test-drb

test-drb@ccmp.vtda.org

101090 discussions

by Tim＠Rikers.org

Someone on this list, I don't remember who, asked me if I was interested in this, and then dropped it off. I've not gotten around to doing anything with it, and I could use the space back. If anyone is interested, holler. HP 2250 Measurement & Control Processor Pictures are the same ones that came with it. Photographer unknown. https://photos.app.goo.gl/XjEj8E8vQ8KX9xcg8 If your interested in picking it up, email me directly, please. If you have more information to share, respond to the list. :) If anyone knows more about what this is, I'd be interested to hear. I got these links from Mike on the SIMH list: http://www.hpmuseum.net/display_item.php?hw=986 http://www.hpmuseum.net/document.php?hwfile=5124 http://www.hpmuseum.net/document.php?hwfile=4579 Mine is the "2250M" version. Apparently this heavy beast is "mobile" because it has wheels on it. :)

6 years, 12 months

Pinout for current loop interface

by charlesmorris800＠centurytel.net

>I've never heard of people using DB25 for 20mA, at least historically, contemporaneous with its widespread actual use. E.g. DEC universally used 'flat' 8-pin Mate-n-Lok connectors for 20mA serial connections. Thanks for the comments... I asked mostly because the ADM-3A has both RS-232 and current loop interfaces built-in (on the same female DB-25), selected by one of the DIP switches. I just hate having to make a custom cable for every terminal and computer I own or work with ;) -Charles --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 12 months

Archiving information, was Re: ADM-3A question

by jnc＠mercury.lcs.mit.edu

> From: Steven M Jones > imagine that a law is passed in a far away land, and the site owner > decides it's is too risky to bother with, and they then take the entire > site down - wiki and fora - with no warning and no access to the > material... > .. > I would strongly suggest that if people are going to do something of > the scale you describe, they might want to consider setting up a > distribution or replication mechanism Past events have made me very concerned about this issue! On a couple of occasions, Tore (who runs the CHWiki) has forgotten to pay the DNS fee, or something similar, and it went off-line (the first time for a week, as he was off camping). Leading to total panic on my part when he wasn't reachable, about all the content I'd written! There is an automatic backup system which sends copies to a machine at his house, so the particular scenario above (hosting sevice goes away with no warning) is not an issue. (Yes, a Chicxulub event in Scandanavia would defeat that, but we'd all probably have larger problems to worry about!) After the first event, I make manual backups here of all the articles I contribute. The biggest concern is if he has an unfortunate interaction with a truck. I did raise this issue with him, and he had some initial suggestions, but I haven't followed through. If people start contributing, it'd probably be time to formalize something. Noel

6 years, 12 months

Pinout for current loop interface

by jnc＠mercury.lcs.mit.edu

> From: Charles Morris > Is there any standard pinout for 20 ma current loop using a DB-25 > connector, analogous to the well-documents RS-232 serial interface? > ... > Or would you recommend I use a different connector entirely? .. Maybe a > Jones 4-pin would make more sense. I've never heard of people using DB25 for 20mA, at least historically, contemporaneous with its widespread actual use. E.g. DEC universally used 'flat' 8-pin Mate-n-Lok connectors for 20mA serial connections. Although I have the part numbers for both the male and female 8-pin shells, they are no longer in production, and are getting hard to find. Nothing precludes us from establishing a spec for 20mA via a DB25, of course - especially if a set of pins can be found whih will not cause damage if such a connector is plugged into an EIA connector by accident. As 'idiot proof' engineering, I'd be inclined to use some other connector (no suggestion from me as to what), but I can understand that people might prefer to use DB25 (which everyone has, and are easy to find). Noel

6 years, 12 months

VAX DATATRIEVE orange binders (4)

by toby＠telegraphics.com.au

Hi, I have four binders, pictured here: https://imgur.com/a/w9a3YEY * Reference Manual, AA-K079E-TE * Guide to Writing Reports, AA-P862C-TE * Handbook, AA-W675B-TE * User's Guide, AA-K080E-TE Did not see scans on bitsavers but it's possible I just overlooked them. Is there any interest in getting them scanned? I have a suitable scanner. I can also ship them (from Toronto, Canada) to anyone keen enough to pay shipping. --Toby

6 years, 12 months

Archiving information, was Re: ADM-3A question

by jnc＠mercury.lcs.mit.edu

> From: Seth J. Morabito >> having stuff scattered across a zillion personal pages (be they blogs, >> or whatever) is going to make it hard to find the useful one when >> needed > The sheer vastness of content available, combined with a Google > monoculture, combined with a concerted attempt to GAME the Google > monoculture, is making search and discovery hard An additional issue, I think, is that Google is deprecating sites that use HTTP, versus HTTPS. I can't comment more, lest I start ranting at the utter stupidity of forcing everyone to use HTTPS. But if those blogs are using HTTP, that will push them down the results. > I honestly don't know what to do about it. I don't have a better idea, > unless we go back to something like a directory-style curated > experience, a-la Yahoo! circa 1998-ish. I'm not sure that would scale to cover detailed pages on obsolete computers; why is a manual indexer going to cover them? Anyway, the whole 'how do we find the info' is a part of why I started working on CHWiki, once I discovered it - in addition to the usual advantages of wikis (good for collaboration, good for adding stuff incrementally), it would put all the info in one place, a 'one stop shopping' for old computer info. But when I tried to convince people to post stuff there, instead of on their blogs, I got at least one person who was pretty vehement that no way in h*** were they going to stop putting their stuff in their own blog. Noel

6 years, 12 months

Pinout for current loop interface

by charlesmorris800＠centurytel.net

Is there any standard pinout for 20 ma current loop using a DB-25 connector, analogous to the well-documents RS-232 serial interface? My PDP-8/A drives an ASR-33, and having just restored an ADM-3A I want to be able to unplug the TTY and plug in the ADM. I somewhat arbitrarily put the transmit data + on pin 2 and receive + on pin 3, and picked two uncommitted RS-232 pins for the - legs of both loops. The ADM-3A receives on pins 23 & 25, and transmits on pins 24 & 17. Polarity doesn't matter since both pairs use bridge rectifiers. If this is some kind of de facto standard, I'll change the bulkhead connector on the PDP-8 and the TTY to match. Otherwise I'll just make yet another unique cable to hook up the ADM-3A to the PDP-8 as it's wired. Or would you recommend I use a different connector entirely? The reason I used the DB-25 to begin with is that I had a DEC rack-mount plate that already takes one. Maybe a Jones 4-pin would make more sense. thanks for any tips. -Charles --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 12 months

GW-DEC-1: A New DEC Prototyping Board

by jnc＠mercury.lcs.mit.edu

> From: Brent Hilpert > I've seen pieces of HP high-end lab equipment from thru the 60s that > used tin plating on the PCB edge fingers, mating into gold-plated edge > connectors on the backplane. ISTR that DEC used bronze contacts in their backplanes, but basically all the boards had gold-plated fingers. (I think I've seen a few power supply boards that had tinned fingers.) I think the bronze was preferred since the contacts bend back and forth as cards are inserted/removed, and bronze is more durable; and being part tin, has the same corrosion characteristics are the tin. Noel

6 years, 12 months

RXV21 questions

by dj.taylor4＠comcast.net

I have 2 RXV21 RX02 controller boards.? They were bought to be used with the RX02 emulator, the one on github by AK6DN. Finally, I finished one of the emulator boards and tried it out on a PDP-11/03 and found that one of the RXV21? boards worked and the other didn't.? I assumed the one board was bad. Yesterday I tried the RX02 emulator in a BA23 with a 11/53 cpu (I also tried a 11/23+) cpu.? What I found is that the one that worked in the 11/03 didn't work, while the other board kinda worked.? I could do a DIRECTORY and DUMP from RT11, but I couldn't boot the RX02 in the microPDP-11. Today I ran into Chuck Dickman's web site that talked about the Etch versions of the board and which would work in a microPDP-11. He showed how to convert an Etch 'D' board to work in a microPDP-11. I have Etch 'C' - this is the one that works in the 11/03, and an Etch 'D'.? My 'D' board isn't exactly like the 'D' board he shows. What are the changes to the 'D' board that he outlines?? What is exactly the reason why the 'C' works in the 11/03 and why an 'F' or modified 'D' is needed for the microPDP-11? Doug

6 years, 12 months

ADM-3A question

by charlesmorris800＠centurytel.net

Today the replacement 'LS193 arrived, so I put it in the previously-installed socket and the screen is now 24x80 again :) I'd been testing with the dip switch in half-duplex mode... For final test, I put it in FDX, connected to my HP protocol analyzer, and what do you know, no serial data out. The 1488 RS-232 driver was blown (TTL-level data going to it, but the RS-232 line was stuck in spacing). Not an uncommon failure with static discharge and incorrect cable hookups... I destructively removed it, again installed a good dip socket, now waiting for THAT chip (a variety of other line drivers in my drawer, but not 1488/1489). Meanwhile I noted another slide switch S8 ("GT/LK") near the DB-25 connectors. It is not referenced anywhere in the documentation, nor in the schematics! The wiper of the switch also goes through a hex inverter to a 74LS32 chip, ALSO not in the schematic or circuit description. This signal originates at the flip-flop that generates KBLOCK\. Finally, input pin 10 of the removed 1488 is supposed to be tied to pin 9, with the RTS output on pin 8. But pin 10 goes In fact, the PCB artwork at the end of the tech manual shows no connections except +5 and ground to that chip (position C2 I think), and it doesn't show the slide switch either. This is likely something for the auto-tester that LSI used to check these boards on the production line, although I don't know if the extra circuitry was added or removed during production. Anyone have internal documents on this? I'm just curious since it only appears to affect the keyboard lock functions which I'm not using anyway. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

6 years, 12 months

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