[ INDIVIDUAL COMPONENT // HARD DISK DRIVES ]
Tandon TM262R
20 MB-class 3.5-inch half-height RLL drive; distinct from the MFM TM262. 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 | Tandon TM262R |
|---|---|
| Catalog classification | MFM and early magnetic drives |
| Capacity | Approximately 20 MB formatted (model listings vary in rounding) |
| Form factor | 3.5-inch half-height (HH) |
| Interface | ST-506-compatible cabling with RLL encoding; 34-pin control and 20-pin data |
| Recording method | RLL 2,7 |
| Drive geometry | 782 cylinders × 2 heads × 26 sectors/track; 512-byte sectors in the model setup |
| Host-controller compatibility | Requires a compatible RLL 2,7 ST-506 controller set for the TM262R geometry and correct drive-select/termination configuration. Do not connect as an MFM TM262 solely because the cable interface is similar. |
| Historical caveat | The R suffix is significant: TM262R is an RLL model, whereas TM262 is an MFM model with a different CHS setup. RLL operation can be unreliable on an MFM-only controller or a mechanism not qualified for RLL. |
Host-controller compatibility
Requires a compatible RLL 2,7 ST-506 controller set for the TM262R geometry and correct drive-select/termination configuration. Do not connect as an MFM TM262 solely because the cable interface is similar.
- 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-506 physical interface describes cabling/signals, not the recording encoding. Confirm both the encoding and controller support; preserve the complete drive label and jumpers as part of any restoration record.
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
- Tandon TM262R model geometry and setupModel-specific RLL interface, form-factor and configuration reference.
- Tandon TM362/TM262 Product Specification and User Manual (archival scan)Archival manual for related TM262/TM362 family context; use it alongside the exact TM262R model reference, not in place of it.
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.