Western Design Center 65816

The 65816 (65C816) is a microprocessor designed by Western Design Center. It is an expanded version of the 6502, with which it is compatible. It has 16-bit index registers and stack pointer, a 16-bit direct page register and a 24-bit address bus. Western Design Center was founded in 1978 by co-holder of the 6502 patent, Bill Mensch, who himself was a former MOS Technologies employee.

Notable uses of the 65816

• as microprocessor in the Apple IIgs (2.8 MHz)
• in the Super Famicom/Super Nintendo video game consoles (3.58 MHz)
• in the SuperCPU accelerators for the Commodore 64 and 128 (20 MHz)

• A 6502 Programmer's Introduction to the 65816
  by Brett Tabke