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    Western Europe Silent 700 or similar small terminal sought

    A friend of mine in London would like to enter the old computer hobby by means of having a hard-copy terminal. The frustrations that can accompany this particular selection give us all hope that he'll enjoy a speedy recovery from his new retro interest and will soon be pursuing more wholesome...
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    SOS! Tektronix 4006-1 terminal on the fritz right before the show!

    Hi folks! I have five days (full of regular job) to repair a just-failed Tektronix 4006-1 vector graphics terminal before next weekend's Retro Computer Festival at the Centre for Computing History in Cambridge. Far enough off that we can try to fix it but soon enough for it to be stressful! I...
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    Tek 4051: Tape drive way out of calibration

    I have two Tektronix 4051s, and neither has DC200 tape cartridge drives in perfect health. On the first, the drive sounds like it's been built out of flagpole pulleys and pepper grinders. I assume I can service the transport motor etc. with some porpoise jaw oil (or some sewing machine oil if I...
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    Resetting a Tektronix 4051

    I'm debugging a Tektronix 4051 with a hardware fault somewhere. It would be convenient to be able to reset the machine without power-cycling it. What would be the best way to do this: pulling RESTART-0 to 0V? (For now: address and data lines are behaving normally, but something appears to be...
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    Tektronix 4054A Calibration (with Option 31)

    At long last a friend and I have started to undertake the 4054A calibration procedure (PDF page 99-138). There is a lot of detail, but we find that certain parts are unclear or even obviously wrong. The most outstanding example of this is the mislabeling of the standard and Option 31 HV boards...
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    CGA Mode 4 colours --- working on CGA, failing on EGA?

    I've swapped my (IBM original) CGA card for an (IBM) EGA card in my 5170. It's set up to drive a 5153 for now --- the 5154 still needs fixing. A while ago I wrote my first x86 assembly program, which does a bit of CGA graphics in Mode 4 (and also Mode 5). The code successfully sets the Mode 4...
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    5170 power supply (ASTEC AA13240) power-on spike bug

    The rapid, helpful response to my 5154 question (thanks @modem7 !) has encouraged me to ask about the other power supply thing vexing my 5170 these days :) It's not too pressing because I can use an adapted ATX PSU, but I'd like to restore the original PSU that came in my IBM 5170. There were...
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    5154 Monitor PSU: Capacitors for 200-240VAC

    The patient is an IBM 5154 display that has been recapped by someone who used no-name parts. The voltage ratings on the "new" post-rectification DC smoothing caps (the two big ones) seem suspiciously low for the rectified AC mains, and anyway one of them is quite bulged. I'd like to replace the...
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    I wrote a (subset-of-)Pascal compiler for Tektronix 4050 BASIC

    The Tektronix 4050-series machines are incredible, but I just don't want to write code in BASIC. Structured programming was a pretty good idea. I'm not allergic to GOTOs, but I prefer my jumps to remain in assembly language. So I wrote a compiler. Now I can program in a reasonably spacious...
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    Northern Europe [UK] Junk drawer PC-AT bits (drive rail, ISA slot covers)

    Hi folks, I'm looking for a few things for my PC-AT that might be accumulating in a junk drawer or rattling around in a box near you: Metal ISA slot covers, nothing special about them at all. I need a couple of these. Additionally, one (1) compatible screw would be nice to have. IBM PC AT...
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    Tektronix 4054A HoLLyWoOD Syndrome

    Hi folks, I have a Tek 4054A whose beam occasionally wanders and jumps around. This yields a phenomenon I call "Hollywood Syndrome" because letters you type as the beam is sliding about look abut as tidy as the Hollywood Sign. This video shows the effect well: You can really see the cursor...
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    How did computers in the '70s avoid frying DRAM chips?

    I think this is a fairly basic electronics question. If you read datasheets for old DRAMs that used multiple power supplies, you'll find warnings like these: That's "Forward biasing this supply (that's Vbb) with respect to Vss will destroy the memory device". You'll also find instructions...
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    1970s IBM 24-pin ribbon cable connector

    Posting to "Minis and Mainframes" because I'm guessing that most 1970s IBM fans hang out here. I'm looking for plug and socket components for a system of 24-pin connectors that IBM used for ribbon-cable interconnect in the 1970s. Here is a diagram of such a connector: And here are some...
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    A modern Linux hates (bridging) vintage BSD! Any old Ethernet experts know why?

    We all knew the rivalry was real! (Heck, netcraft confirmed it!) (old joke) For months I've been connecting my mid-1980s 4.2BSD box (one of these) to the Internet (in a very limited way!) through a Raspberry Pi (acting as an Ethernet bridge) and an Amazon AWS host. This has allowed me to serve...
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    Sick IBM 5100 DC300 tape cartridges --- plan of attack?

    A few weeks ago I took a chance on eBay for some IBM Problem Solver Library tapes for the IBM 5100. They've arrived, and after replacing the tension bands with the Mobilon bands that have been described elsewhere in this forum, it appears that they're in an unsurprising condition for 44-year-old...
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    Old computers serving HTTP

    After two months of rest and recuperation, our Whitechapel MG-1 is back to serving HTTP requests again at http://mg-1.uk:31132. This is not a dependable computer at all and it will probably be down again by the time you read this. It did make me curious: do other people have old machines...
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    Seeking BrouHaHa Smalltalk

    I'm searching for an old Smalltalk implementation from the mid-'80s called "BrouHaHa". A paper about it is browseable online here: https://www.researchgate.net/publication/221321630_BrouHaHa-_A_Portable_Smalltalk_Interpreter I'm interested in running it on a Whitechapel MG-1, but the paper...
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    What's it like to boot 42nix on a NS32016-powered Whitechapel Computer Works MG-1?

    Like this! https://www.youtube.com/watch?v=JMQ9EvZLSos Nothing too exciting to watch---a fairly standard 4.2BSD startup and a pre-X11 monochrome graphical environment---but perhaps still interesting to some!
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    WTB: Three button bus mouse (UK/EU preferred)

    Hi all, It's been fun using an old one-button Mac mouse on our old Whitechapel box, but having to use the tactile switches we kludged into our adapter for the two extra buttons is getting a bit tedious. Does anyone have an old three-button Logitech (or no-name compatible) bus mouse lying...
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    help, TCP wizards! 4.2BSD vs Linux congestion control?

    Greetings all, I'm trying to copy some files from a 4.2BSD machine (a Whitechapel MG-1 running 42nix 2.5, for what it's worth) over ethernet via good old-fashioned rsh. I'm encountering a strange problem: the first ten packets seem to transfer fine, but subsequent packets are increasingly...
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