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need help with technical problem

C

Computer Collector

Experienced Member
Joined
Jan 22, 2005
Messages
283
As you know, the TRS-80 model 4 is a beautiful little machine. I got mine for free; a certain thrift shop around here was throwing it out! It has 2 single sided drives. the one on top is called :1 and the one on the bottom is called :2.
Anyway, everything works great except for disk drive :1. For some reason, something just isnt working correctly. Ira Goldklang was nice enough to let me have some software, so I could actually use the machine. However, some of it is in "data disk only" format, which means it has to run off of drive :1. Unfortunately, when I type in "Dir :1" instead of listing the directory, it gives me scrabbled letters if anything, and then often says "error 03". I tried cleaning the drive with one of those floppy disk drive cleaning kits, but still the same problem. do any of you know what the problem could be and what I should do? the other drive, disk drive :0 works great, thankfully.
 
Well, if it's booting into TRSDOS/LDOS/whatever, then the drive can't be completely shot. At least it's able to read track 0. Mebbe the head is sticking when it tries to move to another track, in which case, a little lube might do the trick. (IIRC, TRSDOS keeps it's directory on track 18). If lubing the tracks doesn't help, then the best thing will be to find a replacement for it. From there you have more than one option. You don't have to find another SSDD drive, a double-sided drive will work just fine. Some people even install 3.5" drives in thier Trash-80s. You probably should move the working drive into the #1 position. Don't worry about jumpering the drive, just leave it like it is. The TRS-80 uses the cable for device select. If nothing else, at least you could still run it as a single-drive system until you can arrange a suitable replacement. Good luck, and let us know how it works out.

--T
 
Sounds like you've only gotten your "feet wet". The drives on the Model 4 are :0 for the lower drive and :1 for the upper drive. The boot disk goes in the lower drive. *CAUTION* Use the upper drive sparingly or use a cooling fan as the design of the case makes cooling the upper drive difficult. Ira is a great help but can be difficult to access because of his job. I'll try to help where I can. I have both a rare green-screen 4 and a gate-array 4P. They're good machines1
 
of course, the other option is purchasing an external mini disk drive to hook up to the bottom of the machine, in the slot next to where the printer hooks up. Actually, I already have a couple of external COCO drives, but apparently I need model 4 drives. Are they easy to find? I would need one of those including the cable to hook it up, of course. (since I dont have one)
Perhaps going this rout would be easier than replacing my upper :)1) drive.
 
Your Coco drives probably are compatible with the faulty :1 drive. Replacing the drive is difficult. Doing things wrong can blow a picture tube; I've done it. You will need a cable to connect external drives. Computer News 80 has these for sale. You will also need to turn these drives on in LSDOS if they aren't on already.
 
*CAUTION* Use the upper drive sparingly or use a cooling fan as the design of the case makes cooling the upper drive difficult.
Click to expand...

wow, i had no idea about this.

i sure had a wrong impression of my Model IV... looking at the top and back of the computer, and not feeling much heat, i always thought that this machine was well designed. but maybe why i am not feeling much heat from the machine, is perhaps because the heat is trapped inside :)

chris
 
I assure you it gets very warm! Attempting to remove that drive isn't for the faint of heart. I know. I need to remove the case and adjust the drive speed; it's 290 RPM. It should be 300 plus or minus 3. Try cutting slots in the case upper or on the side and mount a regular PC style fan that runs on AC or find a DC power supply. The drive will run cooler and longer. Many was the time I overused that drive and the diskettes got noticeably warm. I started getting load "gronking" noises and read errors.
 
Your CoCo drives are compatible with the Model 4, it's the cabling that is different. The TRS-80's external drive cable has certain pins removed from the connectors to select the device. Different pins are missing to select device 0, 1, etc. If you can get your hands on one, look at the connectors and make a note of which pins are missing, then you should be able to convert the CoCo cable to match. (Mebbe someone here can give you a hint which pins to remove). Which CoCo drives do you have, half-height or full-height? The full-height should just drop-in to replace the faulty drive in the Mod4, should you choose that route. I really don't remember if you'll have any difficulty trying to boot from an external drive, even if it is cabled correctly. You may have to have the internal drive working to boot from.

--T
 
While browsing eBay today, I came across this store, specializing in TRS-80 parts, etc. Thought it might be of interest. (Thier prices seem reasonable enough).

--T
 
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