Overview

You will also need a pin crimper that fits AWG28 wires/pins like a good old Radio Shack 276-1595, or generic "SN-28B" sold by several different manufacurers, just pick any. They can be less than $15 on ebay

Pinouts

+------------------------------------------------+
|                                                |
|                                                |
|                 RS-232C                        |
|                   ___                          |
|               +--+   +--+              +-----+ |     
|               | 7 5 3 1 |              | (o) | |
|               | 8 6 4 2 |              |     | |
|               +---------+              +-----+ |
+------------------------------------------------+

1 GND

2 CTS

3 DTR

4 RTS

5 DSR

6 TXD

7 RXD

8 NC

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. Note that most generic "Dupont" connetcor housings put the pin-1 marker in a different corner than IDC plugs do (on what we're calling pin 7). So, if you use a regular non-polarized "Dupont" connector housing, You'll have to ignore it's pin-1 marker. That's the great thing about standards, you have so many of them to choose from. ;) The connector housing in the DigiKey order above has a pin-1 marker in the correct place, or might have no mark at all (see drawing).

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 arrangement 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.)

Another Option for a cable

Rick Shear has taken a new and very careful look at a real cable and the Marty Goodman doc, and has probably identified the components that Marty Goodman didn't. This is probably the most electrically accurate cable.

https://rsmicro.wordpress.com/2018/08/26/tpdd-cable/

https://rsmicro.wordpress.com/2018/09/08/built-tpdd-cable-comparison-to-oem/

https://oshpark.com/shared_projects/vntX40yC

http://www.digikey.com/short/j20td4

UPDATE: I have now built one of Rick's cables, and it works. A couple of further details and errata...

The db25 hood in the digikey order above is not a great choice. It's somewhat larger most, and doesn't come close to fitting in a Model 100. It's usable witha Model 102 or 200. I selected it originally because it has a selection of strain relief grommets that go down small enough to grip the small cable tightly. But, on the other clhand, I don't know of any db25 hood that fits in the Model 100 serial port opening. Factory molded plugs barely fit.

It is quite a pain in the neck crimping the tiny individual dupont connector pins. It takes 3 hands. One to hold the pin in position in the crimper, one to hold the wire in position in the pin, one to crimp! By being very careful, it's possible to just barely start crimping the pin, just enough for the crimper to hold the pin without closing it yet, then you can let go of the pin and use that hand to position the wire and finish the crimp. That's one pin. only 6 more to go!

There is a kit of assorted double-walled heat-shrink from NTE. HS-ASST-13 It was ideal for this for a few reasons. The "double wall" actually seems like the inner wall is more like hot-glue. It closes up and flows to fill in the interior and grabs on to the wire and the dupont connector very securely. One of the included sizes is good for the wire on the db25 end. Another of the included sizes is big enough to go around the outside of the dupont connectore, yet still shrinks down far enough to grab the much smaller serial cable. That is remarkable. (The box does say shrink ratio 3:1) The inner glue-like wall glues itself to the dupont connector well, which provides much needed strain-relief for the delicate idividual wires. The heat shrink is very thick and forms a solid hard object that is safe to grab like a factory molded plug. The polatlrity bump on this dupont connector, plus the thick heat shrink around the outside, makes the combined finished plug just big enough so that the polarity bump actually works andnprevents you from plugging in the plug the wrong way.

This particular dupont connector does not have any pin 1 mark ( which is fine, because the header in the TPDD is numbered like an IDC header, while most dupont connectors are not. Most dupont connectors would have a pin 1 mark where the TPDD has pin 7. A femal 2x4 IDC plug would have a pin 1 mark in the right spot, top-right corner, looking at the back of the tpdd.)

The numbers 1 to 8 on the silk-screen on the pcb DO correspond to the numbers in the diagram above, and the Marty Goodman doc. So that is how you can tell which pin on the pcb is supposed to go to which position on the dupont connector. Just match up the numbers from the pcb with the diagram above.

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

TPDD

Contents

Overview

Common features of both versions

Tandy Portable Disk Drive

Tandy Portable Disk Drive 2

Parts

Belt

Cable

Another Option for a cable

Software

For PCs

For M100/102/200

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