- cctalk - classiccmp.org

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)?

5 months, 2 weeks

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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

5 months, 2 weeks

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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

5 months, 2 weeks

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Unreliable Rotary Potentiometer

by Rob Jarratt

I have the contrast control on the monitor of my Olivetti M24 which has become unreliable, you only need to touch it and the display will disappear completely. It doesn't look too hard to replace the rotary potentiometer, but I was wondering if there is any way to "repair" it to keep the original part. It looks like this: https://1drv.ms/i/c/fc758a5a91b91301/ESPGlbvW5wxGpXPC5kXfzVMBTUUW96GThzDMqZ_ i8jq7tA?e=Ehmo1T Thanks Rob

5 months, 3 weeks

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reading DECtape

by Guy Fedorkow

We may have a half a dozen DECtapes, probably from the PDP-6 era, perhaps with ITS with content... Is there anyone, preferably in the MIT vicinity, who might have a working DECtape drive and be willing to try to read the tapes? Thanks /guy fedorkow

5 months, 3 weeks

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Re: reading DECtape

by Guy Fedorkow

Martin, Michael, Thank you! We don't have possession of the tapes yet, but, assuming that happens, I'll try RICM to see if their machines are working again. /guy fedorkow On 11/1/2025 1:00 PM, cctalk-request(a)classiccmp.org wrote: > Date: Fri, 31 Oct 2025 13:22:48 -0700 > From: Martin Eberhard<mfeberhard(a)gmail.com> > Subject: [cctalk] Re: reading DECtape > To:cctalk@classiccmp.org > Message-ID:<57DE7487-B3FA-4200-8D10-ACB4A5353CCE(a)gmail.com> > Content-Type: text/plain; charset=utf-8 > > If you don't find a closer alternative, I have working DECtape drives on my PDP8e (in California), as well as software that allows me to upload an entire tape image as a binary file (via Xmodem protocol). > > I'd be available to do this sometime after November 11. > > Martin > > Typing mangled by iPhone > >> On Oct 31, 2025, at 10:53 AM, Guy Fedorkow via cctalk<cctalk(a)classiccmp.org> wrote: >> >> We may have a half a dozen DECtapes, probably from the PDP-6 era, perhaps with ITS with content... >> Is there anyone, preferably in the MIT vicinity, who might have a working DECtape drive and be willing to try to read the tapes? >> >> Thanks >> /guy fedorkow >> >> >>

5 months, 3 weeks

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PDP-8 EAE

by Christian Corti

Can someone tell me the frequency of the R405 module in slot PF36 for the EAE of the classic PDP-8? Should it be the same as the R405 processor clock? Christian

5 months, 3 weeks

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"How to fix a Terak" tape?

by John Foust

I was reading my own Terak web page, and remembering that I'd read Doug Gale's history of computing at Cornell: https://ecommons.cornell.edu/bitstream/handle/1813/36810/00_TheEarlyYearsOf… and it mentions (at page 3.23) a "how to repair a Terak" video they made there, and he claims it was distributed to other universities that were also using Teraks. Has anyone ever seen this tape? - John

5 months, 3 weeks

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Re: MFM Hard Drive & 8" Double Side Drives

by David Gesswein

> From: Jim Davis <jim.p.davis(a)gmail.com> > Subject: [cctalk] Re: MFM Hard Drive & 8" Double Side Drives > Was anything MFM or RLL with a removible cart build in the 80's-90's? > I never heard of such a thing, Carts were scsi early 90's Syquest and > others?... > Yup https://en.wikipedia.org/wiki/SyQuest_Technology The early ones were ST412 type interface > From: Doc Shipley <doc(a)vaxen.net> > > Pretty sure Mr Gesswein is on this list but I don't see him post often. > Anyway, he designed a very handy MFM drive emulator: > > https://www.pdp8online.com/mfm/mfm.shtml > Yup but try not to hawk my board. When they say they want a drive I don't suggest alternatives. I also get the digest so most questions have been answered before I see them. Thanks all for the kind words.

5 months, 4 weeks

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The transistor invention

by Murray McCullough

I had forgotten that 75 years ago, Oct. 3, 1950, the transistor was invented leading to integrated circuits making possible personal computers and the interest of our love of computing. Where would we be without Bardeen's, Brattain's and Shockley's invention? Happy computing, Murray 🙂

5 months, 4 weeks

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