On 9/23/22 11:41, Paul Koning wrote:
> 

> Another way to get high speed: one of CDC's first disk drives, the 6603, 
> wrote several bits in parallel.  4 bits?  12?  I don't remember, but it made 
> for a throughput spec that was unbeaten for nearly a decade.

I think the 6638 was the controller you may be thinking of; the drive
was the 808 (and 821 if you're after arcana).  The 6603 was the old
Bryant 4000 disk.  I've got a head from one (808)--6 channels quite
visible.  Each head assembly had several heads.  4 spindles with 2
actuators (hydraulic), one on top and the other on the bottom, with the
actuator sitting between the spindles, so accessed in a sort of
pushme-pullyu arrangemt.  Transfers, of course, were 12 bits wide.

The 821, which I never saw outside of Special Systems Divison, increased
the capacity.  It was notoriously unreliable with a tendency to go "not
ready" without notice.  Otherwise, it was the tall gray cabinet that
looked exactly like an 808.

--Chuck


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