Another mystery head quiz

Chuck Guzis cclist at
Thu Apr 23 15:13:54 CDT 2015

On 04/18/2015 04:44 PM, Chuck Guzis wrote:

> At any rate, who can identify the head in this photo:
> I'm pretty certain that I know.  It's about 16mm square and is mounted
> on a small PCB with lead connections.

Okay, nobody venturing a guess after a week...

This is one of the heads from a CDC 808 disk drive slider.  Note the 6 
channels.  I say that I'm "pretty certain" because this may also be a 
head from the ill-fated 821 disk drive, sort of a "super 808", with more 
storage.  I don't think the 821 ever made it into the wild, as it was 
shortly dumped in favor of the 844 "pack" drive that many know so well. 
  Since the CEs were trashing all sorts of equipment at the time I 
grabbed this, it's hard to say.

72 disk platters, two spindle motors, hydraulic positioners, water 
cooling and somewhere around 6 ft. tall.

I can't find a photo on the web, but I suspect there's one there.

Usually referred to generically as a "6638" or "6639" type drive, which 
was really the name of the controller, not the drive itself.

A brief overview of it can be found on Bitsavers:


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