6502 Assembly

The MOS Technology 6502 (and its variants) is an 8-bit CPU at the heart of many video game platforms including:

Platform	CPU
Apple I	MOS 6502
Apple II	MOS 6502
Apple IIc	WDC 65C02
Apple IIe	GTE 65C02
Atari 2600	MOS 6507
Atari 8-bit family	MOS 6502B
Atom	MOS 6502
BBC Micro	MOS 6502
Commodore 16	MOS 7501, MOS 8501
Commodore 64	MOS 6510, MOS 8500
Commodore 128	MOS 8502
Commodore PET	MOS 6502
Commodore Plus/4	MOS 7501, MOS 8501
Commodore VIC-20	MOS 6502
Electron	Synertek SY6502A
Famicom	Ricoh 2A03
Famicom Disk System	Ricoh 2C33
Lynx	WDC 65SC02
Nintendo Entertainment System	Ricoh 2A03 (NTSC), Ricoh 2A07 (PAL)
PlayChoice-10	Ricoh 2A03
TurboExpress	HuC6280
TurboGrafx-16	HuC6280
VS. System	Ricoh 2A03

If you want to do any major hacks to games on any of these systems, you must become familiar with the structure and function of 6502 machine code and assembly code.

Below are various guides that will help you understand and program the 6502.

• 6502 Beginner's Guide
• 6502 Opcodes
• Registers
• Addressing Modes
• Variables