[ INDIVIDUAL COMPONENT // HARD DISK DRIVES ]
Seagate ST-251
5.25-inch half-height MFM hard disk, 1980s. This record describes this exact catalog identity; related capacities, interface variants, suffixes, and revisions may have different properties.
IDENTIFICATION: Compare the complete model and suffix on the label with the manufacturer document and actual drive inquiry. Family-level values do not describe every revision or the condition of a particular unit.
Part specifications
| Catalog subcategory | MFM and early magnetic drives |
|---|---|
| Catalog identity | Seagate ST-251 |
| Product family | 5.25-inch half-height MFM hard disk, 1980s |
| Form factor | 5.25-inch half-height; exact external dimensions are not inferred from this class. |
| Interface | ST-506/ST-412-compatible MFM interface; requires a compatible controller and separate data/control cabling. |
| Capacity / performance / sectors | 40 MB formatted nominal capacity; model manual lists 820 cylinders and 6 heads. Controller geometry and formatting affect usable volume. |
| Compatibility | Use the ST-251-specific geometry, controller support, and manual settings; MFM cabling and controller are not interchangeable with IDE/SATA. |
Handling, service & preservation
- Do not apply power until the controller, cabling, drive select, termination, and power connections are checked. Record original jumper/configuration positions before service.
- Before service, photograph the label, connectors, board markings, firmware/model identity, and installed carrier; note condition and any prior repair.
- Never open a hard disk outside a qualified clean environment. Mechanical shocks, contamination, and uncontrolled power cycling can worsen failure.
- For preservation, make independent verified copies and record checksums and read errors; SMART or self-test results are useful evidence but do not guarantee future reliability.
Model-specific source
- Seagate ST-251/ST-251R/ST-277R Product Manual, document 36035-001 Rev. A (1987; scan)Original Seagate product manual scan; source includes ST-251 and its separately identified RLL siblings. Verify this unit is the ST-251, not ST-251R or ST-277R.
Values above are limited to the cited exact-model or clearly identified model-family document. Record the document revision with any collection measurements.