zaphod@madnix.UUCP (Ron Bean) (12/09/89)
In Article <1989Nov29.035428.26053@athena.mit.edu>, gordo@athena.mit.edu (Garet G Nenninger) writes: >Does anyone know the format of the serial data which is sent to the >Tandy Portable Disk Drive (PDD) for the Model 100? Also, what is the >arrangement of signals on the connector? > >I have a Cambridge Z88 laptop, which several companies make disk >drives for. However, the two I've read about are both PDDs with new >connectors and some driver software in BASIC with machine code. For >the price that they charge, I'd rather write my own code. If anyone out there has a Model 100 and a PDD and would like to give it a try, it's apparently not that hard to figure out. A few years ago a student here patched the software so it would spy on the serial port while he saved & loaded test files to the drive; he said the commands were in one format and the replies in another (one used BCD and the other used hexidecimal characters). I don't know the details. Radio Shack has the M100 on sale again, but I don't know if it's cheap enough to buy one just to experiment on. Note that the PDD only stores about 200K on a disk. The connector is "standard" RS232. When I had an account on Compuserve, the M100SIG had some utility programs for the PDD, but they may have depended on Radio Shack's driver software. They also have files that describe the M100's ROM routines. The interrupt vector for the UART is stored at $F5FC (normally points to $6DAC), the routine at $6E32 sends the character in the A register to the UART, $6D7E gets a character from the UART (or waits for one), and $6D6D returns the number of characters in the input buffer (in the A register). You'll need a disassembler to work out the details. Another possibility would be to put another computer between the M100 and the PDD and use that to spy on the signals going back and forth. BTW, I played with a Z88 a while back; the rubber keyboard is a little wierd, but I actually liked it. I also played with Radio Shack's WP-2, and noticed that it shares one problem with the Model 100: response is OK if you're editing a short file, but very slow if you're editing a long one. ================== zaphod@madnix.UUCP (Ron Bean) {harvard|rutgers|ucbvax}!uwvax!astroatc!nicmad!madnix!zaphod {decvax|att}!