The system offers some Unix-like functionality including pre-emptive multitasking, multithreading, semaphores, signals, binary relocation, TCP/IP networking via SLIP, and a 6502 standard library.

[citation needed] Due to the small fixed-location stack of the 6502, and because an external MMU is rarely provided, multitasking is somewhat limited.

[citation needed] This can be increased to sixteen tasks when stack snapshotting is enabled, although this is done at the expense of some system speed.

[3] While early versions of Unix ran on for example early model PDP-11 computers that were comparable to Commodore 64 in terms of memory and processor performance there were architecture differences in terms of lack of a kernel mode, only 3 8-bit registers versus eight 16-bit general registers, and a fixed stack.

GeckOS arguably is more complete in some respects, with ACE being stronger in terms of standard Unix utilities but weaker in the operating system area.