test-drb

test-drb@ccmp.vtda.org

101090 discussions

Start a nNew thread

11/23 clock issue

by jnc＠mercury.lcs.mit.edu

> From: Holm Tiffe > Hmm.. it looks to me as if the Board is missing the jumper W1 Err..... no. :-) Noel

11 years, 6 months

Incandescent lights [Re: It's time to restore the 11/45.]

by jnc＠mercury.lcs.mit.edu

> From: John Kaur > If anyone has worked up a led replacement for the '45, would be of > interest. The original incandescents are not easy to find 'Back in the day', there were LED replacements available - I have no idea who from. They looked just like the bulbs, but had the red glass. (We replaced all the lights in our 11/45 with them.) Anyone know who/where/what they were? Or of a modern equivalent? Noel

11 years, 6 months

DEC fan silliness

by roeapeterson＠gmail.com

So I've got a BA11-N chassis (18-bit, 9xQ-cd slots) and the cardcage fan has failed. The damn thing is riveted in, I'm gonna have to drill. Strangely, the power supply fan has bolts/nuts. I've never seen DEC do something this silly before, but I'm sure there are stories out there...

11 years, 6 months

It's time to restore the 11/45.

by jacob.ritorto＠gmail.com

Hi, Having gotten the 11/34 rig up to a good spec, I'm sufficiently excited to tackle the 11/45. It's been powered off since 2004, when I briefly turned it on only to find a wild jumble of lights and that none of the front panel switches or knobs did anything to the lights. Couldn't get it to run or deposit values or *anything*. I therefore assumed it was badly broken and so left it until now. It has stayed perfectly high and dry but has gone to extremes in temperature as the storage isn't climate controlled (this is in western Pennsylvania). And there's a lot of dust. I'm not going for museum perfection, but want it to be very presentable (lobbying to keep it as my 'art' in the living room long term if it's presentable enough :) and functional. So I'm looking for tips on how to go about it? I was thinking: 1) Truck machine to living room, note positions of all wires / boards. Photograph, remove and clean dust from them. Place on antistatic bench. 2) Thoroughly blow out dust and debris, vacuum backplane and wipe down chassis and wires with damp cloth. 3) Map out desired hardware config: I have available two Fujitsu 160 disks, three Fujitsu M2333K disks and two Fujitsu M2372K disks. I need to decide how to rack and cable at least two, possibly up to four of them as the 8" ones have no mounting hardware. Operational status on all is "hopeful." I have two Emulex SC21s and an SC41 as well as an unmarked Xylogics Unibus SMD board. I'm also tempted to mount an RX02 drive as I have a controller and quite a mountain of floppies supposedly containing weird old stuff. I need to source an ethernet board and whatever cabling / bulkhead stuff follows. DZ11, its dist panel and a Diablo 630 printer would be nice, too. 4) This would also be a good time to broach the subject of whether or not the capacitors need special love, or if that just adds more risk of destroying something. Those familiar, please chime in as the archive is currently missing so I can't refer to the recent threads on this subject. Datapoint: I didn't mess at all with power supply / caps on my 11/34, which was stored right beside the '45 for the same timespan and it's running great now. Datapoint 2: with my amateur electronics skills / status, there's admittedly some risk just having me poking around in there, "learning" things :-\ Plus, I'm afraid of death from esoteric high voltages that I hear are present in these old power supplies. Is the 11/45 one of them? In a nutshell, this analog / power stuff is FAR FROM my forte; some hand-holding here would be most appreciated. 5) Insert an expendable Unibus module and power up; check & tune power. I need direction on how to go about this. Also, the bottom H742A power chassis isn't completely populated. Not sure if that's acceptable, on purpose or bad. 6) Reassemble, tidying up issues like missing / loose screws, rubbing cables, etc. along the way. 7) rt, 2.11BSD, rsx, rsts/e! (mostly via vtserver - I have a tu10 that I could get in on this deal, but its roller rubber has turned into goo and two cabinets in the living room is more than "pushing it." Later date on that puppy. ) Current module config starting from front of cabinet (yes, there are some gaps and M9200 jumpers I don't mention, too): M9301 + M787 M8114 M8115 M8112 M8113 M8100 M8101 M8102 M8103 M8104 M8105 M8106 M8108 M8107 M8109 M8110 g401 M7800 + M9200 jumper H214 G231 G110 H214 G231 G110 H214 G231 G110 Unibus cable runs out to third party external memory chassis, "Monolithic Systems Corp" Type MO v11/PDP11 P/N 300-0058-000, which is three quarters populated. If this memory is broken, I'm planning to use an M7891 instead (is that OK?). No Unibus termination after that. Is that weird / bad? Does this current config seem sound? Is there a problem obvious just from this description that would account for the unresponsive front panel? Here's the power supply situation: There are two H742A power chassis. Top contains h744, h744, h744, h744, h745. Bottom contains H745, H746, open, H744, open. big thx! jake

11 years, 6 months

It's time to restore the 11/45.

by jnc＠mercury.lcs.mit.edu

> From: Jacob Ritorto > Should I eliminate all this fancy bipolar and core memory and just use > an m7891? PS: I forgot to mention: that board, IIRC, _has_ to go into a Modified UNIBUS slot. Plugging it into something that's _not_ MUD will, I am pretty sure, fry something. Do you have a backplane with has MUD slots to plug it into? I _think_ DD11-C's and DD11-D's have them. > From: tony duell > A plain Variac does not provide isolation from the mains so you are > actually now working on mains-connected circuitry (read : dangerous and > you can't clip a 'scope on it). I'm clearly a little slow this morning: why can't you use a 'scope on it? > From: Mouse > Perhaps fortunately, it appears that here, at least, incandescents > aren't completely banned, just vanilla 100W ones. In the US, 'vanilla' 75W bulbs are now also banned (and I think 60W's are headed that way, too); 'specialty' bulbs (not sure of the exact definition - think coloured, etc) of 75W and 100W are still allowed. (As are, ironically, plain 150W and 200W!) Noel

11 years, 6 months

Prime?

by bbrown＠harpercollege.edu

I've heard something about a prime emulator (to run primos, premix etc).. does anyone know any info on where it is and how to get ahold of it? Anyone know of any actual prime hardware out there? Thank you! -Bob

11 years, 6 months

Heathkit H-8 Tape Sound Files?

by nf6x＠nf6x.net

Do any of y'all know of any archived tapes for the Heathkit H-8 computer that are online as audio files that I could record onto tapes, as opposed to image files containing the decoded data for use with emulators? So far, I've only found the latter, but would like to find the former for use with a real H-8. -- Mark J. Blair, NF6X <nf6x at nf6x.net> http://www.nf6x.net/

11 years, 6 months

Differences between PDP-11/83-84 M8190-AB/AC and AD/AE CPU cards

by jnc＠mercury.lcs.mit.edu

So I've seen some references which say that the M8190-AB and -AC (w-o/w FPJ11 FPP chip) are 15 MHz "11/73" CPUs for QBUS use, and the M8190-AD and -AE (w-o/w FPJ11) are 18 MHz "11/83-84" CPUs for UNIBUS use (via the KTJ11-B convertor, of course). (Of course, the /83 is nominally QBUS, but let's ignore that for the moment... :-) (And I'm not even going to try to give the KDJ11- suffixes that go with these... :-) However, I'm wondering if this is correct... I have a CPU board out of a 11/84 (one owned by DEC, no less!) which says M8190-AB on the handles, but the clock crystal says "18.432", and it has a 57-19400-09 J11 chip, which seems to be the 18MHz version (the 15Mhz seems to be -04). Comparing it to a 'stock' -AB, this one seems to have the same 74S472 PROMs (6 along the lower left-hand edge), PALs (top center and lower left), etc. But they also match the ones on a 'stock' -AE, too! So clearly an -AB/AC _can_ be _upgraded_ to an -AD/-AE... but are there actually any differences between an -AB/AC and an -AD/-AE, other than the speed? I don't have my /84 up yet, so I can't plug a stock -AB in and see if it works, but I'm starting to get the impression that except for the speed of the J11 (and the crystal), and whether or not it came with the FPJ11, all four of these boards are otherwise identical. Whether it's a 73, 83 or 84 depends entirely on whether it has PMI memory and the KTJ11-B UNIBUS converter (and the correct backplane, for the latter, of course). Anyone have an confirmation one way or the other? Thanks! Noel

11 years, 6 months

11/23 clock issue

by jnc＠mercury.lcs.mit.edu

So I'm debugging a dead PDP-11/23 board (M8186). The first thing I check is the clock; specifically the output of the first stage buffer-inverter (pin 16 of E4, a 74S240, upper right corner of page 2 of the prints), which is distributed to a number of places. Nada. Totally flat-lined. So I checked the input (pin 4), and it's sitting at about 2V. Also flat-lined. This does not seem good... :-) So here's my question: what's the likely fault here? The only thing upstream of that gate is the 13MHz crystal itself. So the fault has to be either the crystal or the S240 (which seems to be some sort of octal 3-state inverting buffer). Any guesses as to which? As usual, thanks in advance for any help! Noel

11 years, 6 months

It's time to restore the 11/45.

by jnc＠mercury.lcs.mit.edu

> From: Jon Elson > there is no part of the EUT that is at neutral potential > From: tony duell > With most 'scopes one side of the input is grounded -- you have a > coaxial cable with the shield connected to the 'scope case and true > ground. Ah. That's the part I was missing! I (naively :-) assumed that the 'scope's whole input amplifier would be 'floating', and the input signal would be taken as referenced to the 'ground' on the probe, which could itself be floating. Clearly not! (I'll have to look at the manuals/prints for my 'scopes - Tektronix 465's - to see if they are this way. Anyone happen to know, offhand?) Thanks! > In most, if not all, countries, one side of the mains is connected to > ground too. Yes, in the US that's code; neutral (aka 'return') is usually tied to ground at the main panel. (Well, at least in the state I live in - technically I suspect that it's under state law, not Federal, but I would assume the states are all the same, the way they are with commercial law.) Noel

11 years, 6 months

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb