- cctalk - classiccmp.org

by Christian Corti

It seems that nowadays you can't get *any* replacement for failing DEC 3639 aka 2N3639 transistors. All parts are obsolete and unobtanium, e.g. 2N3640, PN3640, MMBT3640 and so on. So, what can be used instead? The most important electrical parameter is the storage time. It needs to be *very* low, around 20-30 ns. Does it mean that a failing PDP-8 will stay a dead PDP-8 from now on? Christian

10 hours, 38 minutes

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Looking for a bootloader

by Peter Ekstrom

I am looking for the assembler listing for a bootloader for booting from MSCP disks like RD-disks. Google has not been very helpful and my assembler knowledge is not enough for me to write one from scratch. Does anyone have one they can share? - Peter

23 hours, 42 minutes

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Friden edge punched cards

by Paul Koning

I was just looking at some Friden Flexowriter documentation, specifically the later 2300 series. They look somewhat more modern than the well known Flexowriters but seem to be comparable otherwise. I remember seeing a mix in the TU Eindhoven computer center, around 1970. The documentation mentions an optional feature, the ability to read and punch "edge punched cards". Those look like conventional Hollerith cards, but instead of the 12 row punching with rectangular holes, they are punched along the bottom edge in exactly the same manner as an 8 channel punched tape. In other words, imagine running a blank card through the tape path of a paper tape punch, and that's what you would see. I never ran into this before. Has anyone ever seen these in the wild? paul

2 days, 10 hours

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Suggestions for Repairing a Keyboard Retaining Lug

by Rob Jarratt

I have an ANK 2462 keyboard for my Olivetti M24. The lugs on a couple of the retaining clips for the keyboard enclosure have broken off and disappeared. In fact, the keyboard came to me with tape holding it together! I guess I can live with using tape to hold it together, but it would be nice if I could fix this. I am looking for clever suggestions for how to replace the lugs. Any good ideas? The existing lugs look like this: https://1drv.ms/f/c/fc758a5a91b91301/Es7R00Lwr6lHosNt3JZlX20BXGTxi5N1SkYkl9K 0QAko3g?e=r1UnbI Thanks Rob

3 days, 9 hours

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Author of tar for v7 Unix?

by Zane Healy

Does anyone happen to know who the author is of tar for v7 Unix? I have a friend who is trying to figure that out? Zane

3 days, 22 hours

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Gimix hardware, MFM Hard Drive & 8" Double Side Drives

by Mike Katz

I just purchased an old Gimix computer (now if only I can get it from Orlando to Chicago before my friend goes down there for Christmas). It has an OMTI 20C-1 MFM hard disk controller with a IMI 5018 19MB hard disk drive in it. It has been recommended that i don't even turn the system on with the hard drive in it but rather I remove the drive an I send the IMI 18MB drive directly to a recovery house for data recovery. What do you all think about that? Do any of you have any experience with a recovery service for MFM ST-506 Drives? Also, does anyone have a half height 30MB or larger MFM ST-506 compatible drive that will work with the OMTI 20C controller for sale at a reasonable price. Preferably one that at least spins up. Also, does anyone have the syquest 5MB removable MFM drive and some cartridges, also at a reasonable price. My goal is to equip the Gimix with the following drives: * 2 80 Track DS/DD 5 1/4" half high floppy drives (in the system) * 2 77 Track DS/DD 8" Floppies (I have these in need of cleaning up, just not in a Gimix case) * 1 18 to 50MB MFM half high MFM Hard Drive (system has a full high 18MB drive) * 1 6MB Syquest removable cartridge drive half high (I need to find) At some point I would love to expand the RAM to as close to 1MB as I can (CPU/Motherboard supports up to 1016KB) and add a 3 or 4 port intelligent serial card and an intelligent parallel card (I'm sure these cards are unobtanium). Thank you all for your help If you have a dual 8" drive setup (double sided drives, and enclosure) that you need a good home for, please let me know. I'm in the Chicago Area. Thanks, Mike bitwiz(a)12bitsbest.com

4 days

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Looking for my old MicroVAX-II

by Richard Cini

All – This is kind of a crazy request, but many years ago (20+ years), I gave away my MicroVAX-II to someone on the list. I can’t find any of the original emails, but I remember it was in a BA23 tower and included an external table-top drive enclosure with, I think, an RD54 in it. It ran Ultrix, but I can’t remember exactly which version. I’ve floated in-and-out of DEC over the years, and honestly, I’m kind of sorry I gave it away (like so many other systems I had over the years). I had gotten it in a haul from Temple University in the late-1990’s. Anyway, I’d love to get another one. So, if someone is looking to re-home a MicroVAX-II, keep me in mind. Thanks! Rich -- Rich Cini http://cini.classiccmp.org https://github.com/RichCini

4 days, 1 hour

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Re: How hard would it be to make new dec tape media?

by Bob Vines

> > ---------- Forwarded message ---------- > From: Paul Koning <paulkoning(a)comcast.net> > To: "cctalk(a)classiccmp.org" <cctalk(a)classiccmp.org> > Cc: > Bcc: > Date: Sun, 2 Nov 2025 14:43:49 -0500 > Subject: [cctalk] Re: How hard would it be to make new dec tape media? > > > > On Nov 2, 2025, at 10:46 AM, Jon Elson via cctalk <cctalk(a)classiccmp.org> > wrote: > > > > On 11/1/25 20:49, ben via cctalk wrote: > >> How hard would it be to make new dec tape media? > >> 60 year tape could use a replacement. > >> Ben. > >> > > DecTape is laminated, ie. it has Mylar on both sides of the oxide. 50 > years ago, we made working replacements from 3/4" instrumentation tape, but > it was NOT laminated. It had a print-through issue where if left sitting > for a few months, it would start getting errors. I have no idea if there > is anywhere you can buy 3/4" instrumentation tape. Maybe you can get 3/4" > video tape. > > Bitsavers has the 3M spec for 480 and 481 sandwich tape, I'm not sure > which of these two is what DEC used. It seems crazy, but it can't hurt to > ask 3M if they still make that stuff. > > paul 10-20 years ago I had a good Point-of-Contact (POC) at 3M (before we both retired). I asked him whether they still (at that time) made DECtape media and was told that 3M had sold their magnetic media operations to another company who also got out of the business before I contacted them. I also asked my POC (and the contact at the other company) if any DECtape media had been kept in a warehouse or similar -- he checked 3M's inventory system and told me that they had no record of any remaining DECtape media. The other company's contact had a similar "you've struck out" story. Bob P.S. I thought that I read here or in a PDP-8-specific forum/mail-list that DECtape wasn't actually laminated on both sides, which apparently explained the visible red oxide material removed from dirty DECtapes while cleaning them (per whoever posted their observations)?

4 days, 3 hours

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Re: Looking for an IF-20 interface for an Brother AX-45 typewriter. Saw this today. I was checking for other parts....

by Cliff Stage

I have one IF20 if you are interested.may work still, had allowed printing and disc storage for 2 × novels and and drafts. My only issue is probably the print head on the CE50 typewriter_ printer head needs replacement, but "modem" is ok I bet. Stagecliff(a)gmail.com

4 days, 6 hours

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Is Ansgar Kückes on this list, or can someone put me in touch with him?

by bradmcook2013＠gmail.com

Hi all, Sorry to crash your party, but I'm doing research for a book and was hoping to connect with Ansgar Kückes, who owns this site about old school HP computers: https://www.hp9845.net/ Is he on this list? Or does someone know how to reach him? The contact methods on his site don't work anymore. Thanks. Brad

4 days, 16 hours

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