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Getting a TRS-80 Model 4 back on its feet

B

bitfixer

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San Francisco, CA
Hi,

I made a recent lucky find of a TRS-80 Model 4. I happened to mention my interest in old computers to a local shopkeeper and he mentioned that he had a TRS-80 in his garage.. so now it has a new home.
This is my first go-around with a TRS-80 so I'm learning as I go. When switched on, the bottom drive lights up and spins, and "Diskette?" appears on the screen. I'm assuming this is normal behavior.
Using Dave Dunfield's Imagedisk program, I created a floppy of a Model 4 startup disk, which is supposed to have TRS-DOS and a basic interpreter. I used a 386 machine to create the image, with a 5.25" HD drive. This same drive was used to create Kaypro II CP/M disks with success, and I have added a jumper to make it run at 300rpm as opposed to 360rpm.

After creating the disk, I attempted to boot the TRS-80 with it. When the machine is turned on with the disk in, "Disk Error" appears at the center of the screen after a few moments. I also tried to boot from another disk I created, whose image was described as a TRS-DOS upgrade. When attempting to boot from this one, it says "Cannot Boot, DATA DISK". So the drive is reading something differently between the two disks.

Just wondering if anyone had a suggestion for the next step in getting this machine running again. I can try making a floppy with a real DSDD drive to see if that makes a difference. I'm thinking there could also be an issue with the drive on the TRS-80, so perhaps switching the top and bottom drives could work? Or trying it with a known working drive would be a possibility, but I'm not sure what types of drives will work with this machine.

Any advice welcome, thanks!
- Mike
 
Try degaussing the DS2D floppy before formatting it with the HD drive. Or use brand-new unformatted media--or just use the 360K drive out of the Model 4.
 
Thanks,

I tried degaussing the floppies with a bulk eraser for magnetic tape, but the result was the same. Next time I can I'll try imaging the disk with the drive from the Model 4 itself.
The Model 4's drive seems to be quite loud when spinning, which makes me wonder if there's a bearing or some type of mechanical part that needs adjusting.
 
Mike,

If you still have problems after following Chuck's advice, you could try one of the two TRS-80 emulators to create disk images as outlined here.

If you don't have a DS DD drive, then wiring up the TRS80 one to the PC is good thing to do. At least that takes one complicating factor out of the equation. I haven't explored my own Model IV drives but if they are like the Model III one's I've come into contact with, the issue is complicated by the fact that drives are selected via missing pins in the cable. This doesn't mean to say they won't work with the PC, there just may be jumpers to set etc.

Tez
 
Thanks Tez, Chuck. Sounds like I have a few things to try to get this guy back on his feet.
This machine will be living at my parents' place for a while, since I found it while visiting for the holidays. It would be a bit hefty to bring back on the plane :) So I'll have to wait until next visit to work on it again. Looking forward to trying these ideas out when that happens.
 
One other thing. In making a real boot disk with one of the emulators you can then at least test it in the PC (while running an emulator) to see if you get a good boot. Then at least that narrows the problem to a possible drive issue rather than the imaging software.

If you get a good boot, it's likely the disk is good (assuming the drive it was imaged on is aligned correctly and so the disk is transferrable to other drives.)

Tez
 
If all else fails, I'm happy to send you a known good boot disk. There might be those closer than me that can do this but the offer still stands.

I'm still enjoying your PetDisk.

Cheers

Tez
 
Chuck(G) said:
Try degaussing the DS2D floppy before formatting it with the HD drive. Or use brand-new unformatted media--or just use the 360K drive out of the Model 4.
Click to expand...

Unless it's a 4D, I believe that the drives are SSDD, so, it would only be a 180K diskette.

If you go to http://www.trs-80.com you'll find a spot where you can request actual DOS disks of varying types. You can make an optional donation, if you like, but, either way, you'll end up with more than you asked for.
 
Druid6900 said:
If you go to http://www.trs-80.com you'll find a spot where you can request actual DOS disks of varying types. You can make an optional donation, if you like, but, either way, you'll end up with more than you asked for.
Click to expand...

Ira hooked me up with the latest patched L-DOS and a nice stack of other progs for my 4 and 4D. Did not mind at all making a small donation to his site, as it really helps keep this all alive. I also have a plethora of diskettes I've garnered when picking up stuff in lots that I will be sending to him eventually.
Sometimes it's fun to figure this stuff out on your own, but having at least a good boot disk to start with would make life much easier.

Good Luck! B)
 
The other benefit is that Ira is nearer to you than I would be. But if you need some boot disks I can donate a couple. Model 4 and Model III boot disks. Just let us know.
 
Just so you know: the upper drive is known to have issues when regularly used. This is a heat-related problem that's known to cause failure. I recommend a cooling fan installed on the case top or near the rear.
 
hi,
I, too, have a working Model 4. If you are still in need of a boot disk, I can also share ( send ) you a copy. I picked mine for $40 CDN...still works and came with some disks. It still working last summer before I packed it for the winter.
For now, I am still struggling with my PET 2001-8 trying to resurrect it...
 
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