On Sun, Dec 6, 2020 at 7:51 PM Fred Cisin via cctalk <[email protected]> wrote:
> On Sun, 6 Dec 2020, Chris Zach via cctalk wrote: > > 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. > The mfm emulator at https://www.pdp8.net/mfm/mfm.shtml by David Gesswein will read them all, though... Warner
