Looking for docs / schematics for MITS 88-HDSK and its associated Pertec drive

Josh Dersch derschjo at gmail.com
Wed Jun 10 23:23:28 CDT 2015

Hey all --

I'm assisting in the restoration of an Altair 8800 system which includes 
the MITS 88-HDSK ("Altair Hard Drive Controller") and Pertec D-3422 
removable pack/fixed platter drive  and after cleaning everything up, 
rebuilding supplies, etc, the drive spins up and goes Ready but all 
attempts to boot end in "LOAD ERROR: 1" which I have been told indicates 
that the Altair doesn't think the drive is ready.

I can't find any substantial documentation on the controller (the D-3400 
series is covered on bitsavers); I've checked with the Altair Computer 
Club and they don't have any docs posted (and the one guy who might have 
a copy of the docs is on vacation until the 12th, which wouldn't 
normally be a big deal but we're trying (perhaps in vain) to get this 
thing ready for an event on Saturday...).

Anyone have any docs or any other information for the 88-HDISK controller?


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