"Contiki provides multitasking and a built-in Internet Protocol Suite (TCP/IP stack), yet needs only about 10 kilobytes of random-access memory (RAM) and 30 kilobytes of read-only memory (ROM).[1] A full system, including a graphical user interface, needs about 30 kilobytes of RAM.[5]"
"SYmbiosis Multitasking Based Operating System (SymbOS) is a multitasking operating system for Zilog Z80-based 8-bit computer systems. Contrary to early 8-bit operating systems it is based on a microkernel, which provides preemptive and priority-oriented multitasking and manages random-access memory (RAM) with a size of up to 1024 KB. SymbOS contains a Microsoft Windows like graphical user interface (GUI), 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."
"Although only an 8-bit CPU, the Z80 can run a preemptive multitasking operating system. Features such as memory protection, which the Z80 lacks, are not essential in such an OS. For example, AmigaOS also lacks memory protection. The MP/M OS proved that multitasking on the Z80 CPU was possible. Yet, it was generally unavailable for home computers."
