MOS 6502

The MOS Technology 6502, often simply referred to as 6502, was a low-cost 8-bit processor that was produced by, and later. It became widely used in early computers, such as the Apple I, and, as well as early game systems, such as the.

History
Electrical engineer had worked on the  processor in 1973, which was priced at 300 per unit in a kit. Motorola turned down his proposal to produce a simplified processor to meet marketplace demand for a lower-cost processor. Peddle and some other Motorola engineers then left for MOS Technology, where they formed a small team to design the 6502, which became available in 1975 at a fraction of the cost of the Motorola 6800 and.

In November 1975, Motorola filed a lawsuit against MOS Technology for patent infringement and misappropriation of trade secrets. MOS settled the case in March 1976 for $200,000 and cancelling the 6501 processor, which was socket-compatible with the 6800. In November 1976, MOS was acquired by Commodore International, which produced the 6502 and variants for its own computer line.

Steve Wozniak obtained early units of the 6502 from Chuck Peddle for use in the Apple I computer. After Commodore acquired MOS, Apple obtained subsequent processors from for their Apple II and III series.

Variants
The 6502 design was revised many times and licensed to different manufacturers:
 * MOS MCS6502 - a rare early version of the MOS 6502 which was used in the Apple I computer.
 * SY6502 - a d version used in Apple II computers after MOS was acquired by Commodore.
 * Synertek SY6502A/B - a faster version used in Apple III computers.
 * MOS 6502B/C - even faster versions used in the, , , and.
 * NCR/GTE - a low-power CMOS version used in the Apple IIc and Apple IIe.
 * - an ultra low-cost version used in the.
 * - an enhanced version used in the.
 * WDC 65C816 - a backwards-compatible 16-bit version used in the Apple II GS.

Articles

 * How The Dis-integrated 6502 Came To Be by Mike Szczys at Hackaday (2016-05-24)
 * The Good Old 6502 Microprocessor, But 7000x Bigger! by Farhad Modaresi at The Journal of Science and Technology (2020-10-15)