test-drb June 2015

test-drb@ccmp.vtda.org

165 participants
285 discussions

Memory options for an HP 1000 (HP 21MX / 2112A)

by marc.verdiell＠gmail.com

My soon to arrive HP 2112 has a 2102A memory controller and 3x 2102A cards of 8k memory each. I suppose I could add more 2102As to fill it up the 5 remaining slots and bring it up to 64k. But the recently posted IO manual says it can support way more - up to 1.28M. I'm not sure yet how the HP 1000 memory works. Can I put larger (>8k) capacity HP 1000 memory boards in there to expand memory beyond 64k? Do I need to replace the memory controller with one that matches the larger capacity cards then? Marc

9 years, 5 months

UNIBUS extension card/cable sets

by jnc＠mercury.lcs.mit.edu

> From: Paul Koning >> Right, but the very similar QBUS does have terminations (of a sort - >> the rules for when you need terminations on QBUS extensions are so >> complex that I don't really grok them yet) 'in the middle' > That doesn't seem likely. ... the definition of 'termination' is > something that you learn in EE 101 and are unlikely to forget. I agree with your sentiments, _but_ all I know is that if you look at, e.g. the 1982 'microcomputers and memories' handbook, pg. 251, you'l see a three-backplane system, with terminations at the start _and_ end of the first backplane (and also at the end of the third backplane). I've seen other similar diagrams elsewhere, that's merely the first one I ran across in a quick search for this post. Like I said, I cheerfully admit that I don't really fully understand what's going on there in the analog domain, but I've seen this in more than one place in the DEC QBUS multi-backplane configuration instructions. Noel

9 years, 5 months

Transmission lines Was: UNIBUS extension card/cable sets

by jnc＠mercury.lcs.mit.edu

> From: John Wilson > I chose the digital version of EE as my major precisely because I knew > I'd flunk Fields and Waves. Transmission lines are black magic as far > as I'm concerned! I too have a hard time with analog in general, but transmission lines I seem to be OK with. The way I think about them is to model them as pipes, and the signal as a sound (single pulse) sent down the pipe. Proper termination is like a piece of cotton at the end of the pipe, it sucks up the sound and you don't get a reflection. If you just cap off the end of the pipe (i.e. no termination), the sound bounces, and you get an echo. So if you have a small un-terminated branch, part of the pulse bounces off the end, and comes back out, and then propogates both ways, so the original pulse gets a messy trailer tacked on the back of it. Etc, etc. I dunno how accurate this model of mine is, but it seems to work OK! :-) Noel

9 years, 5 months

organizing a trip to Cuba

by billdegnan＠gmail.com

http://millennialmainframer.com/2014/12/ibm-still-waiting-cuba-pay-mainfram… Who's up for it? B

9 years, 5 months

UNIBUS extension card/cable sets

by jnc＠mercury.lcs.mit.edu

> From: tony duell > There are 3 40 pin Berg headers, one row of each appears to be ground Ah, hadn't noticed that! But then again, I hadn't looked at them closely yet! :-) Yes, they do connect to ground - all the UNIBUS ground pins are ganged together, and connected to the A-row Berg pins on all 3 connectors. So every other wire on the 40-conductor flat cables should be ground - that's even better than the classic BC11A, where almost every other line is, from what I can see, simply left floating (which is better than nothing, but not as good as grounding them, is my understanding). >> I was wondering if maybe the M9015 was an M9014 with termination >> resistors, or something (the way the QBUS versions come with and with >> termination) > I would be very surprised. Unibus is normally terminated at the ends > and not in the middle. Right, but the very similar QBUS does have terminations (of a sort - the rules for when you need terminations on QBUS extensions are so complex that I don't really grok them yet) 'in the middle', so... I just couldn't find out _anything_ about M9015's, so I was just guessing in the dark. Real data gratefully received. > From: John Wilson > I was kind of assuming that there's some impedance-matching (etc.) > problem with using ribbon cables for more than one hop. Hmm. Well, I dunno; that may be beyond my (minimal :-) level of analog expertise. I would have assumed that it's the _change_ from one impedance level to another that's the issue (you can get a reflection off the junction), so whether one's using long or short cables between a pair of M9014's, it shouldn't be _that_ big a deal (modulo propagation delays, which _are_ an issue with length). Perhaps someone else can opine? But I hope we can do fairly long runs with the 40-conductor (aka BC05L-xx), that could save us when we run out of BC11A's, if that strange Flexprint flat white cable the BC11A uses is no longer available. Noel PS: From what I can see so far (done half the pins), the M9014 and M9042 do have an identical pinout on the Berg connectors.

9 years, 5 months

UNIBUS extension card/cable sets

by jnc＠mercury.lcs.mit.edu

> From: Alan Perry > FYI, in my 750, the UNIBUS expansion has a L0010 in the main cabinet > and a M9014 in the expansion cabinet. > From: tony duell > If it's any help I pulled an M9014 out of the Unibus Out slot of my > 11/730. There's currently an M9302 in there. Very interesting! Thanks for the data. This seems to indicate that the M9014 could function as either end of the cable. I was wondering if maybe the M9015 was an M9014 with termination resistors, or something (the way the QBUS versions come with and with termination), so I tried to find a picture of one, but... I can't even find a picture! Has anyone even seen an M9015? >> I see 'three' different kinds of 'UNIBUS to cables' cards listed: >> M9014 UNIBUS to 3 H854s >> M9015 3 H854s to UNIBUS >> M9031 UNIBUS to 3 3M cables for 11/74 >> M9042 UNIBUS to 3 H854, Dual So I have compared an M9014 and an M9042; the former is a 'normal' height dual module, the latter is a 'short' dual module. I suspect that they have the same pinout on the Berg headers; I tried a couple of UNIBUS signals, and they led to the same pin on the Bergs on the two different units. If and when I get energetic I will make a complete pinout list for the two units (I haven't been able to find any documentation on any of them online). Some day I'll even try joining a BA11 to an -11 with a pair of M9014's, and see if it does indeed work. Also, does anyone out there with an 11/70 know what the M9031 is used for? (I.e. does your system have one/more, and if so, where are they?) Noel

9 years, 5 months

cctalk Digest, Vol 12, Issue 5

by marc.verdiell＠gmail.com

Good info David. Thanks once more. ------------- "J. David Bryan" <jdbryan at acm.org> said: Subject: Re: HP 2113e Battery resistor >I might put NiMH batteries instead.... That may not be advisable, given the continuous constant-current trickle charger in the CPU power supply. The Panasonic "Nickel Metal Hydride Technical Handbook" recommends charging for no more than 10-20 hours, saying: "The overcharging of nickel-metal hydride batteries, even by trickle charging, causes a deterioration in the characteristics of the batteries. To prevent overcharging by trickle charging or any other charging method, the provision of a timer to regulate the total charging time is recommended." Panasonic's "Nickel Cadmium Batteries Technical Handbook," on the other hand, says explicitly that continuous trickle charging for Ni-Cds is a recommended charging method. -- Dave ------------

9 years, 5 months

George!

by COURYHOUSE＠aol.com

Great save! By the Way Evan I like the photo of that self contained Syston Donner Analogue computer in your book! Ed# _www.smecc.org_ (http://www.smecc.org) In a message dated 6/22/2015 1:01:29 P.M. US Mountain Standard Time, evan at snarc.net writes: Here's a new picture of "George" -- aka the Philbrick analog computer that MARCH rescued two months ago. It was used at M.I.T. from 1958-1970. http://snarc.net/george.jpg

9 years, 5 months

Strange DEC PC05 paper tape reader: doc for M705 needed

by j_hoppe＠t-online.de

Hi all, I could acquire *four* rotten PC05 Papertape Reader/Punches for PDP-11. I'm now restoring them. One of these is strange: Normally, the feed hole (between data hole 3 and 4) is used to clock in bits from the data holes. But this very special PC05 does not have a phototransistor for the feed hole, so the data clock signal must be generated by the stepper motor driver. Maybe it's a very old model: the READER CONTROL module is M705, not the usual M7050. And there's no doc for it. Does anybody has a FPMS with schematics for the M705 modul? Perhaps as part of some PDP-8 doc? Thanks, Joerg

9 years, 6 months

1990 Era computer room

by COURYHOUSE＠aol.com

hp drives yes... data printer no... correct name is data products and a neat printer if you were just printing the first 20 col zone I remember something about this model banging it out at 800 or 1000 lpm at full 80 col it was 300 LPM ( This was the first formal sale our computer company had was to sell a used one of these to a consultant / programmer that did stuff on apple II systems ... I t had one bad hammer coil and he moved it to col. 80 and swapped the good one into the mid field he used the thing for years... we were to later have one of these that came in with a HP 2000 system and it served us well until replaced by a 600 LPM Data Products line printer as we wanted to print wider than 80 col. OK another odd thing - note tapes but lack of tape drives. If only we could see what was in the rest of the room! Ed Sharpe archivist for SMECC _www.smecc.org_ (http://www.smecc.org) In a message dated 6/22/2015 1:49:38 P.M. US Mountain Standard Time, jws at jwsss.com writes: On 6/22/2015 9:16 AM, Douglas Taylor wrote: > I saw this newpaper photo on ebay, item 191606970872, where these 2 > big wigs are proudly standing in front of their computer system > looking over some printout. > > The actual computers in the picture don't look familiar to me, can > anyone ID them? > > Doug The printers look like Data Printer 80 column printers. Can't tell about the systems, but they appear to have what look like analog meters on the panels, which is interesting.

9 years, 6 months

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test-drb June 2015