GeckOS

GeckOS is a multitasking, Unix-like operating system for the MOS 6502 processor and compatible chips such as the 6510, written by Andre Fachat. It offers preemptive multitasking, multithreading, semaphores, signals, binary relocation and TCP/IP networking over SLIP, along with a 6502 standard library, and its kernel design was written to be easy to port to other 6502-based machines. GeckOS runs on the Commodore PET, in both 32 kilobyte and 96 kilobyte configurations, on the Commodore 64, and on the homebrew CS/A65 computer. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/