A dead ST-251

What I tried

Identified the 5271’s controller from the silkscreen: Western Digital WD1002A-WX1, assembly 60-600003-02, BIOS ROM 62-000094-030, the Super BIOS. Ran the on-card formatter from DEBUG with G=C800:5. Tried SpeedStor 6.0.3 too, but DEBUG against the card’s own formatter worked best. Swapped drives, cables and cards in and out for a while.

What I measured

The first format completed and reported 612 cylinders and 4 heads, about 21 MB. The ST-251 is 820 cylinders, 6 heads, 17 sectors, about 40 MB. That’s the card’s fixed mode: geometry comes from a drive table selected by the S1 jumpers, and the table stops at 663 cylinders.

In dynamic mode with the right geometry the format ran for hours and never finished. The drive swept full stroke about once a second the whole time.

What broke or surprised me

The drive was dead. The same process worked fine on two other ST-251s. Of the four, two are good.

Also, SpeedStor’s MediaAnalysis scans cylinder 0 head 0, which is where the WD card keeps its dynamic geometry, and wipes it.

Next

Floppies before hard drives. The 5271’s floppy had started acting up.