TPDD: Difference between revisions
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Revision as of 23:06, 9 June 2020
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
Tandy Portable Disk Drive 2
200K in the form of 2 100K banks (still only uses one side of the disk)
Parts
Belt
Standard size code: FRW-8.5
Search "FRW 8.5 belt" on Google or ebay
Cable
The "RS-232" interface to the TPDD is actually 0v to -5v TTL, while rs232 serial ports use -12v to +12v. So the cable isn't just a cable, it has electronics to convert the signal levels between TTL and RS232.
Pinout
+------------------------------------------------+ | | | | | 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
- Assembly:
- Solder all components to pcb per the render pics.
- Cut the db9 plug off the serial cable. Strip the outer sheath back 1 to 2 inches. Strip each wire 1/8".
- Put 2 to 3 inches of 1/2" diameter heat shrink on the serial cable. (don't shrink yet)
- Identify which color wires go to which pins on the DB25 plug.
- Find pin 2 on the db25
- Find which color wire goes to pin 2 using a DMM continuity tester
- Repeat for all the numbered holes on the PCB: 2,3,4,5,6,7,20
- Cut any left-over wires short right at the cable sheath.
- Solder the wires to their matching numbered holes.
- Secure the end of the cable to the pcb with a zip-tie. Even better, put some glue on the pcb before pressing the cable in place
- Add some hot-glue around the soldered wires where they meet the pcb.
- Pull the two un-soldered pins out of the female 2x3 pin socket.
- Slide the heat-shrink up over the pcb and shrink.
Software
For PCs
TPDD used double density 3.5" disks, 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. Even 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 level-shifting 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 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
There are several TPDD_servers, which are programs that run on a host pc, that don't *use* a TPDD, but they emulate *being* a TPDD, so a Model 100, 102, 200, WP-2, NEC PC-8201, PC-8201a, PC-8300, Kyotronic KC-85, Olivetti M-10, can save and retieve files on a modern computer.
For M100/102/200
The normal way to use a TPDD is to install a "dos" or TPDD_client 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 flexible installation/usage. There are also various special purpose utility programs aside from dos's.