CDC 6600/Cyber 73 Memories - WAS: Harris H800 Computer

Paul Koning paulkoning at
Thu Apr 21 19:50:36 CDT 2016

> On Apr 21, 2016, at 7:33 PM, Chuck Guzis <cclist at> wrote:
> ...
>> Neat.  PLATO made extensive use of ECS, swapping per-terminal state
>> and programs in and out of ECS for fast interactive service.  ECS was
>> also where most I/O buffers went, with PPUs doing disk and terminal
>> I/O from/to ECS rather than central memory.  A dual mainframe 6500
>> system (4 "unified" processors total) did a decent job supporting 600
>> concurrent logged-in terminals, out of a total of 1008 connected.
>> That was around 1977 when I worked on that system at the U of
>> Illinois.
> Was that UIUC?  I processed some CYBER tapes from there a couple of
> years ago--there's an archivist there who uses us to retrieve contents
> of various dusty items.

Yup.  A couple of us helped put the PLATO copy running on the DtCyber emulator together, see


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