[ INDIVIDUAL COMPONENT // HARD DISK DRIVES ]
Seagate ST-4096
80 MB 5.25-inch full-height MFM drive with a 9-head CHS geometry. This entry describes the named model, not every drive with similar markings.
IDENTIFICATION: Record the complete label, suffix, revision and controller details before handling. Do not substitute a related model’s geometry or encoding based on appearance alone.
Model specifications
| Exact model | Seagate ST-4096 |
|---|---|
| Catalog classification | MFM and early magnetic drives |
| Capacity | 80 MB formatted (96 MB unformatted, per OEM documentation) |
| Form factor | 5.25-inch full-height (FH) |
| Interface | ST-412-compatible, separate control/data cabling |
| Recording method | MFM; do not infer encoding/controller compatibility from the connector alone |
| Drive geometry | 1024 cylinders × 9 heads × 17 sectors/track; 512-byte sectors |
| Host-controller compatibility | Requires an ST-506/ST-412 MFM controller that supports the drive’s 9-head geometry, capacity and low-level format, with compatible BIOS/driver translation where needed. Verify cabling, drive select and termination from the OEM manual. |
| Historical caveat | An 80 MB MFM drive’s CHS geometry can exceed the fixed type tables of some early PC BIOSes. A supported controller BIOS or operating-system driver may be required; a connector match is not a compatibility guarantee. |
Host-controller compatibility
Requires an ST-506/ST-412 MFM controller that supports the drive’s 9-head geometry, capacity and low-level format, with compatible BIOS/driver translation where needed. Verify cabling, drive select and termination from the OEM manual.
- Confirm the full model and revision on the label, controller make/model, cable pinouts, power requirements, drive-select jumpers, and termination before connection.
- Verify that the controller supports the exact encoding, CHS geometry and sector size shown above; controller and BIOS translations can vary between systems.
- Do not attach this drive directly to modern SATA, IDE/ATA, SCSI or USB ports. Any bridge must explicitly support the legacy ST-506/ST-412 signaling and drive format; connector resemblance is not electrical compatibility.
Historical and preservation notes
The ST-4096 is a distinct high-capacity MFM model, not an IDE, ESDI or SCSI drive. The OEM manual’s unformatted and formatted figures are different capacity measures and should not be conflated.
These drives are decades old. If data matters, avoid exploratory low-level formatting, repeated power cycling or writes; preserve the original controller settings and seek qualified recovery help for a failing mechanism. Treat any catalog capacity as approximate until the original manual and host configuration are checked.
Sources & further reading
- Seagate ST-4096 OEM Manual (archival scan)OEM manual with model-specific specifications and installation information.
- Seagate ST-4096 configuration and geometry referenceIndependent model listing for form factor, MFM interface and geometry; the OEM manual takes precedence.
Use the model-specific documentation for the full label and revision. Third-party archival listings are useful cross-references but may summarize a family or use rounded capacity values.