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Rescued a TRS-80 Model I...

Al Hartman

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Well...

One came up today, and I couldn't resist. It was the last model E/I, with a Percom Doubler, RS-232 Board, and a power supply. I scored it for $150.00 + $35.00 shipping and handling.

I'll be eating peanut butter and jelly sandwiches for the next six months... But, now I should have a fully working Model I system.

If I can get the other system going, perhaps I can sell it to pay for this E/I. I'm short a power supply for it, however.

Since I have this, I'm going to shelve the Disk-80 for now. And, I have to decide whether I'm going to keep the Aercomp Doubler I bought (it arrived today), or sell it. These puppies are so rare, I'm leaning towards keeping it. I wish I knew what happened to my LNDoubler 5/8, and what in the world possessed me to ever sell it. I also don't know what I did with my original Percom Doubler (unless that's what's currently in my original E/I).

I really can't wait to fire up a fully working Model I...

Somewhere, I also have a Tandy Doubler if I can find it.
 

NF6X

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Congratulations on the E/I! I think I saw that one in my eBay searching. I hope it'll help you get your system up and running.

Also, let me tell you about a little trick: If you put jerky into ramen noodle soup, the jerky reconstitutes in the boiling water and turns back into meat. Peanut butter and jelly sandwiches are a wonder food, but a little variety now and then is good.

The jerky trick also works in cup-o-noodles (or cup-o-crap, as I call it), making the stuff nearly edible. But it turns out a lot better if you splurge on some real Top Ramen.
 

Al Hartman

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I was kidding about the PB&J (I hate PB&J).

I couldn't eat Ramen with Jerkey in it. Too much Sodium.

I have to sell all the extra stuff I have here. I have 6 months, no interest on buying that E/I. So, I got 6 months to fix up and sell my extra Model I (no doubler or RS-232), sell off some extra Coco stuff I have here, and try to sell off a ton of PC ISA and VL-BUS cards I have.

I also have a couple of Macs, and some old Powerbooks to sell off. If I can, I think I'll have plenty to pay for the E/I, Doubler, and Disk-80.

I've gotta fix the keyboard on the Model III, and then decide whether to keep it, or sell it. And fix the Model I I just got from an estate sale.
 

Al Hartman

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I haven't started working on it yet, but I hooked it up as I was testing the E/I I just won on eBay, and here's what the video looks like:
P081514_1612.jpgP081514_1612[01].jpg

The first one is just at power on, the second one is after pressing [ENTER].

If I type: ? MEM[ENTER]

I get more graphics.

Should I try replacing video memory, main RAM or the 74LS144 chips?
 

TRS-Ian

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Hi Al, I would have a read of page 34 of the M1 Tech Ref handbook and then have a look at Z63.

(Z63 being one of the 2102 video SRAMs).

Ian.
 
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Al Hartman

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Thank you Ian, I'll do that.

I have two 21L02 chips I bought on eBay as I was going to add Lowercase to my other unit. It ended up already having the mod. So, I can replace up to two chips without having to buy more.
 

Al Hartman

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I replaced Z63, and the system is working. I hooked it up to the new E/I I just bought, and it showed 48k and booted to DOS.

Tomorrow, I'll hook up the E/I I got with it, and track down a copy of Super Utility, and burn it in.
 

Al Hartman

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I couldn't wait. I hooked up the other E/I. No disk access. Holding BREAK on booting only got me 16k.

I cleaned the contacts with alcohol, and then reliably got 48k. But, still no disk access.

Since this computer doesn't have a doubler, my thought is that perhaps one had been in there and was removed. Tomorrow, I'll take the E/I apart and check that the FDC chip is plugged in correctly. I can borrow the one from my original E/I if I need to. I'm not touching the known good E/I to test chips.

For kicks and giggles, I hooked up my original E/I. Nothing. No RAM is recognized, no disk access. I'll have to open it up and see what I see inside.

I ran the simple test program we used to use back then:

10 Print MEM;: gosub 10

That puts the return on the stack and slowly counts down to zero, when it crashes. It crashed the first time I ran it very quickly. After cleaning the connector, it worked fine several times.

I need to get the disk controller working so I can run a real memory test.
 
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NF6X

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Congratulations on getting stuff working! That's a neat and elegant little test program. I think I'll try that out my my Model I when I get home tonight.
 

Al Hartman

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I tried opening the E/I (just wanted to try it...), the FD1771 chip was in the socket correctly, and had no tarnish or bent pins. I re-inserted it after checking it, but no change other than that the system now goes right to MEM SIZE? and I don't get the normal hash.

I bought a doubler that had a 1771 on it. I'm going to try that one tomorrow and see what happens.
 

Al Hartman

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The 1771 chip changes the actions of the E/I, but it doesn't boot from floppy. I put it aside for now and went back to the other E/I and keyboard that work.

After struggling for several minutes trying different boot disks, and cleaning the heads of the drive... I finally get it to boot to Super Utility 3.0+. I run the memory test, and it passes.

But, I can't get it to format or boot from any double density disk. There is obviously a piggyback board on the FD chip that I can see through the side holes.

I sleep on it, and this morning I crack the case and find that there's NOT a doubler in there, but a data separator instead.

P8170001.jpg

Luckily, I had bought an Aerocomp doubler for the other E/I, and I put that in. Problem solved.

Aerocomp Doubler 1.jpg

One of my Multidos (1.6D) master disks is bad. I'm now trying to make a new one with imagedisk, but the floppy controller in my 5150 doesn't like single density. I hope I have another copy of Multidos 1.6D somewhere.
 
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