The 6502 microprocessor was developed by Chuck Peddle and Bill Mensch for MOS Technology in 1975. The chip was used in many computers like the Commodore PET, CBM and VIC-20, Atari, BBC, Apple etc. If you want to build your own computer with a 6502 you should look at the latest project from Blondihacks.

Demonstration video of the 6502 computer project.