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Corporate information

MOS Technologies was a microprocessor and calculator company famous for its 6502. It originally started up as a second source manufacturer for Texas Instruments electronic calculators and the chips inside them. They also produced Atari's custom PONG chip. As the calculator market grew MOS eventually became largely beholden to Commodore, who bought practically all of their supply for their line of calculators.

In 1975 several of the designers of the 6800 left Motorola shortly after its release. At MOS they set about building a new CPU that would outperform the 6800 while being similar to it in purpose. The resulting 6501 was simpler than the 6800 but up to four times faster.

In September 1975 the successor 6502 was released. Due to its speed it outran the more complex and expensive 6800, Intel 8080 and Zilog Z80 series, but cost much less and was easier to work with.

The 6502 would quickly go on to be one of the most popular chips of its day. A number of companies licensed the 650x line from MOS, including Rockwell and Synertek.

However successful the 6502 was, the company itself was having problems. At about the time the CPU was released the entire calculator market collapsed, and MOS's only existing products stopped shipping. Soon they were in serious financial trouble. Rescue came in the form of Commodore, who bought the entire company in a stock trade. The company name MOS was held for some more years and later changed to Commodore Semiconductor Group (CSG).

MOS had also designed a simple computer kit called the KIM-1, primarily to show off the 6502 chip. A re-packaged KIM with a new display driver and keyboard became the Commodore PET computer.

Chip markings:
  add/correct MOS info  
18 MOS chips in collection: show thumbnails
   MPS 6502
   6502 A
   6502 B
   CSG 8500
 650x peripheral
   650x peripheral MCS 6540
   650x peripheral 6526
   650x peripheral 6522
   650x peripheral 6529B
   650x peripheral 6526A-1
   650x peripheral 6526 (CSG)