- cctalk - classiccmp.org

by Peter Ekstrom

Does anyone know if there is any programming information about the BDV11 card? I have disassembled the ROM files for it and I see they do various operations with the registers on the card, but it is not clear to me exactly what they are doing. - Peter

6 hours, 56 minutes

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Hot Video Shift Register on VT100

by Rob Jarratt

(sending again from a different email address as I don't think my first email got through, apologies if this is a duplicate) I have a VT100 that I was working on a while back and then set aside for a bit. I have started to look at it again. I have noticed that the Video Shift Register, a 74S299, gets very hot, I can smell the heat and the chip gets almost too hot to touch, reaching almost 40 celsius. I have a working VT102 for comparison and the same chip there does not get so hot (it reaches about 30 celsius). I have already tried replacing the chip, but the new one gets equally hot. I looked at the signals the chip is receiving and the one that stands out as different is the CLK input (pin 12). It looks like this: https://rjarratt.wordpress.com/wp-content/uploads/2024/04/vt100-74s299-clk-s ignal.png. On the VT102 it looks like this: https://rjarratt.wordpress.com/wp-content/uploads/2025/11/vt102-74s299-clk-s ignal.png. It is much spikier on the VT100 and I was told at one point that this could be the cause of the hot running for the chip. Is that a reasonable assumption? Assuming the spikes are the cause of the hot running. I am trying to see why there is a difference. I have noticed that on the VT102 there is a 68R resistor between the DC011 which produces the signal and the 74S299. You can see this as R86 in the VT101 printset https://bitsavers.org/pdf/dec/terminal/vt101/MP-01066-00C_VT101_Family_Field _Maintenance_Print_Set_Apr82.pdf (p47 of the PDF). The VT100 printset dated Feb 82 https://bitsavers.org/pdf/dec/terminal/vt100/MP00633_VT100_Schematic_Feb82.p df shows an inductor L8 being used (PDF p17), but my VT100 does not have this and so must be described by the March 80 printset https://bitsavers.org/pdf/dec/terminal/vt100/MP00633_VT100_Mar80.pdf (PDF p17). Could the absence of L8 explain the spikier DOT CLK signal and the hotter 74S299? Incidentally, I suspect that the flyback transformer on my VT100 has failed. If anyone has a flyback transformer going spare, especially in the UK, then I would love to hear from you. Thanks Rob

8 hours, 5 minutes

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Conductive material in rubber dome

by me＠scifidan.com

I just acquired a TRS-80 model 102, my first of that model. Everything is great other than three keys. The 2 keys works intermittently, q, and [ don't work. Having checked the schematic, the keys have no commonality on the circuit. Before I pull the cap off the switch, I know that the rubber dome inside has material on the inner part that meets with the silver contacts to complete the circuit. I'm told this material will wear out or lose conductivity. I reflowed the solder joints on the pcb and this didn't help. Other people have simply replaced the rubber dome from another dead 102's keyboard. But, I'd rather attempt applying new material inside that dome. I'm hoping there is an inexpensive and mainstream solution I can buy at home depot or something. Any tips? Daniel sysop | Air & Wave BBS finger | calcmandan(a)bbs.erb.pw

8 hours, 32 minutes

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OCR and line printers

by Guy Fedorkow

Greetings Restorers, I think a number of us have wanted to restore software that's only available as a scanned listing from a line printer. The original printout probably wasn't the best typographic quality, and scanning doesn't improve it. As a first pass, OCR with tools like Adobe Acrobat can easily produce a rough draft of the content in text form, but it takes almost as much work to correct the many "typos" as it does to simply re-type the listing. It seems like, with all this high-tech AI processing around, it should be possible to take advantage of the limited character set, fixed fonts, and restricted grammar that one might find in a listing to resolve more of the ambiguities in character recognition. Does anyone have an approach that's more efficient than generic OCR and a long process of correcting typos on every line of code or comment? Thanks /guy

15 hours, 32 minutes

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OT Scotch Type 871 Tape Reel?

by Holm Tiffe

Hi all, I'm trying to sell an old Scotch tape reel on Ebay Kleinanzeigen here in germany. It's box is labeled 871-1-3600 R41 which I think means Type 871, 1 Inch and 3600 ft, Don't hve an idea about R41. Stock No: 84-9800-5294-2 I've bought that myself in a error..needed an Data tape to this time. Now one asks if that is an vintage video tape for the philisp EL3400 Recorder.. Has someone an idea what kind of tape that may be? Thx, Holm -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741

17 hours, 29 minutes

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VAX and OpenVMS

by Peter Ekstrom

Ok, started playing with the SIMH vax8600 simulator and OpenVMS 7.3 Hobbyist. I know they discontinued the hobbyist license program years ago, but does one actually need a license to run it? Or would an older version like 5.x or something be better? The OpenVMS community license is only for Alpha, Itanium and some x86_64 architectures so I'm sure that wouldn't work in a simulated VAX? - Peter

21 hours, 53 minutes

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Someone is letting go of a Data General Eclipse S/20 in Missouri

by Christian Liendo

This is not my ad, but I saw this and I figured someone would be interested and reach out. https://www.reddit.com/r/VintageComputers/comments/1oxu9h5/data_general_ecl…

2 days, 16 hours

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Ownership of microcomputing

by Murray McCullough

One of the greatest joys of classic computing was running what you wanted on your own computer. What has happened in the intervening years? Have ‘software walls’ created a computing environment that benefits software gate-keepers(owners of computing technology) by monopolizing creativity, freedom to program and establishing a defacto ‘true ownership’. Will the future be this or will it be more like the earliest years of microcomputing? Murray 🙂

3 days, 12 hours

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WINdows-1985

by Murray McCullough

According to history Windows 1 was introduced to the world on Nov. 20, 1985, 40 years ago, minus 2 days. Prior to this Windows was first announced in 1983(vaporware) but…An even earlier development was Interface Manager. What we have now is much more and ‘better’ but for classic computing I still prefer WIN 3.1. Happy computing. Murray 🙂

6 days, 13 hours

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Depraz Mouse, Type D 83 / P, Excellent Condition, Looking to Establish Value and Sell

by microprint314＠gmail.com

I found a Depraz mouse the other day (Type D 83 / P) while going through moving boxes. I used to - long time ago - make things out of broken or disassembled computer gear. There was the most amazing store in Dover, NJ called Second Byte where I spent too much time and money (according to my ex-wife). I purchased this mouse 30 years ago with no particular project in mind, and it has just stayed packed away. I'm looking to sell it but I admittedly don't know what it's worth. I see two of them on eBay for $20-$30K, but don't see any Sold Items as a reference. Those sale prices sound largely aspirational. The mouse is in pretty amazing physical condition, with only basic scuffing on the red surface. The larger spots you see are reflections. The cable has scuffs but no fraying at all. The ball turns when the mouse is rolled. No pins are bent on the connector (RS-232 / DB9?). The three buttons click. Any insight - or offers - is welcomed. Thanks.

1 week

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