6 Dec
2020
6 Dec
'20
7 p.m.
On Sun, Dec 6, 2020 at 7:51 PM Fred Cisin via cctalk <cctalk at classiccmp.org>
wrote:
On Sun, 6 Dec 2020, Chris Zach via cctalk wrote:
The mfm emulator at https://www.pdp8.net/mfm/mfm.shtml by David Gesswein
will read them all, though...
Warner
As the excavation of Bob's junkpile continues
I have finally hit the MFM
layer. Specifically about 10 5.25 hard disks that look to be old style
MFM
drives.
Vertex V150
Miniscribe 6085
ST 4038M Seagate Franklin telecom AT-40
Miniscribe 3650 HH
Seagate ST4096
Priam ID45-H
Rodime RO203E
RD54
Real ST506
Pair of ST412's.
The Seagates were commodity drives, used in almost everything.
Number is approximately the unformatted capacity.
ST506 was 5MB formatted (305 Cyl x 2 heads) ;
ST412 added buffered seek, was 10MB formatted (306 cyl x 4 heads).
ST4096 was 80MB formatted. (1024 Cyl x 9 heads) For a long time, it was
the most common of the largest drives in that form factor. I found out
that 135W XT/AT power supplies were not always happy trying to run two of
those at a time.
XT/AT MFM had 17sectors per track; 512 bytes per sector.
Drives formatted on a machine other than 5160/5170 are likely to be
unreadable with 5160/5170.
Drives formatted for a given XT controller were often incompatible with
another XT controller. (Was some of that due to numbering sectors from 0
Vs from 1?)
Drives formatted with an AT controller were normally usable on another AT
controller.