GeckOS is an experimental operating system for MOS 6502 and compatible processors. It offers some Unix-like functionality including preemptive multitasking, multithreading, semaphores, signals, binary relocation, TCP/IP networking via SLIP and a 6502 standard library.

Geckos are lizards belonging to the infraorder Gekkota, found in warm climates throughout the world. They range from 1.6 to 60 cm (0.64 to 24 inches). Most geckos cannot blink, but they often lick their eyes to keep them clean and moist. They have a fixed lens within each iris that enlarges in darkness to let in more light.