https://collapseos.org/

Collapse OS is a new open-source operating system built specifically for use during humanity's darkest days.

Collapse OS will work with Z80 8-bit microprocessors. Though less common today than 16- and 32-bit components, the 8-bit Z80 can be found in desktop computers, cash registers, musical instruments, graphing calculators, and everything in between. In a Reddit Q&A, Dupras explained that the Z80 was chosen "because it's been in production for so long and because it's been used in so many machines, scavenger have good chances of getting their hands on it.