of the development, (by the English company Sumlock Comptometer) of the first desktop all-electronic calculator, called ANITA. (See the exhibit on the Anita C/VIII). With good success selling their machine into their own market, Sumlock began exporting their amazing new desktop electronic calculator outside the UK, with Japan viewed as a prime market. The early ANITA calculators were based on cold-cathode tube technology, using devices called Thyratrons and Dekatrons. Sasaki knew the limitations of tube technology as applied to calculating machines, and figured that transistors would be the key to making a calculator that was much smaller, lighter, more capable, and easier to use. Sasaki had a vision of a complete calculator being small enough for a person to carry with them all the time, perhaps in a shirt-pocket. Little did Sasaki know at the time how quickly his vision would come to pass. By late 1963, Sumlock's ANITA calculators were selling like hotcakes all over Europe. At the same time, Fujitsu, a giant Japanese manufacturing conglomerate, acquired the company that Sasaki was working for, Kobe Kogyo. At the time of the acquisition, Dr. Sasaki had advanced through the management ranks of the company and was a now a member of the board of directors. He didn't relish the idea of becoming just another cog in the wheel of giant Fujitsu. This prompted him to leave Kobe Kogyo, taking a job at Hayakawa Electric (which later became known as Sharp Corp.). Sasaki already had contacts at Hayakawa Electric, because they had been a consumer of electronic components manufactured by Kobe Kogyo. Dr. Sasaki knew that Hayakawa Electric (hereafter referred to as Sharp) was very interested in the potential of electronic calculators, but did not have a great deal of expertise in the means to break into the business. Sharp executives knew of Sasaki's expertise with semiconductor technology. Sharp's hiring of Dr. Sasaki was a classic win/win scenario. None of Sharp's executives could have guessed just how much of an effect on the company the hiring of Dr. Sasaki would have.
The Sharp Compet 10, Sharp's First Electronic CalculatorImmediately after starting at Sharp, Sasaki was involved in completing the design of Sharp's first electronic calculator, the CS-10A (also known as the Compet 10), which was announced in March of 1964. The Compet 10 was a fully-transistorized machine, but used Germanium-based transistors. Germanium transistors were prone to reliability problems, difficult to manufacture, and were also quite expensive. Sasaki knew that silicon transistors would solve a lot of the problems inherent with the Germanium transistors of the Compet 10, and began a project to develop a calculator based on Silicon transistors. At the same time, he incorporated improvements to make the machine easier to use. The result of this project was the Sharp Compet 20, announced in September, 1965. The Compet 20 was smaller, lighter, much more reliable, and significantly easier to use than the Compet 10. These traits made the Compet 20, and a few follow-on machines, the Compet 21, 30 and 15, great commercial successes. This success provided a firm foundation for Sharp to build the very strong electronic calculator business that still prospers to this day.
The Sharp Compet 20Like any visionary, Dr. Sasaki was always looking forward. While the Compet 20 was a wonderful success, Sasaki was not content to rest on his laurels. He had been keeping a close eye on the development of a new type of semiconductor technology in the United States. The technology involved the integration of many semiconductor devices onto a single chip of silicon. Like he did with the transistor, Sasaki knew that the Integrated Circuit, or "IC", as it had come to be known, would make it possible for calculators to grow more capable, as well as shrink dramatically in size. At around the time that the Compet 20 was introduced, Victor Comptomenter stunned the world with the introduction of the Victor 3900. This machine was a wake-up call to the world that Large Scale MOS ICs were going to revolutionize the electronics industry. Dr. Sasaki realized that if Sharp didn't have this technology, the company would not be able to retain its leadership position in the electronic calculator industry. The technology used to make the ICs in the Victor 3900 had its genesis at Fairchild Camera and Instrument in the US. The actual IC's in the 3900 were made by a spinoff from Fairchild called General Micro-Electronics (GM-e), but the folks that founded GM-e had done a lot of the research into the development of large scale MOS devices at Fairchild, and had published some research papers describing how to make MOS chips with large numbers of transistors on them. Dr. Sasaki made a tireless effort to learn as much about the development of LSI MOS technology in the US by making a number of trips there and talking with the best engineers in the field. In early 1966, Sasaki had amassed the information he needed, and put his best engineers to the task of developing large-scale MOS devices within Sharp. In late 1966, world was leaking out that Texas Instruments had developed a prototype of a four-function, battery-powered handheld printing calculator called Cal-Tech that used only four Large-Scale ICs. These developments of advanced IC technology in the US further drove Sasaki to push his engineers to the edge to develop Sharp's own advanced MOS IC technology. Over the next year and a half, Sharp's engineers toiled at developing their own PMOS (P-Channel Metal Oxide Semiconductor) IC technology, and had built some prototype chips that had pretty respectable levels of integration. It was during this time of frenzied development that Dr. Sasaki earned a pet nickname within Sharp -- Mr. Rocket, which referred to his jet-set lifestyle of hopping around the globe to learn the latest developments in technology that could help Sharp lead the world in the development of electronic consumer goods, the chief of which at the time was the electronic calculator.
The Texas Instruments Cal-Tech Prototype Calculator, a source for inspiration for Dr. Sasaki
Image Courtesy Texas Instruments, Used with Permission
The Built-in Carrying Handle, and Model/Serial TagThe introduction of the QT-8D created major turmoil in the calculator business. The competitor's calculators were large, heavy, power-hungry, and cost between $500 and $1300. The QT-8D was small, easily portable (it would fit comfortably inside a briefcase), used only seven Watts of power, and came with a built-in carrying handle that made it easy to carry. Sharp and Rockwell were raking in the profits, while other calculator manufacturers had to scramble to cut prices (and thus margins) on their existing calculators, as well as having to make large investments to forge their own alliances with LSI chip manufacturers. The QT-8D marked the beginning of a shakeout in the calculator industry, with many players, including the likes of Busicom, ending up getting out of the calculator business, or out of business altogether. The QT-8D wasn't particularly fancy in terms of its capability. It is a basic eight digit, four function, AC-powered portable desktop calculator with automatic floating decimal. It has no memory capabilities or additional math functions. However, that didn't really matter in the market that the machine was designed to sell into. The QT-8D was targeted at business, where the need for small, easy-to-use machines that could add, subtract, multiply, and divide was very strong. The QT-8D was even marketed (see an early Advertisement for the QT-8D and it's later battery-operated counterpart, the QT-8B) to affluent executives as the perfect briefcase wonder to help them grind through their latest business figures, as well as helping to manage their own personal finances.
Inside the Sharp QT-8DMoving inside the machine, the QT-8D is truly a marvel of electronics in its day. The entire guts of the calculator fit on two circuit boards, stacked one atop the other, both plugged into an edge-connector backplane that interconnects the boards. The backplane itself is a small printed circuit board with traces connecting the various edge connector pins. The circuit boards are made of phenolic, with traces on both sides of the boards, and components only on the top surface. Plated-through (along with solder-filled) feed-throughs provide interconnection between the two sides of each board.
The Unique Digit Rendition of the Itron DisplayThe top circuit board contains the display subsystem, consisting of the unique 8-segment Itron display tubes, discrete transistor display driver circuitry, and a single hybrid device that also helps with display driving duties.
The Iseden-made "Itron" Display Tubes in the QT-8DThe display consists of eight of the eight-segment Itron DG10B tubes made by Japanese manufacturer Iseden, which form numerals using an unsual arrangement of segments that make the numbers look very stylized. The most unique digit rendition is that of the digit zero, which looks kind of like a squashed, half-height zero. A special ninth tube, also made by Iseden (part number SP10), is positioned at the right end of the display panel, contains a "dot" and a minus-sign. The dot lights to indicate an overflow condition, and the minus sign lights to indicate a negative number in the display.
The Main Calculating Circuit Board of the QT-8DThe bottom board in the stack contains the main brains of the machine, with the Rockwell-made LSI chipset, along with the clock generator chip (in a can-type package), and a single Hitachi HD3103(Quintuple P-Channel MOSFET Transistors) IC providing some support circuitry.
A Closeup View of one of the LSI's in the QT-8DThe four LSI's are packaged in ceramic staggered pin flat-pack carriers, with each package having 42 pins. The part numbers on the IC's are AC2261, AU2271, NRD2256, and DC2266. The AU2271 chip (which has 900 transistors) contains the arithmetic unit, consisting of adder, complementer, binary to BCD (Binary-Coded Decimal) correction, and carry logic. The AU chip also hosts the working registers of the calculator. The AC2261 (AC stands for Address Control) chip is the master control, overseeing the interactions of the other chips. The NRD2256 chip (for Numeric Read-in/Display) uses 900 transistors to generate basic timing signals, manages scanning the display, and encodes keypresses from the keyboard. Lastly, the DC2266 chip (with 740 transistors) takes care of the logic to keep track of decimal point positioning. These same chips were used in another groundbreaking machine made by Sharp, the EL-8, the first "handheld", rechargeable battery-powered electronic calculator. The chips in the exhibited calculator all have date codes from the mid part of 1970, and the serial number of the machine indicates that it was built in July of 1970.
Keyboard Arrangement on the QT-8D
The QT-8D uses an unusual keyboard layout. Note the combined [X÷] key. Sharp used a novel means to save a key on the keyboard (thus saving the cost, as well as decreasing the real-estate needed for the keyboard) by making the [X÷] key serve both functions. The determination as to which function the user wishes is made by the user selecting either the [+=] key to generate the result for multiplication, and the [-=] key to cause division to occur. For example, to multiply, the user would enter the first number, press the [X÷] key, then enter the multiplier, then press the [+=] key for the answer. To divide, the user would enter the dividend, press the [X÷] key, enter the divisor, and press the [-=] key to calculate the answer.
The keyboard uses magnetic reed switches. This is one of the most expensive means for implementing a keyboard, but is extremely reliable. The magnet/reed switch design results in a keyboard that still works perfectly over 40 years later, with no double entry or incosistent operation problems. The keyboard assembly connects to the backplane via a neatly bundled wire harness. The keycaps have molded-in nomenclature, and are made of high-quality plastic. The keyboard has a great feel to it. Sharp's calculators tended to always have very nice keyboards, and the QT-8D is no exception.
The rear part of the calculator contains the power supply electronics. The machine uses a traditional transformer/rectifier setup, with transistor regulation. The power supply, like all of the other parts of the machine, is of high quality, using large filter capacitors and generous heatsinking. A special three-prong cord plugs into a socket on the rear panel of the machine.
The QT-8D is a relatively fast calculator, even though it is using early MOS LSI technology. The "all-nines" divided by one benchmark takes about 0.2 second to perform. Addition and subtraction complete with virtually no delay. The machine properly handles negative numbers, lighting the "-" indication in the special tube at the right end of the display. The machine also accurately detects overflow, lighting the 'dot' indicator at the right end of the display. The QT-8D does not detect divide by zero properly, and goes into a strange state which requires the machine to be cleared with the [C] key before it will return to normal operation.
Facit's OEM customer version of the QT-8D, the Facit 1115
Image Courtesy Serge Devidts, Calcuseum
Like many other Sharp calculators, the QT-8D was offered to Sharp's OEM customers for repackaging and sale by other manufacturers. Included among these were long-time Sharp OEM customer Facit, with the Facit 1115, as well as Facit subsidiary Addo-X, with the model 9354. The OEM versions of the QT-8D were identical inside, with the main differences being cabinetry styling, color scheme, and badging.
The Sharp QT-8D also appears to have a place in electronic calculator history within the former Soviet Union. A Soviet copy of the QT-8D, called the Electronika 24-71, was developed by the Soviets reverse-engineering the QT-8D. Leadership of the Soviet Union had become very concerned about the state of electronics within the Union in the 1960's. Many Soviet military systems still utilized vacuum tubes, and had only recently began utilizing solid-state (transistor) devices. The Soviet Union only had small-scale microelectronic devices in laboratory facilities, which were generally copies of devices developed in Europe and the United States. Large Scale Integration, which had started to make potential inroads into consumer electronics as early as 1965 in the US, and by late 1967 in Japan, was only a gleam in the eye of Soviet technical leadership. An aggressive program was put into place in 1969, with a promise made to then Soviet President Leonid Breshnev that he would have a Soviet-made Large-Scale Integration-based calculator on his desktop at the opening of the 24th Communist Party Congress in 1971. (Note the Soviet machine's model number of 24-71 was based on the 24th Congress, and 1971). The Soviet scientists and engineers were successful in duplicating the LSI chips themselves, but had difficulty with packaging them. In order to make the presentation to President Breshnev as promised, a Sharp QT-8D was acquired, disassembled, and its electronic guts repackaged into a Soviet-made cabinet, with a Soviet-made display based on the Japanese-design Itron vacuum-fluorescent display tubes used in the QT-8D (with a comma instead of a decimal point), and a Soviet-made keyboard assembly with Cyrillic keycaps. Soviet President Breshnev had no idea that his prized posession was just a repackaged Japanese calculator. It took until 1973 before the chip packaging issues had been solved, and the calculator went into production and sales, with a selling price of 100 Rubles (about US$85 back them).
Original Vendor's Sticker
This particular example of the QT-8D appears to have been purchased new in Boston, Massachusetts, at a business machine merchant called "I.C.B.M.". The vendor affixed a tag with their name, address, and telephone number on the side of the calculator case near the power switch. It seems ironic that a business machine company would name themselves ICBM, given that at the time, the threat of a nuclear attack by Soviet Inter-Continental Ballistic Missiles (ICBMs) was a very scary concern throughout the US military, as well as the population in general.