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Woot! New Model 4 Owner!

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mbbrutman

Associate Cat Herder
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May 3, 2003
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Most of you know me as a PC family enthusiast. My first PC type machine was a PCjr. My first machine ever was a Timex Sinclair 1000.

But before both of those were frequent window shopping events at Radio Shack. The Color Computer and the TRS-80 line were too expensive and I was way too young to have/need a computer, but they were there at the local store. The TRS-80 Model 4 was a particularly nice looking machine ... very professional looking.

Erik rescued a Model 4 a few weeks ago. I decided to 'rescue' it from him, and now it is here in the house. It needs some TLC, but I'm really excited (as excited as I get at least) to be exploring another machine architecture for the first time in many year. This one has two floppy drives and looks to be a non-gate array model. It's going to need some cleaning before I power it up, but it looks pretty good for a 25 year old machine.

We're going to have to start kicking the PC clone Tandy posts into a different part of the forum now. ;-)
 
Very cool! Be sure to post pics of the TRS-80 when you get it clean! I recently explored a TRS-80 Model III, a big change from the PC and PC compatables I have been using. I love my TRS-80, it is very cool looking and productive. Plus, I have a good amount of software for mine. What O/S did yours come with? LDOS? TRS DOS? Mine even came with games on the TRS DOS disk! You seem alot more exited than I was to explore a new architechture, but I guess I haven't been sticking to one thing for as long as you... Heck, the first computer I ever bought was an Apple IIc! What software did you model 4 come with? What manuals? What plans do you have for your newest machine? I'm curious to know what was different between the model III & 4. All I can tell is color of the case. What is the size of your floppy drives and is your monitor monochrome or color? How much RAM?

--Ryan
I guess I could always look at the rescue mission thread, but the pics there and info are lacking of detail.

My TRS-80 Model III(for comparision, of course):
Pic1, Pic 2, Pic 3, Pic 4, Pic 5
 
Software is minimal - it looks like it has TRS DOS 1.3 on a single diskette. I'm going to need to get a set of usable boot diskettes and software. Two original manuals came with it.

The machine has two single sided floppy drives and the serial port option, all of which look to be factory original. The downside of this particular machine is that it needs some serious work on the keyboard. Erik warned me, and it is bad .. I'm going to have to learn how to disassemble and clean/rebuild the keyboard in order to do anything useful.

It will be interesting to be on a Z80 machine. I'm already thinking about a minimal TCP/IP implementation, but I'll need a cross compiler and an assembler to get started. That's a long way off. I'd also like to find a copy of Zbasic - I was a Zbasic fan on the PC, and I know that they had Tandy versions too.
 
I had a few different revs of TRS-DOS and LSDOS, but I think the pain is imaging up M4 disks because of (I think) the indexes or o something? I forgot what DDunfield said...

I also have Montezuma CP/M 2.2 for the M4 as well.
I have a (well, 2 - one for parts) Model 4p. I grew drooling over the one my uncle had, because it was just, well, cool.


T
 
Welcome to the world of Tandy!

I had years of fun with my model 1 clone. Now that I'm exploring other systems I can't help but be impressed just how sophisticated those TRS-80 Z-80 Dos'es were for their time compared to early PC-DOS/MS-DOS and CP/M.

Of course I always knew they were good ;)

A Model III or IV would be so cool to have. Perhaps I should add it to my list? They really look like what a computer should have looked like in those early micro days. Problem is (as always here) scarcity and therefore shipping costs. They would also need to be packed carefully to get to New Zealand. Being dropped from a 747 onto tarmac can reseat chips but it's not too healthy for VDUs :)
 
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Erik packaged this one well enough to survive a trip to Mars. The machine was in bubble wrap, tight in a box, and then the box was packaged again in another bigger box with styrofoam packing 'peanuts'. The box in a box technique is great ...

I am going to have to break the 'Warranty Void If Broken' seal on the bottom of the machine. There is no way to clean and repair the keyboard without doing that. I'll take pictures before I enter the case ... nobody has been inside the machine in 25 years, so it is a bit like breaking into a crypt. It is not usable as it is now, so it has to be done.
 
Yep, a 1 floppy system. I hope to find a second one some day, when I have more money. Hehe, nice vid! The graphics on the Model I were a bit worse than the Model III! If you look closely, the monsters my Scarfman is running from look like one from the PacMan games! Oh well, the Model I was probably already at it's limits with just that! My machine has no sound, but if I setup a cassette player on it, it can.

Mike, I think my TRS-80 has a serial port, too. I know for sure it has a floppy expansion port and a printer port, and seem to recall another port of some sort. I will know for sure in a few months(2) when I am packing my things. Right now it is under the bed, though. I have the same version of TRS-DOS. According to my manual, TRS is pronounce "Triss" not trash. trash just rolls of the tounge, even though these machines are wonderous.

--Ryan
let me know if you need any info from my manuals, copies of disks, or *gasp* any help.
 
Yzzerdd said:
The graphics on the Model I were a bit worse than the Model III! If you look closely, the monsters my Scarfman is running from look like one from the PacMan games! Oh well, the Model I was probably already at it's limits with just that! .
Click to expand...

No, both the M1 and M3 have exactly the same graphics. Thing is in that clip, I kept eating the energy balls so the monsters never had a chance to revert to predators. Right at the beginning of the clip they are normal and at the very very end, of the clip a couple of them start to revert. A flashing one that was just starting to revert was the one that finally got me (-:
 
Ah, I see. I didn't notice they looked normal in the begining!

Mike, my keyboard was a little bad when I got mine, too. The "B" key and another that I don't remember were way bad. You had to press them rather hard to make them work, and they usually printed that charecter a few times. I just excersised the keys, and they seem to be fine now. I don't know how to pull out the keyboard as I never tried, but to get the top off, there are screws on the underbelly that must be removed. Mine had the original warranty label tore off, but apparently it was serviced at a radioshack loacation, as a new one was placed over the hole. I tore through that though, upon initial inspection of the machine. I dunno what needed to be serviced or added inside, I just know it appears to have been opened by a qualified radio shack store. Good luck on your adventure!

--Ryan
 
mbbrutman said:
I am going to have to break the 'Warranty Void If Broken' seal on the bottom of the machine. There is no way to clean and repair the keyboard without doing that. I'll take pictures before I enter the case ... nobody has been inside the machine in 25 years, so it is a bit like breaking into a crypt. It is not usable as it is now, so it has to be done.
Click to expand...

Use a hair dryer to heat up the warranty label and, when the glue softens, peel the label off and stick it to some waxed paper. Heat it up again before putting it back on.
 
Good idea. I was going to try to find a way to preserve the label, or at least attempt to. If it does come off cleanly, I probably will save it and not put it back on the system.

I have my tools, my Radio Shack 'Control/Contact Cleaner & Lubricant', and a digital camera ready to go.
 
Let me know if you have any trouble creating disks for it. I have it down pat here. I also have several boxes of disks, and quite a library of software.

Kelly
 
I just completed my first attempt to clean the machine and repair the keyboard.

Getting the machine open is a little tricky - I read the procedure in the Sams book and checked on the ClassicCmp mailing list, which was a good thing to do. Apparently the CRT is attached to the top of the shell, and the neck is exposed and fragile. I was able to get the machine open and back together with no incidents.

The drives were cleaner than I thought they would be. They are both cleaned and lubricated now.

The keyboard is a problem. I removed the keyboard from the machine and examined it carefully. The construction of the keyboard is not conducive to individual key repairs. You can't get the key mechanisms apart without first desoldering *all* of the keys from the printed circuit board. If one were to get desperate enough one would do that, then take apart the individual switch mechanisms to find out what the problems were.

I'm not at that point yet .. I'd rather sit and think about this for a bit. I'd also like to find a spare keyboard mechanism from a dead machine to practice on first.

The rest of the machine looks pretty good.

Kelly - at some point I'll take you up on the software. This is an entirely new beast for me. When I get more advanced I'll be looking for cross compilers so that I can write code on a PC and run the code on the TRS-80. A 48K or 64K Z80 machine is more than capable for running code, but a C compiler is going to be a stretch. ;-)

Druid - The label is off and preserved; I used your hair dryer suggestion.
 
Glad the box arrived intact and I'm more glad you're having fun! :)

Yeah, from the ccTalk posts that keyboard is gonna be more effort than I thought.
 
Good old Tony D ... only he would desolder every key on that circuit board just to rearrange the dodgy keys to a less annoying place.

The machine is going to the side for the moment until I figure out what to do with the keyboard. 'Computer News 80' in Wyoming probably has parts and probably also can do the repair work. I can wait for a second keyboard to work with/canabalize. And lastly, Tony mentioned that the keyboard is just a matrix of switches. With a little reverse engineering I can probably construct a replacement keyboard. It might not be as nice as the original, but I wouldn't have the guilt of cannabalizing another machine.

And of course, I'm open to other suggestions ...
 
mbbrutman said:
The keyboard is a problem. I removed the keyboard from the machine and examined it carefully. The construction of the keyboard is not conducive to individual key repairs. You can't get the key mechanisms apart without first desoldering *all* of the keys from the printed circuit board. If one were to get desperate enough one would do that, then take apart the individual switch mechanisms to find out what the problems were.
Click to expand...

The proceedure for removing individual keys is as follows;

Pick the target key

Desolder the two (or four, depending on the keyboard model) legs of the target key

On the left and right sides of the key, on the upper metal deck, where it just protrudes above the metal, there are tabs. Squeeze and hold these tabs in against the body of the key and rock the key back and forth while pulling upwards (I use a pair of curved forceps for this).

Replace the key (I believe that on the four-legged model, one set of legs are further apart than the other, so, watch your orientation) and re-solder.

Depending on what type of keys you require, I may stll have a few laying around, but, they are damn hard to find. The two-legged ones can be salvaged from an scrap Apple ][+ keyboard.

Hope this helps some.
 
mbbrutman said:
Good old Tony D ... only he would desolder every key on that circuit board just to rearrange the dodgy keys to a less annoying place.

The machine is going to the side for the moment until I figure out what to do with the keyboard. 'Computer News 80' in Wyoming probably has parts and probably also can do the repair work. I can wait for a second keyboard to work with/canabalize. And lastly, Tony mentioned that the keyboard is just a matrix of switches. With a little reverse engineering I can probably construct a replacement keyboard. It might not be as nice as the original, but I wouldn't have the guilt of cannabalizing another machine.

And of course, I'm open to other suggestions ...
Click to expand...

Instead of cannibilisation, could you not just replace the keyboard with one from a dead machine (assuming you could find such a beast)?
 
Druid6900 said:
The proceedure for removing individual keys is as follows;

Pick the target key

Desolder the two (or four, depending on the keyboard model) legs of the target key

On the left and right sides of the key, on the upper metal deck, where it just protrudes above the metal, there are tabs. Squeeze and hold these tabs in against the body of the key and rock the key back and forth while pulling upwards (I use a pair of curved forceps for this).

Replace the key (I believe that on the four-legged model, one set of legs are further apart than the other, so, watch your orientation) and re-solder.

Depending on what type of keys you require, I may stll have a few laying around, but, they are damn hard to find. The two-legged ones can be salvaged from an scrap Apple ][+ keyboard.

Hope this helps some.
Click to expand...


It does - this tells me that Tony was going overboard and that individual keys can be repaired.

I did see the tabs that squeeze against the body of the switch, but I could not tell if the switch body would come up through the metal tray if it were free of the circuit board. That I would be willing to experiment with.

These were 'four-legged' keys. Any idea on where spares come from?

[I looked at Cherry (based in Wisconsin) and I'm thinking of getting some samples to see how close I can get with new parts.]
 
mbbrutman said:
These were 'four-legged' keys. Any idea on where spares come from?
Click to expand...

I think the ones I have laying around are the 4 legged ones. I will check next time I venture back into the basement.

Ok, that confirms what I thought, the Cherry keyboards are the 4 leg ones and the Alps keyboards are the 2 legged ones.

I might be able to dig up the Cherry part number for the keyswitch if that would help any.
 
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