[ INDIVIDUAL COMPONENT // HARD DISK DRIVES ]
Seagate ST-238R
33 MB-class 5.25-inch half-height RLL drive; ST-412-compatible wiring with RLL encoding. 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-238R |
|---|---|
| Catalog classification | MFM and early magnetic drives |
| Capacity | 33 MB formatted (often rounded to 30 MB in contemporary class descriptions) |
| Form factor | 5.25-inch half-height (HH) |
| Interface | ST-412-compatible, separate control and data cables |
| Recording method | RLL 2,7 (Run Length Limited); model suffix R identifies the RLL-qualified variant |
| Drive geometry | 615 cylinders × 4 heads × 26 sectors/track; 512-byte sectors per the model listing |
| Host-controller compatibility | Use a compatible RLL 2,7 controller configured for this model’s 615/4/26 geometry. Similar cabling does not make MFM and RLL controller operation equivalent; configure drive select and termination per the actual host card and manual. |
| Historical caveat | The ST-238R is distinct from the MFM ST-238. RLL capacity is not a universal upgrade path: unqualified MFM mechanisms/controllers can yield read/write errors or data loss when run at the denser encoding. |
Host-controller compatibility
Use a compatible RLL 2,7 controller configured for this model’s 615/4/26 geometry. Similar cabling does not make MFM and RLL controller operation equivalent; configure drive select and termination per the actual host card and 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
ST-506/ST-412 legacy systems have no universal autoconfiguration. BIOS geometry, controller BIOS limits, interleave and low-level formatting determine whether the advertised geometry is usable by a particular host.
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
- ST-238R model specifications and jumper notesModel-specific geometry, interface and configuration reference; verify its values against the unit documentation.
- Seagate ST-412 OEM Manual (archival scan)Primary family/interface reference for compatible cabling and installation; use the ST-238R model record for its RLL geometry.
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.