A 65C02 and an ATmega4809 make a functional two-chip computer
Colin Maykish’s weekend experiment resulted in a two-chip, eight-bit computer, the VR65C02. This minimal build features an actual 65C02 microprocessor and an eight-bit ATmega4809 AVR microcontroller (MCU). The 65C02 is the computer’s CPU, running 6502-native code, while the AVR effectively emulates the computer’s RAM, ROM, and I/O devices.
The Microchip ATmega4809 is the same AVR MCU used in the updated Arduino Nano Every. The megaAVR processor has 6 kilobytes of RAM, 48 kilobytes of Flash, and up to 31 dedicated GPIOs in the 40-pin DIP variant.
The build script, Arduino sketch, and Python utility are available in the VR65C02 GitHub repository. That repo also contains an excellent write-up detailing the interaction between the AVR and 65C02. Additional information is available on this project page and on hackster.io.
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