7 Jun
2014
7 Jun
'14
10:21 p.m.
I wrote:
The drives are MPI part no. 77618022, apparently a
9406 variant but not
listed in the drive manual on Bitsavers. I suspect the pinout is close to
the SA800/850 pinout (industry standard), but I was surprised to find that
none of the variants in the 9406 manual have a pinout similar to that.
I figured out how to extract the drives. The chassis is not designed to
make it easy; you have to remove the key switch and "Quay" faceplate, which
extends downward just enough to block sliding the drive out the front.
Both drives are the 77618022 variant, with PWA (PCB) P/N 77615454, which is
not described in the manual. It has a few less ICs and several more
potentiometers than the PWAs in the manual.
The drives appear to have been manufactured in late 1979, so it seems odd
that they wouldn't be in the mid-1982 9406 manual.