PDP-20
/pē-dē-pē-twen-tē/
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).
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