Help needed identifying old MFM drives from the excavation

Chuck Guzis cclist at
Mon Dec 7 13:16:53 CST 2020

On 12/7/20 10:32 AM, Paul Koning wrote:

> I know of the 6603, is that a controller and the 808 is the drive? 

The 6603 was the controller for the Bryant drive--I don't know if the
Bryant drive had an 800-series number.  But it used zoned recording.

The 808's controller was the 6638.  I still have a head from an 808,
salvaged from the detritus where the CEs were taking hammers and bolt
cutters to one (thank you Bill Norris).  I used to have a platter as
well, but that went by the wayside during a move.

A good description of the unit is in bitsavers:

I exaggerated a bit--the 808 was more than 6 feet, but less than 7 feet
tall (77 inches).  I recall only that I never saw the top of one without
a ladder.

The 808 had a relative, the 821, with about 4x capacity.   Other than
for internal testing and RFP responses, I don't think it was ever
released externally.   Basically 808-sized.  Had a terrible tendency to
go offline at the most inconvenient times.   Mike Miller on the original
Special Systems AF Logistics project saved the contract by doing a
sprint during the timed benchmark to punch a button on one that had gone

The 821 never made it into the final contract; it was replaced by many
of the then-new 844 removable-media drives.  Apparently, lots of small
drives were cheaper to source than monster drives.


> Pretty amazing drive.  12 bit parallel transfer, so the data rate was way faster than any other drive of that era (1964 or so).  It also did "zone recording" (more sectors per track on the outer tracks) well before that showed up in other drives

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