TPDD
Overview
There were two versions of the Tandy Portable Disk Drive. Both were very similar. The drive is a a re-branded Brother FB-100.
Common features of both versions
- Size, shape, weight
- 4xAA Batteries
- 5.0mm x 2.1mm, 6vdc, center negative, 400ma, wall power (IE: Tandy 26-3804)
- 3.5" DD disks (aka "720K", not 1.44M HD disks).
- Single-sided drive. The disks may be double-sided, but the drive only uses one side of the disk.
Tandy Portable Disk Drive
- 100K
- dip switches to set rs232 parameters
- longer bootstrap procedure
Tandy Portable Disk Drive 2
- 200K in the form of 2 100K banks (still only uses one side of the disk)
- fixed rs232 parameters
- shorter bootstrap procedure (link to tpdd-2 boot procedure)
Documents
https://archive.org/details/Portable_Disk_Drive_Command_Reference_19xx_Tandy
Parts
Belt
Search goole or ebay for: "FRW-8.5 belt"
Cable
The real cable has some active components. (TODO, link to schematic of original cable) It's thought that today you could just use a cable like below, using schottke diodes specifically, and it's probably equally as good as the original cable which had transistors.
Simpler Cable that is claimed to work.
Software
For PCs
TPDD used a double density 3.5" floppy, aka "720K" disk, but used a format that is incompatible with modern pc drive controllers. Normal MS-DOS formatted disks are written with MFM encoding, while the TPDD used FM encoding. Event using special software to read non-standard formats, you can't make a normal drive & drive controller read or write FM.
To read or write a TPDD disk from a modern machine, you need a working TPDD drive and the special RS232-to-TTL serial cable that came with it, and a "TPDD Client" software to talk to the drive over the serial connection the same way the M100 does.
There are several TPDD clients for more modern machines. Most of these are themselves also now no longer modern. For example Lap-Desk and PDD are both 16-bit DOS programs that don't work on Windows.
TpddTool Python TPDD Client
For M100/102/200
The normal way to use a TPDD is to install a "dos" on an M100. Several such dos's have been made. The drive came with a utility disk and a functional dos called "floppy". Others have been made by 3rd parties that provided more features or smaller ram footprint or more fleible installation/usage. There are also various special purpose utility programs aside from dos's.
Floppy/Floppy2
teeny
ts-dos