MOS Technology 6502

From TekWiki
Jump to navigation Jump to search
6502AD (click to enlarge)
6502AD (click to enlarge)

The MOS Technology 6502 is an 8-bit microprocessor monolithic integrated circuit introduced in 1975 that was originally developed by a team led by the engineer Chuck Peddle at MOS Technology (later purchased by Commodore).

It was second-sourced by other companies such as California Micro Devices (GTE Microcircuits), Rockwell, and Synertek. Western Design Center (WDC) first developed a CMOS version, which is still in production as of 2019. In addition, several implementations (commercial as well as free) are available to synthesize the core into FPGA designs.

The 6502 was a popular choice of processor because of its low price and high capabilities. It was used in multiple early computers such as the Commodore 64, Commodore VIC-20, Apple II, BBC micro, and many others.


The 6502 had many revisions and derivatives. Most of the revisions have either enhanced its capabilities or have added new features.

Depending on the manufacturer, the fabrication process can be CMOS, HMOS and NMOS.

The 6502 has three registers, one main register and two index registers. The original MOS 6502 had 151 "legal" opcodes. Later version included more.

MOS 6502 registers
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 (bit position)
Main registers
  A Accumulator
Index registers
  X X index
  Y Y index
0  0  0  0  0  0  0  1 SP Stack Pointer
Program counter
PC Program Counter
Status register
  N V - B D I Z C P Processor flags

Used in

Some instruments using part MOS Technology 6502

Instrument Manufacturer Class Model Description Introduced
1220 Tektronix Logic Analyzer 1220 32 channel logic analyzer 1988
1225 Tektronix Logic Analyzer 1225 48 channel logic analyzer 1988
1230 Tektronix Logic Analyzer 1230 16 to 64 channel logic analyzer 1988
DC5009 Tektronix Plug-in DC5009 135 MHz programmable frequency counter 1982
DC5010 Tektronix Plug-in DC5010 350 MHz programmable frequency counter 1982
DC509 Tektronix Plug-in DC509 135 MHz programmable frequency counter 1981

Supported by