TRS-80 Model 4 help requested

From: Don Maslin <donm_at_cts.com>
Date: Fri Feb 28 23:39:00 2003

On Fri, 28 Feb 2003, Tony Duell wrote:

> > On Thu, 27 Feb 2003, Tony Duell wrote:
> >
> > > > Aparently, the Drive 0: is bad. Replacing it with the 1: or an
> > >
> > > Does the spindle motor run on this drive when you try to boot from it?
> > > Does the LED come on?
> >
> > Sorry, guess I should have been more specific. The (drive that was
> > 0:) drive spins, and the LED comes on, but the machine still says "Cass?".
>
> OK...
>
> What test equipment do you have available? Multimeter? Logic probe? Logic
> analyser? 'scope?
>
> I can probably suggest signals to look at to find out exactly what's
> going on...
>
> > The other drive (which I had replaced it with) attempts to read from the
> > disk, and either displays "Diskette?" or nothing if there's no disk in the
> > drive or a disk, respectively.
>
> Of course at this point you don't _know_ that the disk controller or CPU
> boards are working correctly...
>
> >
> > > > IBM-branded Tandon drive from an IBM 5150 PC, it seems to try to boot from
> > >
> > > What have you done about the termination resistor pack (the 'odd coloured
> > > IC' on the drive logic board)? The machine will not do the right things
> > > if the last drive on the cable is not terminated.
> >
> > Maybe this is part of the problem. Neither drive has a terminator on it.
>
> Are you sure? It normally goes in a DIL socket near the interface cable.
> Is there a totally empty socket on both drives?
>
> > What resistance is it? I could probably try making one out of spare
>
> 150 Ohms, but I can't remember if the resistors are separate or if they
> have a common connection to the highest-numbered pin on the package. I
> think the former.

They are separate resistors without interconnection.

                                                        - don

> > > > 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?
> > >
> > > I've not written one yet (although it would not be hard to do). However,
> > > I belevie xtrs can do this (BACKUP from a physical disk to an emulated
> > > one). Since I don't run X, I can't be sure, though.
> >
> > I haven't seen anything in xtrs that lets me use a physical disk, only
> > disk images. Does anyone know if I'm mistaken and xtrs will read disks?
>
> I have the source of an old version on this machine. I can't run it,
> because I don't run X, of course, but a quick grep shows a number of
> FDRAWCMD ioctl()s in trs_disk.c. Which implies to me that it's accessing
> the PC disk controller at a low level, to read a non-native (for the PC)
> disk format, presumably a real TRS-80 disk.
>
> -tony
Received on Fri Feb 28 2003 - 23:39:00 GMT