test-drb October 2020

test-drb@ccmp.vtda.org

136 participants
117 discussions

by chentsay＠yahoo.com

Dear Tom, Does your Sun workstation is functional and read QIC -150 cartridge? I have some old 3M 6150 cartridges that was created by Sun Sparc workstation in 2000. One those cartridges, I have some my personal files I like to get them. If you can you read those cartridges, I can pay some money for you? Chen Tsay

4 years

Modcomp computers and documentation

by lyokoboy0＠gmail.com

Greetings everyone, it's Been a while since i posted here. I had picked up some modcomp minicomputers over the past couple years. A modcomp classic, with a nice front panel with binary swiches, similar to a pdp 11. There is a modcomp 32 as well, the machine boots from internal floppy drives. I was eager to pick up these machines, and save them from being thrown out. I picked up all of the documentation as well. Everything. A truckload of os information. I started to scan it all, but about 3/4 of the way through, my scanner broke. The 32 machine was not stored in climate controlled conditions before i picked it up, and is a bit more worn. It is designed to boot off floppys to load the microcode into the cpu... but the floppys... id be supprised if anything survived. Stored in bad conditions. The classic has internal microcode roms and will not have the same troublesome problem. I have been unable to devote the time and space to these machines as i had planned. I have been far too busy working at ibm, i am planning to shut down my side interests and focus on my dec pdp 11 stuff and ibm mainframe. I am looking to see if anyone would be interested in buying these. I spent a great deal getting them moved and keeping them in cool climate controlled storage, i am looking to see if i can get any offers and break even. Keep in mind, they are the size of a computer rack and heavy. I will post back with pictures soon.

4 years

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by jnc＠mercury.lcs.mit.edu

> From: Chris Hanson > My little LSI-11 system doesn't have a usable Line-Time Clock because > it lacks the register, which it expects to be in either an MXV11-B > (M7195) or a BDV11 (M8012). My power supply theoretically supplies the > LTC .. so my preference would be an M7195 ... > Does anyone have one they'd be interested in parting with? The MXV11-B is rare and expensive - I think because it's a Q22 card. The BDV11 is, on the other hand, fairly common, not not too expensive. If you can't find a reasonably-priced one (i.e. <US$50) one on eBait, Paul Anderson used to have some. If he's out, I can probably be convinced to part with one. The BDV11 has on Q18 _terminator_ functionality; there's an ECO to make that Q22,though. FWIW, both the KDF11-B and KDJ11-A have built in LTC's, if a CPU upgrade is feasible for you. Noel

4 years

Manuals, catalogs, brochures posted on Archive.org

by pdp11＠saccade.com

Last year I found a box of material, much of it related to S-100 computers and the Sol I owned in the 1970s. I've scanned it in and posted it to the Internet Archive: https://archive.org/details/@j_peterson Folks researching obscure old devices (Biotech Electronics CGS-808, anyone?) may find something useful. I still have a few documents waiting to scan, but this is 98% of it. Cheers, jp

4 years

IBM 3279 analogue board / schematics?

by mattislind＠gmail.com

I am helping a friend with his IBM 3279 terminal. I got the PSU working after reverse engineering it. Concluded that the SMPS control chip was a standard TDA 2640 in IBM disguise. But of course the thing didn't work with the PSU fixed. A fuse which was in series with the vertical deflection coil on the analogue board went toast together with a 200 ohm resistor in the vertical deflection circuit. https://i.imgur.com/O4YEsdL.jpg At first I thought this had to do with some kind of fault in the vertical deflection coil itself. It measured only 1.2 ohms. But checking the IBM MAP manual revealed that both deflection yokes are supposed to be less than 2 ohms. So there has to be something else. I powered up the analogue board with the 5V and 8.5V that is normally supplied by the PSU (left the 103V unconnected since it used for the HV mostly) just to see what happened. The power consumption was reasonable, 0.3 amps on the 5V and 0.16A on the 8.5V. I then probed around among all those annoying IBM marked chips and square aluminium boxes. I found one chip that had 250 kHz on a pin. The chip appeared to be a divider since there were also 125 kHz, 62 Khz 31 kHz and 15 kHz. It seems to be originating from a square aluminium box. And then I found a signal which was around 20 Hz on another chip. As far as I understand the 15 kHz would fit well with the 64us sweep in the manual. But what is the purpose of the 20Hz signal? Vertical deflection? http://bitsavers.trailing-edge.com/pdf/ibm/3279/SY33-0069-3_3279_Color_Disp… According to the above manual the frame sync is 10 ms for model 2 and 13.8 ms for model 3 (this is a model 3). And moreover if 20Hz is the frequency used for generating the vertical it could explain why the fuse blew since the current in the deflection yoke should normally increase linearly with time. Three times longer deflection period would yield a three time higher current, thus very likely to exceed the 1.5A rating of the fuse. So I am looking for either another analogue board for an IBM 3279 or a schematic for the thing or maybe both would be great. IBM stuff is annoyingly hard to repair... Has anyone seen schematics for the IBM 3279? Does anyone have a spare analogue board? /Mattis

4 years

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by jnc＠mercury.lcs.mit.edu

> From: Chris Zach > Might have an older MXV11 as well, could the 18 bit one do this Ooh, good catch; yes, the MXV11-A also has an LTC. I too have an 'extra' one. The OP should probably check to see if his P/S generates the bus clock signal; most of the options we've discussed for him would need it. Noel

4 years

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by cmhanson＠eschatologist.net

My little LSI-11 system doesn't have a usable Line-Time Clock because it lacks the register, which it expects to be in either an MXV11-B (M7195) or a BDV11 (M8012). My power supply theoretically supplies the LTC but I haven't confirmed that, so my preference would be an M7195 if possible. Does anyone have one they'd be interested in parting with? I'm fine with shipping internationally and with paying a reasonable price, and I promise to take good care of it and pass it on to another good home if I should ever part with it. (Friends don't let friends recycle rare electronics.) Alternately, is there a "modern" Q-bus board that provides things like LTC (both the clock and the register), SLU, memory, etc.? -- Chris

4 years

Concurrent Controls Multiuser DOS

by new_castle_j＠yahoo.com

I'm researching Multiuser DOS out of my own interest. A version made by Concurrent Controls specifically. However, I have been unable to find documentation on it to satisfy my curiosity on how it works and how it is configured. They must have somehow broken the 640K barrier or virtualized each user session, I'd like to understand it better. What were it's limitations, I'm guessing that each user didn't get direct access to hardware. Anyone out there have a document or experience with it? Thanks, Jonathan

4 years

Compaq Portable II PSU - value of C13?

by jules.richardson99＠gmail.com

Hi all, Does anyone happen to know the value of C13 in a Compaq Portable II power supply? It's a small-ish tantalum that lives next to the heatsink between U6 and U7 - although mine doesn't live any more, having just roasted itself in spectacular fashion. Quite possibly there's some other fault at play, but on the other hand it may have just been its time; tantalums in vintage stuff seem a little prone to failure. cheers Jules

4 years

Pro 350 Print Set

by robert.jarratt＠ntlworld.com

Manx lists MP-01394-00 as the Field Maintenance Print Set for the DEC Professional 350. I can't find this online and I was wondering if anyone has a scan of it by any chance? Thanks Rob

4 years

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test-drb October 2020