CDC 6600 - Why so awesome?

Paul Koning paulkoning at
Wed Jun 22 20:18:51 CDT 2016

> On Wed, 22 Jun 2016, Chuck Guzis wrote:
> ...
>> Its illegitimate relative, KRONOS, made extensive use of ECS for support 
>> of the PLATO system. 

Not quite.  KRONOS treated ECS (rather clumsily) as a kind of disk.  PLATO just bypassed all that and managed ECS directly, as memory the way it was originally designed to be used.  After startup, PLATO would own all the ECS and do transfers directly, without any OS involvement.  It would also use ECS for inter-job communication, and for communication with PPU programs.  For example, PLATO disk I/O uses both request queues and data buffers in ECS, which the PPU program accesses.  Ditto for terminal I/O.

This is how PLATO could support 600 logged in highly interactive users on a pair of 6500 (low end 6000 series, single issue) machines.


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