17 Jul
2009
17 Jul
'09
2:34 p.m.
On 16 Jul 2009 at 7:01, Chris Elmquist wrote:
Yes... the Micropolis controller design, which VG and
Multi-Tech
clearly used as a reference design, is a 16-hole hard sector thing.
Multi-Tech also had a GCR controller but I don't
have one of those.
It was a board chock full of parts including a Z80 I think. It was a
PITA to align and very expensive so I opt'd not to obtain one as a
parting gift from Multi-Tech.
I think I have a couple of Multi-Tech diskette samples in my files.
The GCR design was also used by Future Data in 8" format for their
CAD workstations.
Does anyone have any documentation for the Micropolis demo system? I
can recall seeing it back then, but I ddn't pay much attention to it
and didn't save any of the paper.
In any case, ours was complicated--the controller for our system
took up an entire Multibus-sized board. In retrospect, that was
probably thought not to be too bad, when viewed in the light of the
floppy controller that was being supplied with the Intel MDS-800--two
boards with Intel 3000-series bit-slice logic on one.
The design for ours was done by an engineer we hijacked from Sperry
ISS who did work on big-iron drives The WD1781 was buggy (had a
tendency to hang) and WD got tired of making it. On the next system
design, we used 96 tpi drives and MFM. Customers were disappointed
in getting 800K (10x512 tracks) instead of 980K (12x512) on their
floppies, but it was much cheaper, required no adjustment and could
be tucked into a corner of a board. By then, they were using hard
disks anyway.
We found that Micropolis was very sloppy when it came to head azimuth
on drives from the factory and it took some table-pounding for them
to get their act in shape.
--Chuck