Although the company eventually released a PC with a CD-ROM drive in 1991, the Commodore 64’s heyday was long before CD-ROMs ...

So he set about turning his C64 into one instead. He decided to use the pins of the C64’s Joystick Port 2, with pins 1, 2, 3, and 4 hooked up to SCK, MOSI, Reset, and MISO on the AVR ...

The keyboard will also be replaced at some later point, and items like the joystick ports were salvaged from an old C64 rather than purchased brand new. None of which are fundamental problems ...