The Apple II and Commodore 64 are the obvious ones but which other computer systems used the 6502 and 65816 chips?
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There is a Wikipedia category that aims to list them, at least, the home computers part. https://en.wikipedia.org/wiki/Category:6502-based_home_computers
The current list of home computers is as follow:
Acorn Atom Acorn Electron Acorn Eurocard systems Acorn System 1 Acorn System 2 Acorn System 3 Acorn System 4 Acorn System 5 Atari 8-bit family
BBC Master BBC Micro
C-One Commodore 128 Commodore 64 Commodore LCD Commodore MAX Machine Commodore PET Commodore VIC-20 Compukit UK101
Ohio Scientific Oric
Tangerine Microtan 65
There is a list that seems to be more exhaustive, at: http://www.dwheeler.com/6502/oneelkruns/65machines.html
Apple I Apple II Apple II+ Apple III Apple IIe Apple IIc Apple IIc+ Commodore PET Commodore VIC-20 Commodore 64 Commodore 128 Commodore Plus/4 Atari 400 Atari 800 Atari 800XL Atari 1200XL Atari 600XL Atari 65XE Atari 130XE Atari XE-GS Atari 5200 (game system) Atari 7800 (game system) Atari 2600 (game system) Atari Lynx 1 and 2 (game systems) Laser 128 MOS Technologies KIM-1 SYM-1 (similar to KIM-1) JOLT (had an ad in Dec. 1975 Byte magazine, anyone have one?) Rockwell AIM-65 Oric-1 Oric Atmos Oric Telestrat Tangerine Microtan-65 Acorn System One Acorn Atom Acorn BBC-A Acorn BBC-B+ Acorn BBC-B Acorn Electron Nintendo Entertainment System (original 8-bit) Atari Lynx PC-Engine (Turbo Grafix 16) (two 6502s) OSI Superboard 600 / UK 101 Vtech creatiVision Laser 128 Laser 128EX Laser 3000
There is another machine from Video Technology that used the 6502, the Laser 2001. In a way this was the successor to the CreatiVision, a hybrid computer and home video game console introduced by VTech in 1981. As such, the Creativision used the 6502 as well.