Tandon TM100-1
The Tandon TM100-1 is a full-height 5.25" single-sided double-density (SS DD) floppy disk drive, 48 tracks-per-inch (TPI), 40 tracks per side, supplied as the original drive in the first batch of IBM PC (5150)s and as the standard drive in some Apple II and S-100 systems of the same era. It stores 160 KB per disk under PC DOS 1.0 (180 KB under PC DOS 2.0+).
Specifications
- Form factor: 5.25" full-height (1.6").
- Heads: 1 (single-sided).
- Tracks per inch: 48.
- Tracks per side: 40.
- Encoding: MFM, 250 kbit/s.
- Unformatted capacity: 250 KB.
- Formatted capacity: 160 KB (PC DOS 1.0, 8 sectors/track) or 180 KB (PC DOS 2.0+, 9 sectors/track).
- Stepper motor: four-phase, 6 ms step time.
The TM100-1 has the same mechanics as the double-sided Tandon TM100-2 but only one read/write head. Visually the drives are nearly identical; the TM100-1 is identified by its single-head carriage and by the part-number label on the rear.
Common Faults
- Drive belt failure — the rubber belt between the spindle motor and the spindle hub stretches or breaks. Replacement belts are inexpensive and the drive cannot be operated without one.
- Stepper grease drag — the head-positioner lead screw is lubricated with grease that hardens over decades, preventing the heads from stepping cleanly. Clean with isopropyl alcohol; re-lubricate with white lithium grease.
- Dirty heads — the single head needs cleaning with a foam swab and isopropyl alcohol every few hundred disk reads in regular use.
- Track 0 sensor failure — the optical sensor that detects track 0 gets dusty; clean with isopropyl alcohol.
Disk Compatibility
A TM100-1 can read single-sided disks written by any other 48-TPI MFM 40-track drive. It cannot read double-sided disks at all (it has no second head), and it cannot read 96-TPI 80-track disks (the head and stepper increment are different).
Related Pages
- IBM PC (5150)
- Tandon TM100-2 — the double-sided successor
- IBM FDD Adapter — the controller card