MOS 6501

The MOS Technology MCS6501, also simply referred to as 6501, was a low-cost 8-bit processor that was briefly produced by. However, it was overshadowed by its widely-adopted successor, the MOS 6502.

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 MOS 6501 and 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, which produced the 6502 and variants for its own computer line.

Steve Wozniak obtained early units of the 6501 for use in the Apple Computer A prototype. For production units of the Apple-1 computer that shipped in 1976, Wozniak said that the processor was switched from the 6501 to the 6502 with its improved transistors because "by real production time we could get the 6502 for the same cost".