--On Sunday, February 27, 2011 10:48 AM -0800 John R Pierce pierce@hogranch.com wrote:
the PDP-10 was in fact considered a mainframe in the 1960s. They were more commonly called DECsystem-10, or KA10, KL10. the CPU was multiple cabinets, the KL10 supported up to 4 megawords of ram (where a word was 36 bits). They were commonly used as timesharing systems which was relatively uncommon in the late 1960s
https://secure.wikimedia.org/wikipedia/en/wiki/PDP-10
I used them at MIT in the early 80's and also at Systems Concepts, which designed a clone.