test-drb

test-drb@ccmp.vtda.org

101090 discussions

by robert.jarratt＠ntlworld.com

I have another PSU I have been meaning to look at for a long time. This one has fairly high output ripple and some of the voltages do not appear to be where they should be. I have checked all the capacitors for ESR and they appear to be OK, with the exception of the two big smoothing capacitors on the primary side. One of them appears to be slightly bulging, but has low-ish ESR, the other has a much higher ESR. Is it possible that these capacitors could be the cause of the out-of-spec outputs? Thanks Rob

6 years, 3 months

VAXmate PSU fixed, but no video

by robert.jarratt＠ntlworld.com

Some of you may recall seeing me post about the VAXmate PSU failure. Thanks to members of this list I found the failed part in the PSU and the PSU is now working again. However, it looks like the PSU failed because of a failure on the monitor board. There is a burning smell coming from it, possibly the flyback transformer, but I am not 100% sure. I don't see physical damage, but of course that doesn't mean there isn't a problem. When I took the monitor board out again after this, I wasn't sure if the EHT lead was making good contact with the CRT anode. The monitor board is described in section 4.4 of this document: http://bitsavers.org/pdf/dec/vaxmate/EK-PC500-TD_VAXmate_Technical_Descripti on_1987.pdf I need some advice on diagnosing the problem, I have a few questions: 1. If the EHT lead was not properly connected to the CRT anode, could that cause problems? 2. Is there anything I can safely do with a bench power supply to isolate the problem? 3. Any other suggestions for diagnosing the problem? 4. There is an outline spec of the flyback transformer in the section 4.4.3.2 of the VAXmate technical description, what chance of finding a "modern" replacement? I have posted about the PSU repair here: https://robs-old-computers.com/2020/04/18/vaxmate-h7270-psu-fixed-but-no-vid eo/ Thanks Rob

6 years, 3 months

Looking for a document regarding PDP8

by len＠shustek.com

At 10:00 AM 4/17/2020, Bob Smith <bobsmithofd at gmail.com> wrote: >...I believe sometime in the late 70s, maybe as late as 1980, a prof >associated with UMass wrote a paper describing an extension of the >PDP8 called 8/X or 8X. >...I believe, my memory is fuzzy, that it was a prof nnmed Stone or >Stoner (perhaps Harold S) who lead the effort and had his name on the >paper. That is probably Harold S. Stone, whom I knew as a Stanford prof in the early 1970s and did some corporate consulting with. Brilliant guy. From 1974 to 1984 he was at UMass Amherst, so your memory isn't fuzzy at all. He also worked at the IBM Yorktown Heights research center. He was the author of several books and many papers about computer architecture, algorithms, and interfaces. Unfortunately I don't remember him working on a PDP-8 extension, and a quick search of the ACM Digital Library turned up nothing. As far as I know he's still alive at the age of 82.

6 years, 3 months

DEC QBUS Backplanes

by bill.gunshannon＠hotmail.com

I have been sorting thru a bunch of stuff in an effort to clean the place up (Aren't we all doing that now with all this time on our hands?) I found a backplane. It says Digital on it but does not have an H- number. I also don;t find it listed in any of the lists I can find on the web. It has 8 A-B slots and 4 C-D slots. the Four C-D are on the bottom half of the backplane. I am assuming it is 18 bit and the C-D were intended for things like the 2 board RL controller. Anybody familiar with this and able to identify it? Anybody interested in it? It should fit in a USPS Medium Flat Rate Box. bill

6 years, 3 months

Fwd: ROLM CBX 8000 System Service Manual Vol. 2 Scans Released!

by rgalliett＠surewest.net

Hello. I have both, Rolm CBX System Service Manuals l and ll as well as a Release 8/8001 Student Maintenance Course binder. Are you interested in these??Thank youSent from my LG Phoenix 3, an AT&T 4G LTE smartphone

6 years, 3 months

Scanning incomplete and updated documents

by aperry＠snowmoose.com

I recently received a bunch of hardware/software documents to scan. I am only roughly familiar with the systems covered by the docs. I have encountered a couple situations that I would like guidance on. 1. One document is a software installation manual in a loose leaf binder with other documents. It has a title page, tables of contents, etc., several chapters, and then it gets interesting. It has several appendix sections (starting at A), an index, then more appendix sections (starting at A as well), and then another index. The document title and its font match of the second set of appendix sections and second index matches the table of contents and chapters. The first set of appendix sections and index are a little different. The topics covered in the sets of appendix sections are not the same. Should I create two different pdfs with different appendix sections or create a single pdf with both sets? 2. One document is missing the title page and table of contents. Should the pdf just be what I have or should I create those pages for the pdf? Thanks, alan

6 years, 3 months

ICL1501 Cobol manual available

by jos.dreesen＠greenmail.ch

Since you are all talking COBOL now : ftp://ftp.dreesen.ch/ICL1501 There is the manual for the early 70?s COBOL implementation for the ICL1501, a small 8K or 16K TTL based personal computer ( TTL based CPU, with 2x 74181 ALU and a 32x8 CRT display) Not the best of scans, but that alas reflects the material I have. Some other? doku on the ICL1501 is also included :? an operator guide and tape utilities user guide. I do have the tape with the COBOL itself, alas no way yet of gettig it on modern hardware. And if anyone has dokumentation on the ICl1503 or 1501/43, in particular the Diablo drive interface then I sure would like to see it ! Have the kontroller, but no documentation... Al, as always, feel free to add any and all to bitsavers. Jos

6 years, 3 months

anybody have MOVIE.BYU?

by rdawson16＠hotmail.com

The famous Brigham Young University 3D graphics program, by Dr. Hank Christensen. I am looking for the fortran source, it should be 7 files: DISPLAY SECTION UTILITY TITLE COMPOSE UPDATE MOSAIC Any docs related too. Thanks for letting me beg. Randy

6 years, 3 months

Core Memory Photo

by keith＠saracom.com

I have three others with the cover still on :) I want to make a clear plexiglass cover for them. Also have the driver boards. On 2020-04-15 13:00, cctech-request at classiccmp.org wrote: > Send cctech mailing list submissions to > cctech at classiccmp.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.classiccmp.org/mailman/listinfo/cctech > or, via email, send a message with subject or body 'help' to > cctech-request at classiccmp.org > > You can reach the person managing the list at > cctech-owner at classiccmp.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of cctech digest..." > > Today's Topics: > > 1. Re: Core Memory Photo (keith at saracom.com) > 2. Re: Core Memory Photo (Fred Cisin) > 3. Re: Core Memory Photo (Joshua Rice) > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 13 Apr 2020 13:05:03 -0400 > From: keith at saracom.com > To: cctech at classiccmp.org > Subject: Re: Core Memory Photo > Message-ID: <c39ba3b5e51779bd29b39938655c5a9c at saracom.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > "Ouch. Looks like that core took a serious hit." > > Yep it did. We ran the microscope into it at the lab. Ouch. Someone had > asked for a picture of core memory without the cover so I thought it > would do. > > ------------------------------ > > Message: 2 > Date: Tue, 14 Apr 2020 09:53:39 -0700 (PDT) > From: Fred Cisin <cisin at xenosoft.com> > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Subject: Re: Core Memory Photo > Message-ID: <Pine.LNX.4.64.2004140952460.8842 at shell.lmi.net> > Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed > > On Mon, 13 Apr 2020, keith--- via cctalk wrote: > >> "Ouch. Looks like that core took a serious hit." >> Yep it did. We ran the microscope into it at the lab. Ouch. Someone had >> asked for a picture of core memory without the cover so I thought it >> would do. > > It is beautiful! > > ------------------------------ > > Message: 3 > Date: Wed, 15 Apr 2020 10:09:38 +0100 > From: Joshua Rice <Rice43 at btinternet.com> > To: Fred Cisin <cisin at xenosoft.com>, "General Discussion: On-Topic and > Off-Topic Posts" <cctalk at classiccmp.org> > Subject: Re: Core Memory Photo > Message-ID: <353A7AE4-A147-4A06-9AFD-4A3398FABD1C at btinternet.com> > Content-Type: text/plain; charset=utf-8 > > Was beautiful. > > That?s pretty mangled now. > > On Apr 14, 2020, at 5:53 PM, Fred Cisin via cctalk <cctalk at classiccmp.org> wrote: > > On Mon, 13 Apr 2020, keith--- via cctalk wrote: "Ouch. Looks like that core took a serious hit." Yep it did. We ran the microscope into it at the lab. Ouch. Someone had > asked for a picture of core memory without the cover so I thought it > would do. > It is beautiful! End of cctech Digest, Vol 67, Issue 15 **************************************

6 years, 3 months

State of New Jersey needs COBOL programmers

by jeffrey＠vcfed.org

https://josephsteinberg.com/covid-19-response-new-jersey-urgently-needs-cob… -- ========================================= Jeff Brace Vice President & Board Member, VCF East Showrunner Vintage Computer Federation http://www.vcfed.org/ jeffrey at vcfed.org

6 years, 3 months

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