pdp-20

PDP-20
 n.

   The most famous computer that never was. {PDP-10} computers running
   the {TOPS-10} operating system were labeled `DECsystem-10' as a way of
   differentiating them from the {PDP-11}. Later on, those systems
   running {TOPS-20} were labeled `DECSYSTEM-20' (the block capitals
   being the result of a lawsuit brought against DEC by Singer, which
   once made a computer called `system-10'), but contrary to popular lore
   there was never a `PDP-20'; the only difference between a 10 and a 20
   was the operating system and the color of the paint. Most (but not
   all) machines sold to run TOPS-10 were painted `Basil Blue', whereas
   most TOPS-20 machines were painted `Chinese Red' (often mistakenly
   called orange).
    

PDP-20

   The most famous computer that never was.  {PDP-10} computers
   running the {TOPS-10} operating system were labelled
   "DECsystem-10" as a way of differentiating them from the
   {PDP-11}.  Later on, those systems running {TOPS-20} were
   labelled "DECSYSTEM-20" (the block capitals being the result
   of a lawsuit brought against DEC by Singer, which once made a
   computer called "system-10"), but contrary to popular lore
   there was never a "PDP-20"; the only difference between a 10
   and a 20 was the {operating system} and the colour of the
   paint.  Most (but not all) machines sold to run {TOPS-10} were
   painted "Basil Blue", whereas most TOPS-20 machines were
   painted "Chinese Red" (often mistakenly called orange).

   [{Jargon File}]

   (1994-12-21)