|Reference||STATE OF THE ART||Stan Augarten|
|The First 16-Bit Microprocessor|
In an effort to pass the competition and gain a foothold in a potentially large market, National Semiconductor, a Fairchild offshoot that became one of the largest chip-makers in the United States, introduced the first 16-bit microprocessor in 1974. The chip was christened PACE, for Processing and Control Element, and was, by the rapidly changing standards of the industry, unpardonably slow. Although it failed to catch on, it was, however, a taste of things to come.
The trouble with PACE was that it was made out of hole-doped MOS transistors, and positive ions move through silicon at about a third the speed of electrons (p. 12). PACE carried out a single operation in some ten millionths of a second, about four times the time required by the first electron-doped 16-bit microprocessors. By using hole-doped transistors, an established technology, National's engineers were playing it safe; but by the time their chip appeared, the IC industry was making efficient electron-doped microprocessors, and PACE soon became obsolete.
Sixteen-bit microprocessors like PACE can process far more data than 4- and 8-bit chips; they are much too powerful for handheld calculators and most video games, and are more suitable for advanced personal computers and industrial control equipment. PACE was a valiant effort, but it wasn't until the late 1970s that chip technology advanced to the point where efficient and potent 16-bit microprocessors were possible (see the 68000 from Motorola, p. 58).
|Set on the base of a well in the center of a thin rectangular ceramic package, PACE is firmly bonded in place with gold and is liked to the surrounding rectangular connectors by aluminum wires 0.002 inches thick. The connectors extend through the ceramic to forty leglike prongs (not shown here) that plug into circuit boards. The well is normally covered with a protective plate. The ceramic package measures 11/16 x 2 x 1/16 inches, and the chip is 0.250 inches square.|
|STATE OF THE ART
©Copyright Stan Augarten
|This book is provided for general reference. The National Museum of American History and the Smithsonian Institution make no claims as to the accuracy or completeness of this work.|
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