hard drive history

beginings: mfm drives of the 1980s

Seagate ST-251-1

Photo: Red Hill.

Seagate ST-251

Another grand old soldier of the MFM era.

Like the notorious Miniscribe 3650, the ST-251 was slow and very noisy, but it tended to keep on going for a good while — unlike some of its over-stressed RLL relatives, which were even worse than the Miniscribe drives.

There were several versions of this long-lived drive: the 28ms ST-251-1 was much faster than the standard model (ST-251-0 or plain ST-251), and then there was the ST-277R, which was a tweaked-up RLL variant. The 277R was, not to put too fine a point on things, a dud to be ranked alongside the notorious Kalok Octagon and the dreadful Samsung SHD-125. Reliability problems with the ST-251 variants cast a pall over the entire company for some years afterwards, which was a shame as both the sluggish ST-251-0 and the surprisingly speedy ST-251-1 were solid, reliable performers.

The ST-251 made a unique hollow knocking noise on start-up, once heard never forgotten, by far the most distinctive sound of any drive yet made. Performance figures are for the ST-251-1.

Data rate5 Mbit/secSpin rate3600 RPM
Seek time28ms (or 40) ActuatorStepper
Platter capacity14.3MBInterfaceMFM
AT drive type40 or 44Form5.25" half-height
ST-251-142.8MB6 thin-film heads

Note: ST-251 is the correct term. Many references are made elsewhere to the "Seagate ST251", these are in error. See the note at the bottom of the ST-225 entry for details.