SymbOS is a free multitasking operating system for Z80-based 8-bit computer systems. / it is based on a small kernel, which provides pre-emptive and priority oriented multitasking and manages RAM with a size of up to 1024 kB. SymbOS contains a / Graphical user interface, supports hard disks with a capacity of up to 128 GB and can already be booted on an unexpanded Amstrad CPC-6128, a 128K-MSX2 and an Amstrad PCW.
/ the Z80 is capable of running a pre-emptive multitasking operating system. Features such as memory protection, which the Z80 does not support, are not essential in such an OS. For example, AmigaOS does not feature memory protection either. The MP/M OS proved that multitasking on the Z80 CPU was possible /
While the MOS Technology 6502 cannot move the stack pointer, the Z80 can freely relocate it to any position in memory, which is more or less a requirement for pre-emptive multitasking. The existence of an alternative register set accelerates context switching between tasks dramatically. The restriction of Z80 system to a 64 kB address space can be solved with bank switching. / able to access hundreds or thousands of kilobytes of memory.
