News Archive - Pre-Introduction Article on Technology used in Sharp micro-Compet QT-8D
Electronics Magazine, March 17, 1969
Early Pre-Introduction Article for the Hayakawa Electric Sharp QT-8D
The QT-8D was touted as the smallest fully-featured (e.g., add/subtract/multiply and divide) electronic calculator in the world when it was formally introduced at the IEEE exhibition in New York, NY on March 27, 1969. Hayakawa Electric was able to make the calculator so small by utilizing advanced MOS Large Scale Integration (LSI) chips jointly developed by Hayakawa Electric and the Autonetics division of North American Rockwell in the US. Hayakawa Electric had created a logic design for an eight digit automatic floating decimal calculator, and this design was used as the basis for developing the four LSI chips that contain all of the logic to make the calculator function.
The chips were manufactured in the US by Autonetics, then shipped to Hayakawa Electric as unpackaged chips and Hayakawa Electric would place the chips in ceramic packages and wire up the bond-out connections to connect the chip to the pins on the package, then seal the chip under a circular metal lid that is soldered to a gold perimeter of a hole in the top of the ceramic package.
Along with the four logic chips, Autonetics also developed a special clock driver chip packaged in a TO-100 metal can-type package that provides the necessary drive current for the four-phase clocking system used by the chips.
The Sharp QT-8D is historically significant in that it is considered the first commercially successful electronic calculator to utilize MOS/Large Scale Integration integrated circuits for the entirety of its logic. That said, the Victor 3900, introduced over three years earlier, had all of its logic contained in 29 MOS/LSI chips.
The Victor 3900 had twenty digits of capacity, two memory registers, and a CRT display that showed the content of all three working registers, as well as the content of the two memory registers continually. There was considerably more logic required to implement the Victor 3900 than was needed for the QT-8D, but the MOS integrated circuit technology was considerably more advanced by the time the development of the QT-8D came along.
While the QT-8D is considered by history as being the first, technically the Victor 3900 really holds the title. The problem with the Victor 3900 was that it was plagued with delays during the development of the LSI chips under contract to General Micro-electronics. After the development issues were sorted out, problems with chips developed after the calculators were sold to customers, requiring many of them to be shipped back to General Micro-electronics to be reworked, leaving the customer without their expensive calculator for considerable periods of time.. Eventually the 3900 accumulated enough of a word of mouth reputation as being troublesome that its sales were not at all at the level necessary to realize any profit. It was an expensive calculator due to its technology and features, but there were calculators on the market by the time that the 3900 was getting into the hands of customers that had similar features, and cost considerably less, which made it even more difficult for Victor Comptometer's salespeople to sell the 3900 against the competition.
This is why the QT-8D is considered the first, because the Victor 3900, though it was technologically way ahead of its time, it simply didn't sell well enough to be considered a success.
For more information on the story of the Victor 3900, see the Old Calculator Museum's essay on the calculator and its development.