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

Camiel Vanderhoeven iamcamiel at
Sat Apr 23 12:06:10 CDT 2016

Now that we're on the subject of 6600's and the like... I have a bit
of a puzzle. I have some CDC 7600 modules; these consist of 8 thin
PCB's, with metal shielding in between. On the back, there are 8 rows
of 16 pins, and on the front there are 8 rows of 6 recessed pins,
staggered (I believe for testing/debugging purposes). On the top and
bottom of the front is a tab with a screwhole in it, black like the
entire front of the modules, and as wide as the module it self. So far
so good, this matches all the photo's of 7600 modules I've seen

Now, I also have some modules that are the same form factor, same
number of pins in the back, but they're different. There's only 4
pcb's, no shielding between them, except in the middle, 4 x 8 pins in
the front, and the tabs on the top and bottom of the front are small
(not as wide as the module itself, and silver-colored. The pcb's are
not connected with soldered-in wiring, but with goldplated wires that
run between sockets in the pcb's. On the pcb's are loose transistors,
resistors, etc like in the 7600 modules, but also some square Fujitsu
ECL IC's (100550 and the like), with date codes that indicate 1983,
which sounds a bit late for a 7600.

Any idea what these modules might have been used in?


On Fri, Apr 22, 2016 at 2:50 AM, Paul Koning <paulkoning at> wrote:
>> 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
>         paul

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