Intel MDS-740 hard disk documentation wanted

Eric Smith spacewar at
Mon Jun 15 03:45:21 CDT 2015

Does anyone have documentation for the Intel MDS-740 hard disk system
for use with the MDS and Series II, Series III development systems?
The drive had one fixed and one removable platter, the removable being
a 12-sector 5440-style cartridge. The drive may have been a CDC 9427H,
or something similar.  The controller was two Multibus boards, a 3000
bit-slice based channel board, and a drive interface board. (Similar
organization to the two-board floppy controllers.)

I am mostly looking for the schematics and programming information,
though if anyone has an actual controller board (or even just the
channel board), a dump of the microcode would be useful.

The documentation I'm looking for might or might not be contained in
the "Model 740 Hard Disk Subsystem Operation and Checkout" manual,
order number 9800943A.

Note that this is *entirely* different than the iMDX 750 winchester
disk subsystem.  The 740 was supported by plain ISIS-II 4.x, while the
iMDS 750 used a variant of the iSBC 215 controller, and required a
special ISIS-II(W).


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