Revision as of 04:24, 7 June 2019

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 a set of 3 of these cables, and they work great.

Pictures

A couple of further details and errata...

The db25 hood in the digikey order above doesn't fit in a Model 100. Remove that part from the digikey order and get this one instead:

https://www.mouser.com/ProductDetail/HARTING/09670250411?qs=sGAEpiMZZMu5A18b%252BIx2GqJxiHQ0oido1QO%2FNnySBX8=

It is quite a pain in the neck crimping the tiny individual dupont connector pins.

The numbers 1 to 8 on the silk-screen on the pcb DO correspond to the numbers on the TPDD connector 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 silkscreen with the positions in the diagram above. One of the pictures in the google photos album above also shows both connectors side by side with all wires connected and all colors and all positions visible, so you can also use that picture to just look at the colors of the wires on both sides.

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

@@ Line 78: / Line 78: @@
 :A couple of further details and errata...
-* The db25 hood in the digikey order above is not a great choice. They don't fit in a Model 100. Remove that part from the digikey order and instead do one of the following:
+* The db25 hood in the digikey order above doesn't fit in a Model 100. Remove that part from the digikey order and get this one instead:
-:: Mouser has a hood that would fit. Though I don't know if this PCB fits inside that hood.
+https://www.mouser.com/ProductDetail/HARTING/09670250411?qs=sGAEpiMZZMu5A18b%252BIx2GqJxiHQ0oido1QO%2FNnySBX8=
-:: https://www.mouser.com/ProductDetail/HARTING/09670250411?qs=sGAEpiMZZMu5A18b%252BIx2GqJxiHQ0oido1QO%2FNnySBX8=
-: or
-:: Modify a common hood to fit:
-:: Remove the front lips that hold the metal connector in the plastic shells. Score the inside with a knife and will break off clean and flush with the rest of the face of the shell. Now the plug will fit in a Model 100, but nothing is holding the connector to the shell.
-:: Remove the 2 strain relief/retaining screws from the sides of the connector, but keep the bent rectangular washers.
-:: Install 4-40 x 3/4" screws and nuts in the screw holes, with the heads of the screws on the connector face, and the nuts and rectanglar washers on the back where the original screw heads were. Now the connector is bolted to the shell, and the screws and nuts are doing the job that the plastic lips used to do.
 * It is quite a pain in the neck crimping the tiny individual dupont connector pins.
-A better idea would be to just solder a 2x4 female header to the edge of a tiny pcb with the 3 components on it, and solder a plain serial cable to that, with one end cut off and soldered to the pcb and the other end with a factory molded db25 plug. That would eliminate the need to crimp dupont pins (and buy the special pin crimper tool), and elimitate the problem of the db25 hood fitting in the small opening in a Model 100.
+* The numbers 1 to 8 on the silk-screen on the pcb DO correspond to the numbers on the TPDD connector 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 silkscreen with the positions in the diagram above. One of the pictures in the google photos album above also shows both connectors side by side with all wires connected and all colors and all positions visible, so you can also use that picture to just look at the colors of the wires on both sides.
-* This heat shrink kit, NTE HS-ASST-13, was *great* for this. It says double wall, but actually seems like the inner wall is more like hot-glue. The inner wall is almost clear and flows to fill in irregular shapes on 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 connector, and the 3:1 shrink ratio means it shrinks down far enough to grab the much smaller serial cable. That is remarkable. The inner glue-like stuff 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, and holds the dupont connector and the end of the serial cable rigid so the small wires don't flex at the dupont connector. The polarity 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, and prevents you from plugging the cable in the wrong way.
-* The numbers 1 to 8 on the silk-screen on the pcb DO correspond to the numbers on the TPDD connector 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 silkscreen with the positions in the diagram above. One of the pictures in the google photos album above also shows both connectors next to each other with all wires connected and all colors and all positions visible side by side in the same picture, so you can also use that picture to just look at the colors of the wires on both sies.
 =Software=

TPDD: Difference between revisions

Revision as of 04:24, 7 June 2019

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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