Using the Apple 1 as inspiration for a DIY 6502-based computer. It runs Steve Wozniak’s original ‘Woz monitor’ and BASIC written for the Apple 1 in 1976 (41 years ago!) with a few modifications to allow for communications through a serial port (enabled with use of a HD6350 ACIA IC) instead of a TV and ASCII keyboard.

An ATtiny2313A is used to generate the serial tx/rx clocks required by the ACIA by dividing a 7.3728MHz crystal down to 300Hz (it also debounces the ‘single step’ button and derives the system clock, currently @ 2kHz though this will be higher in the future).

Features:

  • Rockwell R65C02 CPU - CMOS variant of 6502
  • 8K SRAM
  • 32K EEPROM (of which 8K currently accessible).
  • single steppable