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Model III - Repairs and Gotek Experience

M

mbliss11

Experienced Member
Joined
Oct 31, 2022
Messages
208
Location
Maryland
Just wanted to share my experience repairing and using a gotek with my model III. This computer has been a labor of love let me tell ya. I picked it up in a lot and the only thing it did was power on. The crt worked increased brightness and saw raster and the disk drive lights came on but nothing appeared on screen and nothing booted from the 2 floppy drives. Could not hold break and reset into basic either. Was a 16k version per the keyboard but after opening it up found out it was upgraded to 48k. Could have been around same time the disk drives were added.

Cleaned and lubed the drives and eventually was able to get trsdos disk that came with it booting but the keyboard was dead in the water. Later learned that the model 3 keyboards are notorious for carbon build up and are a massive pain to get working again. Let it sit on the shelf for a bit until the trs80 bug bit me again and decided to tackle the keyboard. Needed to desolder every switch, open them up and take them apart, polish internal contacts with pencil eraser and ipa, put them back together and resolder. Good tip to check resistance on the switches before and after clean to make sure there is improvement before resoldering back in.

Took a bit of time but finally got a working keyboard again. After that cleaned pots on the brightness and contrast knobs with contact cleaner. Then serviced the power supply rifa caps.

I really love the modern tech that the community has come up with for these old computers and have at least a gotek in most of my systems. My buddy 3D printed a bracket for me and I flashed flash floppy on a spare gotek I had. Saw a great video on YouTube of someone doing a gotek mod on a model 4 and they threw a drive select switch on their gotek to switch between 0 and 1 with physical drive. I did the same mod.



Hooked everything up and then went to try out software. You need to change images to hfe format based on this GitHub:

github.com

GitHub - GrantMeStrength/TRS80gotek: Configuring a TRS-80 Model 4 to book from a gotek floppy emulator and FreHD system

Configuring a TRS-80 Model 4 to book from a gotek floppy emulator and FreHD system - GitHub - GrantMeStrength/TRS80gotek: Configuring a TRS-80 Model 4 to book from a gotek floppy emulator and FreHD...
github.com github.com

And another good resource:


I tried numerous dmk files to hfe and none of them would boot or registered on the gotek. DONT USE DMK FILES. Use dsk files. Once I had that revelation all was well and I have finally been able to throw some more software on this thing. Has been fun playing games on it. 27485926-5D78-4958-8CE9-D48E6667B1F8.jpeg

BC546812-C327-4241-9A42-0BEDE0BC8977.jpeg
 
Wow! What a project! Didn't know the keyboard was such a thing with the Model3 (I have a model 4 has never needed any fixing) - that first video is mine :)
Labor of love for sure. Way to stick with it! Super nice job!!
 
Oh so cool!! Thank you so much for making that video and sharing that mod! Have you done anything else with your model 4? Yea you sure got lucky with not having to deal with these model 3 keyboards they are a pain in the rear haha :)
 
mbliss11 said:
Oh so cool!! Thank you so much for making that video and sharing that mod! Have you done anything else with your model 4? Yea you sure got lucky with not having to deal with these model 3 keyboards they are a pain in the rear haha :)
Click to expand...
Happy to see someone found it helpful!

Nothing else to do on mine - it's actually a Model 4D - I got very fortunate with it - it came with the original hi-graphics add-on card and 128k of memory.
I saved the drive the Gotek it replaced in case I wanted to restore it back to original (original 4D drives are tough to find)

I have another video where I restored the external 5Mb hard drive that went with it (a whopping $3k back in the day!)

I think you already figured out how to move files to the Gotek - for any others out there (using a PC):

Download TRStools
Load TRStools and make a NEW file
JV3 80TRK DS DD
Push files into it

Drag into HFE emulator
Export as HFE
 
Just a note on what "Notpizza tonite " mentioned. using 80tracks DSDD is great except some DOS TRS-80 model III does not support it without hacks, namely the TRSDOS 1.3
Also in NewDOS 80, you will need to make specifications in this case in "pdrive" for it to be able to use it, but in LDOS 531 this would be direct usage.

if you need further help with gotek on model III let me know.
 
Well, looks like I am going to need to open her up again. Was getting error 25 and 35 trying to load some programs and did a mem test.
27D52D2B-4853-493E-BF7E-C92686490768.jpeg
 
I replaced the ram at U32 and did memtest and it is back in action. I had spare 4116 chips but they were 25ns instead of the 20ns that was currently in the machine. It did not seem to make a difference. Any reason that could be a problem mixing rams with different timings like that?
 
That's more likely 250ns vs. 200ns. But, if it's working without hiccups now don't worry about it. It's common for parts labeled as slow to actually test and work at faster access times. Just more of a crap shoot.
 
Thanks my mistake on the timings. Yea everything seems to be working just fine with it now I’ll consider it fixed and functioning until something inevitably goes wrong with it or I want to upgrade it further haha this hobby keeps you on your toes
 
I've been struggling getting my TRS-80 running a gotek. It sees it but doesn't boot. I've used goteks on ibm PC based and my Amiga 500s..just this machine hates me. I've tried to follow the few YouTube videos but my results differ. I do plan to get a lo-tech ide device installed once this gotek running. Any help or things to try. Maybe a thumb drive image presetup...I donno would make me happy. Thanks.
 
Huh do regular disks boot? Is the gotek in the disk0 position? If you have the disk1 cable plugged into the gotek it won’t boot the disks that is what the switch is for that NoPizzaTonite modded it allows you to switch between the gotek and other floppy. Can you boot to basic?
 
mbliss11 said:
Huh do regular disks boot? Is the gotek in the disk0 position? If you have the disk1 cable plugged into the gotek it won’t boot the disks that is what the switch is for that NoPizzaTonite modded it allows you to switch between the gotek and other floppy. Can you boot to basic?
Click to expand...
With the gotek unplugged and normal floppies it boots fine. Boots into basic. I understand nopizzatonights mod. Very simple I'd switching. After posting this I'm almost thinking should I be using hxc or flashfloppy firmware?
 
rcoonjr said:
I've been struggling getting my TRS-80 running a gotek. It sees it but doesn't boot. I've used goteks on ibm PC based and my Amiga 500s..just this machine hates me. I've tried to follow the few YouTube videos but my results differ. I do plan to get a lo-tech ide device installed once this gotek running. Any help or things to try. Maybe a thumb drive image presetup...I donno would make me happy. Thanks.
Click to expand...
Here are some of my gotek OS images
 

Attachments

  • TRS804D_OSImages.zip
    642.5 KB · Views: 46
Note these are for my Model 4D so I think they may be made for a DSDD - this may make a difference for your machine
If this is an issue, you may need to see what mbliss11 can help you out with
Also - if you have a Model 4D with an external hard drive, I have images with drivers for that as well.

Note what Patrick.B pointed out earlier:
... using 80tracks DSDD is great except some DOS TRS-80 model III does not support it without hacks, namely the TRSDOS 1.3
Also in NewDOS 80, you will need to make specifications in this case in "pdrive" for it to be able to use it, but in LDOS 531 this would be direct usage.
 
Last edited:
NoPizzaTonite said:
Note these are for my Model 4D so I think they may be made for a DSDD - this may make a difference for your machine
If this is an issue, you may need to see what mbliss11 can help you out with
Also - if you have a Model 4D with an external hard drive, I have images with drivers for that as well.

Note what Patrick.B pointed out earlier:
... using 80tracks DSDD is great except some DOS TRS-80 model III does not support it without hacks, namely the TRSDOS 1.3
Also in NewDOS 80, you will need to make specifications in this case in "pdrive" for it to be able to use it, but in LDOS 531 this would be direct usage.
Click to expand...
I'm using a model 4 (not the d... wow that sounded bad)
NoPizzaTonite said:
Here are some of my gotek OS images
Click to expand...
That worked. I bet anything I used the setup that GrantMeStrength did up. And I think it doesn't like that I don't have a FreHD installed. I'm gonna more that from the USB and see what it does without it on there. I think were on to something !!! Thank you very much!!
 
I have Flash Floppy on my gotek. In addition to a few hfe images that I use on my Model III (mine has been upgraded to 48K) I have also included my flash floppy config file. I don't remember if I modified anything in the config file but feel free to use it I can confirm it works on my system. Give these a try they should be bootable images.
 

Attachments

  • TRS80Gotek.zip
    139.6 KB · Views: 48
You guys are amazing. These two files helped! I'm thinking my whole issue is converting the DSK images to HFE. Gonna try it again and see if I can do it without assistance... :)
 
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