test-drb April 2020

test-drb@ccmp.vtda.org

142 participants
114 discussions

by bbortnick＠2bcool.ca

Old IBM magnetic media Yes, two cartridges have a total capacity of 100mb, the same as the staging disks, IBM 3330-1. However, the entire cartridge contents are not staged, only the cylinders that have the requested data. Not sure why your cartridges were empty. Here?s a link to my ?working ? 3850 mass storage robotic arm for your viewing pleasure! *https://www.youtube.com/watch?v=V8ifNxDgxuY&pbjreload=10* <https://www.youtube.com/watch?v=V8ifNxDgxuY&pbjreload=10> ?\_(?)_/?

4 years, 8 months

pdp11/84 PMI memory: What is the problem with Q bus?

by cz＠alembic.crystel.com

So I picked up an 11/84 CPU, 3mb of memory, and a 11/84 Unibus card on Ebay. Goal is to speed up my fastest 11 here For boot time, the diagnostics run in 13 seconds (from when it starts to prompt) on the 11/73 board I have and 13 seconds on the 11/84 board. This is with a camintonn 2mb half height memory board. Put in the first PMI module above the 11/84 CPU and tried it out. This is a CA rev board which apparently only works in a Unibus pdp11 and not a Q-bus one. Apparently it does work. So what exactly was the bug with the older PMI memory? Block mode DMA, I'm using an MTI ESDI controller which can do 16 word block DMA on Q Bus. Something else? Here's the output from RT11. .show all RT-11FB (S) V05.05 Booted from DU6:RT11FB USR is set SWAP EXIT is set SWAP KMON is set NOIND TT is set NOQUIET ERROR is set ERROR SL is set OFF EDIT is set KED FORTRAN is set FORTRA KMON nesting depth is 3 Global .SCCA flag is disabled PDP 11/83 Processor 2048KB of memory Floating Point Accelerator Unit Extended Instruction Set (EIS) Memory Management Unit ECC Memory Cache Memory PMI Memory 60 Cycle System Clock Device I/O time-out support Error logging support Memory parity support System job support Global .SCCA support FPU support Extended unit support Device Status CSR Vector(s) ------ ------ --- --------- EL Not installed 000000 000 LD Installed 000000 000 BA Installed 000000 000 DY Not installed 177170 264 VM Installed 177572 250 SP Installed 000000 110 XL Not installed 176500 300 304 DL Installed 174400 160 MS Not installed 172522 224 DU Resident 172150 154 LS Not installed 176510 310 314 NL Installed 000000 000 TT (Resident) DU (Resident) DU6 = DK , SY MQ (Resident) LD DL VM SP BA NL 9 free slots Job Name Console Level State Low High Impure --- ---- ------- ----- ----- --- ---- ------ 0 RESORC 0 0 Run 000000 103232 105046 No multi-terminal support Address Module Words ------- ------ ----- 160000 IOPAGE 4096. 132174 DU 5570. 103274 RMON 5856. 001000 ..BG.. 16990. LD0 is DU6:RTTST.DSK[6000.]

4 years, 8 months

Unusual Punched Cards

by cctalk＠emailtoilet.com

This card is shorter than 40 columns but I can't tell if it has been cut off or not. I only have 1 so I can't let it go. http://www.ibmjunkman.com/cards/?Holder=2551 <http://www.ibmjunkman.com/cards/?Holder=2551&Img=0> &Img=0 You can search on Style and select different ones.

4 years, 8 months

correction OK Looking to purchase "Sensicall" and the ATT Code-Com" bell system attachment that woukd allow deaf to tap morse over phone lines thanks Ed at SMECC

by couryhouse＠aol.com

OK Looking to purchase "Sensicall" and the ATT Code-Com" bell system attachment that woukd allow deaf to tap morse over phone lines? thanks? Ed? at? SMECC

4 years, 8 months

Looking to purchase CODE A PHONE bell system attachment that woukd allow,deaf to send morse code through bell system phone. Respond off list...... they would tap on litte finger pad . this,was,an attachment to a regular phone,set made in later 60s or 70s. Person on other end would see light flash I guess... drop us a line off list.

by couryhouse＠aol.com

Looking to purchase CODE A PHONE? bell system attachment that woukd allow,deaf to send morse code through bell system phone.? Respond off list...... they would tap on litte finger pad . this,was,an attachment to a regular phone,set made in later 60s or 70s. Person on other end would see light flash I guess... drop us a line off list.

4 years, 8 months

Unusual Punched Cards (Peter Van Peborgh)

by michael.99.thompson＠gmail.com

> > Guys, > > I have been collecting all types of computer punched cards for a few years > now. In the distant past I actually used them! > > I am desperately looking for two types I do not have been able to find a > sample of: > * Jacquard fabric/carpet loom cards. OK, not computer but the > ancestor, for completeness of the history. There may be several formats of > these. > > Something like this? http://www.ricomputermuseum.org/Home/interesting_computer_items/jacquard-lo… -- Michael Thompson

4 years, 8 months

Unusual Punched Cards

by peter＠vanpeborgh.eu

Guys, I have been collecting all types of computer punched cards for a few years now. In the distant past I actually used them! I am desperately looking for two types I do not have been able to find a sample of: * Jacquard fabric/carpet loom cards. OK, not computer but the ancestor, for completeness of the history. There may be several formats of these. * Original Hollerith card, 12 rows by 24 columns. Once again, this is a long shot. Well if you don't ask, you never get! Thank you for your interest. Peter

4 years, 8 months

Another Unrelated PSU Question

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

4 years, 8 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

4 years, 8 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.

4 years, 8 months

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test-drb April 2020