Reference STATE OF THE ART Stan Augarten

ISBN 0-89919-195-9

Photo of
A Popular Personal Computer Microprocessor
The 6502


Many of the most popular personal computers, including those made by Atari, Apple Computer, and Commodore International, use this exceptionally fast, inexpensive, and powerful microprocessor. The 6502 has an impressive heritage, having been modeled on another highly successful microprocessor, the 6800 from Motorola, which was in turn predicated on the seminal Intel 8080 (p. 36). Not surprisingly, the 6502 was created by a group of engineers who had been on the 6800 design team, and who had left Motorola to found a semiconductor firm of their own.

  The 6502's success lies, in part, in its synergistic combination of computational strength and low cost. Linked with certain memory and input/output chips, it can be turned into a sophisticated small-to-medium-sized computer with a minimum number of components. It requires only +5 volts of power, whereas most other 8-bit microprocessors need three power inputs (typically -5, +5, and +9 volts). The major advantage of a single power input is not a savings of electricity for the user, but a freeing-up of two of the chip's terminals for other processing chores.

  The 6502 was designed by MOS Technology (the acronym stands for metal-oxide-semiconductor; see p. 12), a company founded by former Motorola engineers and now a part of Commodore International, a personal computer manufacturer. But the 6502 depicted on the opposite page was manufactured by Synertek, a chip-making firm owned by Honeywell. Synertek is a so-called second source, fabricating the 6502 under a license from MOS Technology.

Used in many home computers, the 6502 can address up to 64K bytes of memory and add two 8-bit numbers in about a millionth of a second; it multiplies by repeated addition. The long narrow rectangular feature on the right is a register; the remainder of the chip is taken up by arithmetic and logic circuits. Actual size: 0.138 x 0.151 inches. Photo of


©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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