QDOS is the multitasking operating system found on the Sinclair QL personal computer and its clones.
[1] Facilities provided by QDOS included management of processes (or "jobs" in QDOS terminology), memory allocation, and an extensible "redirectable I/O system", providing a generic framework for filesystems and device drivers.
This, and several other features, were never fully implemented in the released versions of QDOS, but were improved in later extensions to the operating system produced by Tebby's own company, QJUMP.
Rewritten, enhanced versions of QDOS were also developed, including Laurence Reeves' Minerva and Tebby's SMS2 and SMSQ/E.
All MG firmware versions shared the same bottom 32 KB ROM chip.