Looking at the TRS-80 Model x Series - Part 4 (Familiarization)

Bill Loguidice's picture

(Part 3 here) Welcome to Part 4. I've still been busy with the book and related stuff (Gamasutra bonus chapters, bonus images, documentary), as well as the usual family thing and a lingering illness (a four week "cold" that my wife and I are still suffering with), so I really haven't had the time or energy to get downstairs much to mess with the TRS-80 collection again until last night. Needless to say, even though I only spent about an hour down there, it was very educational. I hope to be able to devote a small block of time each night to making progress and formally blogging with images and/or video when there's something particularly interesting happening.

Essentially I first wanted to make sure the TRS-80 Model 4 (the big desktop all-in-one computer) was functioning, as I was going to use that as my main system for a while and get a few game blogs out of the way before moving on to the more challenging Model I stuff. Unfortunately, when I plugged it in, nothing happened. Luckily, after a while of turning the power on and off it finally cycled up. Unfortunately, disk drive 0 (the bottom drive) didn't sound like it was spinning cleanly (it sounded like it was struggling). Nevertheless, after several presses of the reset button and a few more power cycles, I was finally able to boot my Y2K fixed disk operating system from LNW, which is TRS-DOS compatible and improved (though the drive still squeaks a bit as it spins). I then proceeded to try to access several disks in drive 1, but couldn't read anything, though I wanted to keep trying since there was no guarantee that any of those disks were ever viable in the first place. Luckily I had a brand new unopened disk of public domain BASIC games that did read, so perhaps those other disks were just that, bad. On the downside, the keyboard was initially unresponsive, but once I began exercising the keys, they came back to full function again.

Certainly one of the downsides of having the volume of hardware I have (320+ systems) is that there's not enough time to "exercise" the systems, meaning power cycle, leave running a while, press the keys, etc., which helps keep the things functional (helps stop things from drying out, etc.). It still seems to take several power cycles and presses of the reset button to get it to register power and/or see and then a boot a disk. Once it's working, though, it seems to stay up and stable and at 100% function, which is a positive.

Obviously one of the big issues with using command line based vintage hardware is remembering even a few of the key commands to make things work. It's fun for about 20 minutes to try various commands from memory, but after a while it's just best to refer to the documentation and do it right. Needless to say, I pulled all the relevant Model 4 documentation (or Model I/III stuff that applies) and got the commands for accessing files on disks from BASIC (you need to type "BASIC" at the command prompt to go to BASIC, then you do Load"programname/BAS" to load a program--I'll go into more detail about these commands next time), since you don't start out with access to BASIC from the DOS, which like CP/M and early PC-DOS relies on loading commands off the floppy disk.

I did try a few of the BASIC games, and they were all text-based dreck, some worse than the kind you'd type in from magazines. I'll have more to say about that in the future.

One thing I did confirm was that the Model 4 does not have a serial port, just its standard cassette port (which can also be used to control a speaker with the same cables) and a parallel (printer) port. This precludes it's use with the Votrax speech synthesizer. However, the Model 4p does have an RS-232C port built-in, so I may be able to use that. Of course, there's always the Model I and it's expansion box, but I'll need to investigate that further as well.

As I had mentioned in an earlier blog, I had salvaged some parts from a broken Model III to put in this Model 4, including I believe one of the disk drives and some memory chips. I need to find an easy way to check how much memory my 4 has. It has 64K standard, but I may have expanded it beyond that (I believe you needed 128K to run CP/M, but I could be misremembering). There's no easy way to check, so I'll have to look through my documentation for a program to type in or something.

Sorry there are no photos or videos this time around, but I really needed to see what was what before having to worry about "frills". I hope to have a more visual presentation next time.

See you at part 5!

Comments

Calibrator
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Joined: 10/25/2006
64 KB are enough for CP/M.
Bill Loguidice wrote:

It has 64K standard, but I may have expanded it beyond that (I believe you needed 128K to run CP/M, but I could be misremembering).

Do I sound like Bill Gates now? ;-)

take care,
Calibrator

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Bill Loguidice
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Clarification
Calibrator wrote:
Bill Loguidice wrote:

It has 64K standard, but I may have expanded it beyond that (I believe you needed 128K to run CP/M, but I could be misremembering).

Do I sound like Bill Gates now? ;-)

take care,
Calibrator

No, I'm well aware that you only needed 64K to run most full versions of CP/M (there were of course versions of CP/M available for far less memory), but I think on the Model 4 for some reason you needed 128K. I'll have to double-check but I'm pretty sure I remember that being the case odd as it is.

Vintage Games book!
Xbox 360: billlog | Wii: 1345 2773 2048 1586 | PS3: ArmchairArcade
Bill Loguidice, Managing Director | Armchair Arcade, Inc.

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Bill Loguidice
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Hmm, I guess I need to check

Hmm, I guess I need to check under the Model 4 computer to see if there's an RS-232c port there...

Also, it seems to indicate here that you can run CP/M with just 64K: http://www.classiccmp.org/dunfield/trs80/index.htm (another PDF on there for memory seems to indicate that I might be missing a chip to activate the full 128K, which is certainly possible)

I also wonder if I have two matching capacity disk drives in there, though it's really irrelevant for my purposes at this point.

Vintage Games book!
Xbox 360: billlog | Wii: 1345 2773 2048 1586 | PS3: ArmchairArcade
Bill Loguidice, Managing Director | Armchair Arcade, Inc.

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Mark Vergeer
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Joined: 01/16/2006
Yes 64K was enough to run CP/M

The computer in Highschool was also running CP/M with 64Kb. I actually never saw any of the TRS-80's counting more than 64Kb. I think it was a model 4, the rest were all model 3 ones.

I just had a memory of this small little obnoxious popular wise-ass kid in highschool - who always thought he knew everything - being convinced he could run his dad's MS-DOS disks in the TRS-80 because he somehow thought that the similar CP/M command prompt meant it could run MS-DOS. We actually had a bet and of course I won and the kid bit the dust hard. He never actually recovered - and I had taken his place. Probably because of that and because of my fancy animations. He was always trying out nice and fun animations on the system - like little demos. Well this bet and my increasing skills on the trs-80 actually landed me the job programming the C64-oscilloscope thing for the science department.

Xbox 360: Lactobacillus P | Wii: 8151 3435 8469 3138
Armchair arcade Editor | Pixellator | www.markvergeer.nl

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