Ok, I've taken the time to take it apart and try a few things, still no
luck...
I wrote:
> I recently picked up a TRS-80 model 4, that seems
to have problems with
> its floppy drives.
>
> The machine is a base Model 4 with 64KB of ram (I think - haven't yet
> taken the EMF shield off the mainboard), and no peripherals attached.
> When I powered it up the first time, with or without a disk in the
> (bottom) drive, it displayed "Cass?" on the screen, and then I could
press
> enter to that and the "Memory size?" prompt, and get a basic prompt.
On Wed, 26 Feb 2003, Tony Duell wrote:
I beleive that means it can't find a disk
controller, so it assumes you
have a cassette-only system.
Try re-seating the 'ribbon cable' between the CPU board and the disk
controller PCB _at both ends_. I would estimate that over 50% or disk
problems on M3s and M4s come from this cable!
Aparently, the Drive 0: is bad. Replacing it with the 1: or an
IBM-branded Tandon drive from an IBM 5150 PC, it seems to try to boot from
the disk. No disk in the drive (or the disk upside down) yields a
"Diskette?" message on the display. A disk placed right-side up, which
should be bootable, gives no messages on the display after power-up or
reset. However, with a disk inserted, the drive light (and motor) turn
off after approx 7 seconds.
I tried using a boot disk that I got with the machine, and a fresh one
from a .dsk file of LS-DOS 6.3.1H from Tim Mann's
web site, using Tony's
trsfmt and diskdmp. The image works with xtrs too, so
I'm fairly
confident that it should work when stuck on a floppy.
Also, the disk
I used was supposed to be a TRS-DOS (bootable) disk, but
it's possible that they've gone bad after so many years. Are the disks on
the Model 4 recorded so that I can read them on a PC (IE 48/96tpi MFM,
compatible with the NEC D765)? I'd like to know if I can make backup
images and/or see if the disks work on another machine.
Mostly. It is standard MFM encoding (well, the TRS-80 can do FM (single
density) too, but the M3 and M4 at least expect the boot sector to be
double desnisty, and the standard OSes use double density (MFM) encoding
for the entire disk.
I would like to try to make an image from the disks I have, is there a
program that works under Linux with a standard floppy disk controller to
read disks and spit out .dsk files?
Pat
--
Purdue Universtiy ITAP/RCS
Information Technology at Purdue
Research Computing and Storage
http://www-rcd.cc.purdue.edu