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Erik
July 28th, 2003, 08:52 AM
I finally took a "weekend off" from my hectic pace of house-hunting/packing/(hopefully)moving etc.

Even so, I still couldn't muster more then about 6-8 hours for playing with my collection and that was with really, really trying to.

Here's a rundown of some of my Vintage Computer related projects, for those who care:

Project: ASR-33

Goal: Get my ASR-33 fully functional and hooked up to my Altair 8800 for the VCF in October.

Progress: I managed to put about 4-5 hours into trying to resurrect my ASR-33 teletype. It wasn't all that productive but I learned quite a bit about its operation and got some of it figured out. I've got a long way to go, I think, unless something obvious (like a broken spring) pops out at me.

Status: The machine basically works. It will punch tape, read tape and type. The only problem is that the letters it types or punches don't correspond to what key is depressed more then half of the time. . . this presents a problem. :)

Next Step: Keep plugging away and maybe find a local expert who can speed along the project. . .

Project: TRS-80 Mod. I, Step II

Goal: Get the TRS-80 working again.

Progress: Spent about 2-3 hours with this system this weekend (much of it unpacking and then re-packing the box!) Obtained a new monitor that actually works. Hooked up the system and did a more complete analysis of its current operational status.

Status: Main unit and monitor function well. The expansion interface appears to be in need of some assistance. Cursory inspection didn't yield anything obvious. If the expansion is turned on, the screen displays garbage at boot. If it's off, I have a working 16K system (with no access to the disk drive)

Next Step: I'm not sure what's broken, but the only socketed chips on the expansion board are the 4116 RAMs. Those will be replaced when I can obtain some chips. Hopefully it's that simple.

I didn't get to tinker with any of my other projects this weekend, but here's a partial list of other front-burner items:

CompuPro build: I have a CompuPro chassis with about 2 dozen cards and an external 8" disk enclosure that needs to be configured and booted, assuming everything works.

S-100 system analysis: I have 3 S-100 systems (mostly based on Teletek cards) that need to be cleaned, cataloged and tested. 2 are earmarked for other folks so I need to sort the stuff that came with them and box them up and ship them out!

Commodore Pet: I really want to get this beast working better. The machine works great, but it needs a working tape drive. One is on the way so I hope to play more soon.

Altair 8800: I have a second 8800 that was built late in life (probably in the mid 1980s) so it doesn't conform to the "standards" of how these machines should be built. I've now got almost everything I need to restore it to "built in 1975" condition, except for the time. . . Hopefully I'll find the time to both perform and document this effort soon.

Anyway, that's enough rambling for now. I hope you enjoyed my brain-dump! :D

Erik

barryp
July 28th, 2003, 08:16 PM
Project: ASR-33

Goal: Get my ASR-33 fully functional and hooked up to my Altair 8800 for the VCF in October.

I've never worked on an ASR-33 but the FAA used them, mainly in Flight Service Stations. If you know anyone there locally who does or did work for FAA as a technician that's a possible source of info.

I do remember that the guys who worked on the ASR-33 were <always> working on their ASR-33s.

Erik
August 8th, 2003, 09:22 AM
Well, I managed to get almost no work done on the ASR-33. I've figured out a few things and gotten it working better with the efforts I have put in, but it's by no means "working" yet since it mistypes characters about 5-10% of the time.

I have determined which code-bars (or something attached to them) are failing, but I haven't figured out how to remove the typing unit from the chassis to check and lube these.

I did, on the other hand, get the TRS-80 Model I working. It's really a neat little machine. As it turned out, most of the problems were operator error. . .

I also ended up pulling out my Zorba for some testing and playing. Someone requested copies of the boot disks so I had to make sure everything worked. It does. . . :D

olddataman
September 15th, 2003, 01:37 PM
Eric, in my former life as the honcho maintenance guy of on-line systems at Brookhaven National Labs, I had about three dozen ASR-33's that had to work 24/7. I had a technician trained by Teletype Corp. on 33's and 35's, and he was very good so I didn't have to get my hands dirty too often. What I remember is sketchey, but one or two items stand out. The first thing to check out is the timing adjustment. If the timing is not wthin the allowable range the machine will garble both received data and data being transmttled. The machine works like all subsystems are independent and all are timed by the mechanism at the rear left corner of the unit. There is a lever that one slides around the clutch that sets the relationship between the baud rate and the character construction.
If the thing types correctly sometimes and the next time garbles the same character, the trouble is not in the code bars. If they are so loose they don't work I would look for another "surplus" machine to get the keyboard from because believe me it is no fun to take one apart and try to get it back together. One of my guys dropped a keyboard and we discovered that it cost more to put one back together than to buy a new one whiich in 1965/66 cost $35.00.
If you have access to SCCS Interface magazine (first dozen or so isssues) there is an excellent series of articles describing the theory of operation and the maintenance of the Model 33. I don't remember to whom I sold mine now, but I think Bob Stek has a set.