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.
| Performance | 0.23 | Reliability | AA2 |
| Data rate | 5 Mbit/sec | Spin rate | 3600 RPM |
| Seek time | 28ms (or 40) | Actuator | Stepper |
| Platter capacity | 14.3MB | Interface | MFM |
| AT drive type | 40 or 44 | Form | 5.25" half-height |
| ST-251-1 | 42.8MB | 6 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.