PDP-20

   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).

[glossary]
[Reference(s) to this entry by made by: {DEC}{Internet}]