RITSUmaker 6502 microprocessors The 6502 was a classic microprocessor used in 8-bit home computers such as the Commodore and the Atari, as well as the very first Apple computer. It was designed in the 1970s, over 40 years ago. In this project we created a complete 8-bit 6502-based microcomputer on a breadboard, using 32kB of RAM and 16kB of ROM. We use it for learning machine-code programming but it also runs one of the very first versions of Microsoft Basic, written in 1977.

RITSUmaker 6502 microprocessors Programming the ROM was another challenge of this project. We solved it by making an EEPROM programmer using an Aruino Mega computer. The program for the ROM is prepared using a 6502 assembler, and the hexadecimal machine code pasted into an Arduino sketch. The sketch is uploaded to the Arduino Mega which sends the right signals to the EEPROM to erase it and then write the hexadecimal machine code into it. The EEPROM is then plugged into the 6502 microcomputer, which runs the programmed code when it is switched on.