test-drb April 2019

test-drb@ccmp.vtda.org

134 participants
129 discussions

by sales＠elecplus.com

I talked to a recycler today, who said he told his workers to throw out 2000 Model F keyboards last week, but he doubts they did it. I also asked him about 8088, 2086, and 386 computers. He said they go straight to the grinder. I told him I will buy them. Then an HP dealer contacted me, wants to know if I buy old HP stuff. I told him Apollo and earlier. Let me know if there is something specific HP you want. Cindy Croxton Electronics Plus 1613 Water Street Kerrville, TX 78028 830-370-3239 cell sales at elecplus.com --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

5 years, 3 months

PDP-8: count number of set bits in a word

by kylevowen＠gmail.com

Just wondering if anyone has come up with a fast way to count the number of 1s in a word on a PDP-8. The obvious way is looping 12 times, rotating the word through the link or sign bit, incrementing a count based on the value of the link or sign. With a small lookup table, you can reduce the total number of loops by counting multiple groups of bits at a time, but this of course comes with the cost of using more memory. Any other suggestions? Much appreciated, Kyle

5 years, 3 months

PDP-8: count number of set bits in a word

by guykd＠optusnet.com.au

At 08:49 PM 5/04/2019 +0000, you wrote: >Hi Kyle, > >hat's a really interesting problem, and the government (NSA) wanted this badly and done FAST. > >they asked Seymour Cray to create a specific instruction for this and they called it 'population count' > >Anybody know the why and how it is useful? > >I am deep in matrix math books and 'classification algorithms' in statistics math, looking into electronics reliability WCCA, so this is an interesting topic. > >Randy If we're considering hardware solutions, then the best way is to build a simple I/O device, with a writeable latch for the data word, fed as address into some nonvolatile memory like a big EPROM or flash, the output of which can be read via a port. Fill the NV memory with the required lookup table (derived by some code written in anything. BASIC for lols.) So the required code is just one write and one read. See the size chart: https://en.wikipedia.org/wiki/EPROM The biggest EPROM made was ST M27C322, 32 Mbit, 2Mx16. 21 Address bits, 16 data bits, 80nS access time. http://pdf.datasheetcatalog.com/datasheet/stmicroelectronics/6184.pdf Wasteful though, since the result only needs 5 bits. For an 8 bit result, 27C4001, 512K x 8 bit, 19 Address bits. http://www-inst.eecs.berkeley.edu/~cs150/fa02/docs/M27C4001.pdf If the argument is only a 16bit word, then use a 27512. 64K x 8 bit Guy

5 years, 3 months

Yes there is a PDP 10 front panel and Kenbak on Ebay

by mark＠matlockfamily.com

Subject: Re: Yes there is a PDP 10 front panel and Kenbak on Ebay > > From: Guy Dunphy > > > What I want to know is, how do front panels of historic computers so > > often get separated from the rest of the computer? > The other thing that happened on PDP-11/70s was that if your system was maintained by DEC, the field service group would want to install the KY11-RE Remote Serial Console Control which replaced the beautiful front panel with a more or less blank panel with only a key switch. It let DEC dial in and run diagnostics, and the Blinkin' Light panel was set aside often in the collection of someone. However the blank panel still needs the bezel for a good display of it. So unfortunately, there are more console panels than bezels which often did not get salvaged at the time the PDP-11/70 was taken out of service. Mark M.

5 years, 3 months

Yes there is a PDP 10 front panel and Kenbak on Ebay

by jnc＠mercury.lcs.mit.edu

> From: Al Kossow > because it's $125 lower than the last one that sold. > https://www.ebay.com/itm/113190860596 Wow - somebody got a real deal! Looks like the seller listed it as a BiN with a low (for what it was) price; bet they're kicking themselves now, seeing what this one is going for, that they didn't go the auction route. Noel

5 years, 3 months

FTGH - Compaq laptop LTE 5280

by Richard.Sheppard＠telus.com

Worked last time powered (no guarantees), with expansion dock. Free for pickup only in Toronto, Canada. Richard Sheppard

5 years, 3 months

Retaining file-modified timestamps

by jnc＠mercury.lcs.mit.edu

The following, which I just sent to TUHS, might be of intererest to some here. Noel ---- So, a while back I mentioned that I'd done tweaked versions of 'cp', 'mv', 'chmod' etc for V6 which retained the original modified date of a file (when the actual contents were not changed). I had some requests for those versions, which I have finally got around to checking and uploading (along with 'mvall', which for some reason V6 didn't have). I've added them to a couple of my V6 pages: http://www.chiappa.net/~jnc/tech/V6Unix.html#mvall http://www.chiappa.net/~jnc/tech/ImprovingV6.html#FileWrite Note (per the page) that the latter group all require the smdate() system call, which was commented out in 'vanilla' V6 (because using it confused the backup system); the page gives instructions on how to turn it back on.

5 years, 3 months

Yes there is a PDP 10 front panel and Kenbak on Ebay

by billdegnan＠gmail.com

Yes there is a PDP 10 front panel and Kenbak on Ebay and no, a "best offer" of $250 for the front panel will not be accepted. :-) Bill

5 years, 3 months

H786 power supply help wanted

by charlesmorris800＠centurytel.net

I have a PDP-11/23+ and the power supply (H786) "last ran when parked" a year or so ago. But there's no DC output at all today, and the fans are running so there is AC power... I also have the original H7861 that came with it, which had a blown chopper transistor. I couldn't find anything else bad, so I replaced the transistor and within a few seconds of running, it blew again. :( So I need some help - I've never been good at fixing switching supplies, not to mention the high-side hazards. The simplest solution would be just to replace it with a working unit. Anyone got one to sell, hopefully cheap? :) If not, can anyone fix one or both of mine? thanks! Charles

5 years, 3 months

Yes there is a PDP 10 front panel and Kenbak on Ebay

by couryhouse＠aol.com

any? relation? to? marlys nelson? at? river falls? Ed#In a message dated 4/3/2019 12:40:06 PM US Mountain Standard Time, cctalk at classiccmp.org writes: I mean that semi-sarcastically as this list probably knows better already. =] -- Anders Nelson +1 (517) 775-6129 www.erogear.com On Wed, Apr 3, 2019 at 3:37 PM Anders Nelson <anders.k.nelson at gmail.com> wrote: > My god people, stop bidding! There are 6 days left. > -- > Anders Nelson > > +1 (517) 775-6129 > > www.erogear.com > > > On Wed, Apr 3, 2019 at 2:51 PM Bill Degnan via cctalk < > cctalk at classiccmp.org> wrote: > >> Yes there is a PDP 10 front panel and? Kenbak on Ebay >> >> and no, a "best offer" of $250 for the front panel will not be accepted. >> :-) >> >> Bill >> >

5 years, 3 months

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test-drb April 2019