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

Batteris: 4 x AA

Wall power: 5.5mm x 2.1mm, 6vdc, center negative, 400ma (Tandy 26-3804)

Media: 3.5" DD, aka "720K" diskettes (not HD 1.44M)

Drive is single-sided. The disks may be single or double-sided, but the drive only uses one side.

Tandy Portable Disk Drive

100K

TPDD bootstrap procedure

TPDD Operation Manual

Command Reference

Software Manual

Tandy Portable Disk Drive 2

200K in the form of 2 100K banks (still only uses one side of the disk)

TPDD-2 bootstrap procedure

TPDD-2 Operation Manual

Parts

Belt

Standard size code: FRW-8.5

Search google or ebay for: "FRW-8.5 belt"

Cable

M100SIG/Lib-09-PERIFERALS/TPDD.DO

Parts to build one cable

You will also need a awg28 pin crimper like this https://www.amazon.com/IWISS-Terminal-Ratchet-AWG28-18-0-1-1-0MM%C2%B2/dp/B017JU20Z6

Pinouts... (until I make a diagram)

For the TPDD end of the cabel, the pin numbers used by Marty Goodman conform to the numbering on a standard IDC connector, female, 2x4, with polarity bump. (That kind of connector doesn't actually fit in the TPDD/TPDD-2, but the pinout is the same). Looking at the back of the TPDD: top-right pin is 1, bottom-right is 2, top-left is 7, bottom-left is 8.

For the computer end, any rs232 reference shows the pinout, if you only look at the signal names and pin numbers, but ignore the physical location in most diagrams. Most diagrams will show the arrangeement when the computer has a male plug, while the M100 has a female. But the pin numbers are correct, and you can read the pin numbers right on the db25 connector and ignore any drawings to find where pin #N actually is on the plug.)

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