QDOS

from The Free On-line Dictionary of Computing (8 July 2008)
QDOS

   <operating system> The Sinclair {QL}'s proprietary {operating
   system}.  The origin of the name is uncertain (a weak pun on
   kudos, perhaps, as {Unix} was on {Multics}).  There was
   another OS around from the birth of personal computers called
   Q.D.O.S. - Quick And Dirty Operating System.  QDOS might also
   stand for QL Data/Disk/Drive/Device Operating System.

   QDOS did the usual OS sorts of things, as well as
   multitasking.  It was unusual in several ways.  It treated all
   devices (serial ports, mouse ports, screen, {microdrive},
   {disk drive}, keyboard, etc.) uniformly, so you could print a
   text file direct to disk or save a binary to the screen for
   example.

   Also logical channels could be assigned to particular physical
   devices.  Output directed to a channel would go to the
   appropriate in/output.  This also meant you could have many
   windows on screen (the QL booted up from internal ROMs with 3
   windows - command line, output and program listing) all
   independent to some extent.  Channels could be redirected
   without affecting the way the process sent or received the
   data.

   (1996-07-22)