HP 82901M 5.25in 270K FDD
| General Info | |
|---|---|
| Release Year | 1980 |
| Manufacturer | HP |
| Condition | Working |
| Identifiers | |
| Model Number | 82901M |
This is a dual 5.25" floppy drive for HP systems from the late 1970s and early 1980s.. It's HP-IB interface and Amigo protocol makes it compatible with a large number of HP computers, for example the HP 9836C Technical Computer & HP 85.
Floppy Disk Drives
The internal floppy drives are standard Shugart interface compatible drives, the example I have used Tandon TM200-2A drives. As such a drive emulator like a Gotek can be used in place of them.
The left drive has DS0 set and the right DS1 as described in the Tandon Manual[1]. A Termination pack is also installed in the drive at the end of the shared cable in U2F.
Disk Structure
Double Density 5.25" disks used in the system are formatted with a LIF filesystem using 33 tracks, 16 sectors per track, and 256 bytes per sector for a total capacity of approximately 270KiB. The LIF filesystem measures usage in blocks, these disks have a total block size of 1056.
To decode flux data from a raw image of a LIF 5.25" disk, you can use the following Greaseweazle (archived) diskdef to properly decode it
disk hp.lif.40dd
cyls = 33
heads = 2
tracks * ibm.mfm
id = 0
interleave = 1
secs = 16
bps = 256
end
end
Note that sector's are 0 indexed requiring id = 0
Repairs - Modifications
2023-06
- Large power supply capacitors reformed
- Standoffs for right drive repaired with epoxy after damaged in shipping
- Bearings for disk spin hub/flywheel re-lubricated after being seized
- FAIL - Discovered right floppy drive top head is bad, replacement needed
2023-07
- Replaced right floppy drive with Tandon TM100-2A unit from IBM
- Note: Replacement drive was manually calibrated for track alignment after having unrelated issues.
External Projects and Software
- HPDir (archived): LIF filesystem browser and tools
- lifutils (archived): LIF filesystem browser and tools
Related Devices
External links
- ↑ Page 26 of "OEM OPERATING AND SERVICE MANUAL TMIOO-l, TMIOO-2 DISK DRIVES 48 TRACKS PER INCH" in the Tandon Manual (archived)