test-drb February 2015

test-drb@ccmp.vtda.org

203 participants
261 discussions

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

by jnc＠mercury.lcs.mit.edu

> From: Noel Chiappa > (I suspect, but have yet to verify, that this is in part because bus > grant lines are run directly from that slot to the UNIBUS adapter slot.) So it turns out I was half-wrong, but half-right. I was paging through a copy of EK-PDP84-TM-PR4 (PDP-11/84 Technical Manual) which I recently acquired: in section 2.1.14 "Backplane (H9277-A)", pg. 2-6, the following sentence appears: Bus signals BDMGI (pin AR2) and BIAKI (pin AM2) for slots 2 & 3 are jumpered on the front of the backplane. (This is not in any other version of EK-PDP84-TM, of which I have several.) So I got out my spare 11/84 backplane, and sure enough there are two jumpers, W1 and W2. The traces connected to them are, luckily, on the surface, so it's possible to see where they go: one end runs to a trace connected from slot 1 to slot 2, and the other to a trace connected from slot 3 to slot 4. EK-PDP84-TM-PR2 actually contains (pp. D-4 to D-8) prints for the backplane. Unfortunately, they are very low-res, and only partially readable, but one can see, on the bottom of the first print (D-4), the two jumpers. The associated traces do indeed connect to AM2 (BIAKI), AN2 (BIAKO), AR2 (BDMGI) and AS2 (BDMGO). In other words, when the jumpers are in, the CPU's BIAKO/BDMGO pins are connected directly to the UNIBUS adapter's BIAKI/BDMGI pins; when they are out, those signals are routed through the two 'memory' slots, in the normal QBUS manner. What this strongly suggests to me is that those two slots _can_ function as real QBUS slots. Otherwise, why arrange so that the grant lines can run through them? I haven't examined all the other pins, to make sure they contain the full set of QBUS signals - in part because I don't want to pore over those poor images! (Speaking of which, does anyone have a copy of either 11/84 Field Maintainance Print Set - MP-01955 or MP-02536? Neither one seems to be online - at least, as best I can tell, from some Googling, although others may have better Google-fu than me - and it would be fabulous to have access to them.) But I do strongly suspect they can function that way; at some point, when I have an /84 running, I'll actually try them out. As to why DEC put this capability in, and then didn't document it or use it - who knows? Maybe they though it would introduce extra complixity in the user instructions, or something. Anyway, I think we are close to cracking this particular puzzle... Noel

11 years, 1 month

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

by jnc＠mercury.lcs.mit.edu

> From: Jerome H. Fine > With regard to the MSV11-JD in the PDP-11/84, was this board placed > after the KDJ11-AE board or before it? After. The CPU _has_ to go in slot 1 on the 11/84 backplane. (I suspect, but have yet to verify, that this is in part because bus grant lines are run directly from that slot to the UNIBUS adapter slot.) > Also, has anyone ever used a KDJ11-AC board with the 15 MHz crystal in > the PDP-11/84 backplane? I can't see why it should not work, but just > maybe the PDP-11/84 backplane and a simple KDJ11-AC board are not > compatible. Would a KDJ11-A board even work in an 11/84 backplane? It wouldn't (couldn't) do the special PMI (actually, we ought to distinguish between 'QBUS PMI', such as in the 11/83, and 'UNIBUS PMI', as in the 11/84; the second is a superset of the first, I believe) protocol, so it wouldn't work with the UNIBUS adapter. See also Micronote #39, "Differences between KDJ11-A and KDJ11-B". Noel

11 years, 1 month

Sharp PC-1600 keyboard issues

by derschjo＠gmail.com

Another day, another project (the DAP will wait until I have the wiring to support it...). This week a bunch of "Refurbished" Sharp PC-1600s showed up on eBay for cheap and I snagged one; it arrived this evening. It looks like the unit is effectively new-old-stock; it doesn't seem to have been used since Sharp refurbished it back in the day -- it arrived with the original Sharp-branded batteries in the compartment. Amazingly, only one of the four batteries leaked, but only a tiny bit and there's no obvious corrosion anywhere from it (whew). The PC-1600 powers on and mostly behaves normally after an "All Reset" but the keyboard is having trouble; here are the symptoms: - Keys A-K on the 2nd row of the QWERTY section do not function ('L' does). - The "Shift" key doesn't work properly -- hitting it doesn't cause the "Shift" annunciator on the LCD to light up. However, it does seem to do *something* in that if you hit Shift+another (working) key, nothing happens at all (for example, Shift+5 should result in a left curly brace but does nothing at all.). - The "SML" key does not put the machine in lowercase mode, instead one of the Kanji (i believe) annunciators gets toggled. This has no other obvious effect (uppercase letters are still produced from the working letter keys...) - Hitting the "KB II/Click" key (farthest right under the LCD) turns "Key Click" mode on even though Shift is not being depressed. (Or maybe this is normal behavior -- I can't find this key described in the manual...) Otherwise, the thing seems to be working OK, it'll calculate fine and I can enter/run small programs (that don't use the home row for entry...) I've found the Technical Drawing set here: http://www.sharp-pc-1600.de/Schaltpl%8ane%20A3/Technical_Drawing_DINA3.pdf which makes it obvious that the dead home-row keys are related to the KIN3 line from the keyboard matrix; I note that the keyboard signals are brought to the edge of the PCB and connected to a membrane layer which contains additional circuitry, including what looks to be an IC that does the keyboard decoding. My first guess would be dirty contact between the PCB and this membrane (esp. since the lines in question are close to a hole in the battery compartment where the aforementioned 30-year-old batteries were...) but I'm a bit nervous to disassemble and clean this without knowing how it's held together. Anyone have any experience here? Any tips? Thanks as always, Josh

11 years, 1 month

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

by jnc＠mercury.lcs.mit.edu

> From: Henk Gooijen > Maybe a few PALs have to be a faster version, but I do not expect that. > The 15 MHz to 18 MHz is not that big of a difference. I did wonder about that, but they boards use parts from a number of different chip companies (both the PALs, and the PROMs), so since I don't know how to read those parts for speed variants, I couldn't say. > From: Johnny Billquist > The 11/84 variant is pretty much a PMI bus all the way, but I seem to > remember a couple of signals defined differently even in the 11/84 > compared to the 11/83. If you run across where you saw that, I'd be curious. The 84's use is, as you point out, different, since it includes the CPU<->UNIBUS adapter protocol for UNIBUS cycles. But I would have assumed that it was a plain superset of the 83's (not that I have read much about 11/83's... :-). > From: Jerome H. Fine > The MSV11-JB (1 MB) and MSV11-JC (2 MB) are used in the PDP-11/84. The > MSV11-JD (1 MB) and the MSV11-JE (2 MB) are used in the PDP-11/83. Err, not sure this is correct: I got an 11/84 with an MSV11-JD in it. As someone pointed out in a later message, the difference between the B/C and D/E is that the B/C only work as PMI memories, their QBUS functionality has some issues (IIRC, something to do with QBUS block transfers not working correctly). > In addition, for at least the PDP-11/83, the PMI memory must be placed > into the backplane ahead of the CPU for the memory to function as PMI > memory. That may be the only position allowed for the memory for the > PDP-11/84. The 11/84 backplane has two special Q22/CD slots after the processor slot which the memory goes in, with the CD sections wired to through-connect the PMI pins. I have this sneaking suspicion that the Q22 portions of those two slots aren't _real_ QBUS slots (so you can't plug a QBUS device into them if you aren't using them for memory :-), because I suspect they didn't run BIAK and BDMG to those slots, but rather piped them directly to the UNIBUS adapter slot. My reasoning for that is that if you don't plug in a memory card in one of those slots, you don't have to plug in a grant continuity card, so.... Anyway, I have a spare 11/84 backplane, and one day I'll get around to poking at it with an ohmmeter to verify that suspicion. > I seem to remember that when two memory boards are used, they should be > the same. Really? That would surprise me. Noel

11 years, 1 month

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

by jhfinedp3k＠compsys.to

Does anyone know why DEC would have MSV11-JC boards for use ONLY with a PDP-11/84 and the MSV11-JE boards which could be used with BOTH the PDP-11/83 and the PDP-11/84? It seems inconsistent. >Glen Slick wrote: >>On Wed, Feb 4, 2015 at 7:09 PM, Jerome H. Fine <jhfinedp3k at compsys.to> wrote: > > >>Longer explanation: The PMI memory used in the PDP-11/84 is sufficiently >>different >>from the PMI memory used in the PDP-11/83 that the magic smoke might be >>released >>if the incorrect PMI memory is used. The MSV11-JB (1 MB) and MSV11-JC (2 >>MB) >>are used in the PDP-11/84. The MSV11-JD (1 MB) and the MSV11-JE (2 MB) are >>used in the PDP-11/83. >> >The MSV11-JD and MSV11-JE are documented as being compatible with both >the PDP-11/84 and Q-bus systems. The documented restriction is that >the MSV11-JB and MSV11-JC are only compatible with PDP-11/84 systems >and incompatible with Q-bus systems. > >http://www.bitsavers.org/pdf/dec/qbus/oemMicronotes.pdf > >uNote # 028 >MSV11-Q/M/J MEMORY COMPARISONS > >MSV11-J >------- >The MSV11-J has four versions, the MSV11-JB and the MSV11-JC which are >used in the PDP-11/84 UNIBUS systems and the MSV11-JD and the MSV11-JE >are used in either the MicroPDP-11/83 Q-bus systems, or the PDP-11/84 >UNIBUS systems. All four modules use ECC memory for error correction, >as well as using 256K bit MOS RAM parts on either a half for fully >populated quad size module. > >NOTE: >----- >NONE OF THE FOUR MSV11-J MODULES CAN BE PLACED IN A Q/Q BACKPLANE >SLOT. IF THIS IS ATTEMPTED PERMANENT DAMAGE WILL BE DONE TO THE BOARDS >AND TO THE SYSTEM. > >The MSV11-JB (M8637-BA) is a half populated quad size PMI memory >module containing 1MB of memory. The second version of the MSV11-J is >the MSV11-JC (M8637-CA), this is a fully populated MSV11-JB quad size >PMI memory module containing 2MB of memory. These two module can not >be used in a Q-bus system due to gate array incompatibilities, and can >only be used in the PDP-11/84 systems which use the UNIBUS/PMI bus >interface (KTJ11-A). The third version of the MSV11-J is the MSV11-JD >(M8637-DA) which is a half populated quad size PMI memory module >containing 1MB of memory. The last version of the MSV11-J is the >MSV11-JE, (M8637-EA) which is a fully populated MSV11-JD quad size PMI >memory module containing 2MB of memory. These last two modules can be >used with either the MicroPDP-11/83 system which uses the Q-bus/PMI >bus interface or the PDP-11/84 system which was mentioned above. > >Although the MSV11-JD and MSV11-JE are PMI memories they can be used >in two other Q-bus configurations. >(more details follow...) > THANK YOU for the correction. After 20 years, the memory becomes a bit hazy. Also, I have only the 2 boards which are both 2 MB, so there must have been some confusion when I was told that a 1 MB and a 2 MB board should not be combined. It is good to know that is also not true. Does anyone know why DEC would have both MSV11-JC boards for use only with a PDP-11/84 and MSV11-JE boards which could be used with both the PDP-11/83 and the PDP-11/84? I have never worked much with Unibus systems and never with a PDP-11/84. Also, thank you for confirming that these memory boards MUST NOT be used in a Q/Q backplane. At one point, the MSV11-JE memory boards were equally priced with other 2 MB Qbus memory boards since most individuals thought they could be used only as PMI memory. I have no idea what the current prices are. Jerome Fine

11 years, 1 month

When to re-condition electrolytics

by jnc＠mercury.lcs.mit.edu

So, I'm about to bring up an old 11/10, and step a) is going to be getting the power supply up. So this means probably reconditioning some old electrolytics. So my question is 'should I _always_ recondition old caps, or is there some way to tell if they are still OK'? E.g. if they check out OK on an ohmmeter (no dead shorts), and also on a ESR meter, does that mean they are good to go? Or should I just always recondition them? I ask because this power supply (H750) seems to be a switching supply, and so I can't use the simple VARIAC hack, I'm going to have to do each capacitor individually. (For you experienced hardware guys, this is probably No Big Deal, but I'm mildly terrified... :-) Noel

11 years, 1 month

RA-81 issues (Jerry Wright)

by michael.99.thompson＠gmail.com

> > From: Jerry Wright > Sent: Friday, February 06, 2015 8:54 PM > Subject: RA-81 issues > > I have a rack full of RA81's, all Pass Rom base self test. If I try to > spin > up one of the drives, It will start to spin up and then just stop. There > are > no front panel lights that come on or codes on the terminal screen. all 3 > drives do the same. > > These are not connected to a controller, and the manual does not say this > is need. > > The forth one has no drive and the motor seems to turn hard, is there a > brake > on the motor ??? > > - what I'm I missing here > Thanks Jerry > I have seen two common problems problems with RA-81 drives. Failure of the motor start capacitor, and failure of the optical sensor on the bottom of the HDA for spindle speed. With both failures the drive will start to spin-up, and then spin-down. You can connect a serial terminal emulator to the DB25 diag connector. Then you can run internal diagnostics and get the fault codes. The RICM has several RA-81 drives, all with failed optical sensors. -- Michael Thompson

11 years, 1 month

11/23 clock issue

by jnc＠mercury.lcs.mit.edu

> From: Brent Hilpert >> Well, try removing W1 to isolate the output of the xtal oscillator E15 >> from inverter input pin E4.4. Sigh, the crystal output is dead as a doornail. Total flat-line. Guess I'm going to have to find a new one... I actually think there's an open in there, because the input to the buffer inverter stays at +2V, whether the crystal is connected or not. If there was some sort of internal short in the crystal taking its output to ground, I'd have expected it to pull the inverter's input down. > TP4 looks to be an 'input' test point, rather than an output. The > pull-down resistor value (150 or 180 ohms) has been selected such that > it is low enough to allow enough current to flow through the tri-state > control input E4.1 to pull it low normally, but high enough to allow > one to connect TP4 high, to enter tri-state Ah, got it. (I tended to assume test points were outputs, but I need to remember that they may be inputs.) > What the point of going to tri-state is, is not clear, considering that > W1 is there for an external clock. A conjecture is there may have been > some external test fixture that tri-stated it for some sort of > synchronous single-step clocking. Yeah, but couldn't they have lifted the W1 jumper, and fed their test clock in that way? Eh, not important. > Could also check the V reading on the open E4.4 input. See above - +2V is a floating TTL input, ISTR? > From: Holm Tiffe > Hmm, may be since his hints are standard debugging technique and you > aren't really familiar with debugging?? I cheerfully admit to being primarily a software person. But I have been debugging broken hardware off and on for 30+ years - although not as a principal occupation, of course. I think it's more just that my mind does not do hardware intuitively (the more-so, the further one gets from the ideal - aka digital at the design level - to real hardware) - I have to think about it. > You don't ned no pullup for +5. All open TTL inputs are reading High > w/o any pullup. That's why all those boards use pullups on unused inputs that need to be 1, right? :-) But you're probably correct for a quick test. Noel

11 years, 1 month

seeking quality tape recorder

by dave＠661.org

I'm looking for a decent quality portable tape recorder. I do want recording ability so I can make new tapes for my C64 among other purposes. I was about to purchase an Ion Tape Express Plus, but was told by Silent700 in #classiccmp that his imposes an abnoxious throbbing noise to the audio. Does anyone have any different experiences with that unit? Can you recommend something good other than the Ion one? -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

11 years, 1 month

Stupid AC wiring question (220-ish Volts...)

by jnc＠mercury.lcs.mit.edu

> From: Josh Dersch > Luckily heavy items can be wheeled on a hand-cart around to the back of > the house, where there's direct access to the basement; no tricky > stairs to deal with. O lucky man! My basement is only stairs-accessible (although one of them is an outside stairs, which is a big help), which led to an extremely annoying incident recently. (This has nothing to do with wiring, but your comment poked a hot-button...) I already had one 11/84, which was donated to me by a fellow aficionado of PDP-11's out in Wisconsin. When I got it here, I was trying to work out how to get it all (CPU cabinet, TU80 cabinet, RA81 cabinet [no drives], and 2 RA81's [separate]) into the basement (the only feasible place to put it in our establishment). I wound up building a ramp out of 2x10's on the outside stairs, and using a block+tackle to lower the units down that into the basement. Worked pretty well, actually - got the whole works down by myself in a couple of hours. So I got another 11/84 system (yeah, yeah, I know) which was in Fornicalia, and had to have it shipped. I originally tried to ship it freight (hey, the units are on wheels, and I didn't care if it got dinged a bit through not being packaged), but when they found out it wasn't palletized, I had to go 'white glove' (at twice the cost). But the good part was 'at least' with WG you get 'inside delivery'. So I'm figuring, good, they'll help me get it into the basement. Nothing doing. I showed them the units in the basement (so they'd know I had experience doing it), they looked at the ramp, and they called their company and then flat-out refused to have anything to do with the process. They claimed they thought it was 'dangerous'. I suspect their real motivation was i) it was raining lightly (which is another irritating thing, they were orignally scheduled to deliver on a day when it was supposed to be good weather, and they begged to move the delivery up, and I told them about the weather, but they were insistent, so I agreed - big mistake, I should have dug in my heels), and ii) they were in a hurry (see previous about wanting to deliver a day early) and wanted to hit the road ASAP. So anyway, we stuck it all in the garage to wait for a day it wasn't raining (hey, if I had to do it all myself, why do it in the rain?), and then my wife and I (she's 4' 10", and all of like 90 lbs) got it into the basement in a couple of hours, no problem. But two big, burly moving guys (I'm 6'0", 200 lbs, and they were a lot bigger than me) thought it was too much for them. To add final insult to injury, the moving company refused to offer any partial refund for not providing the 'inside delivery' they had been paid (a lot!) for! In addition to all the above, it took them 6 weeks to get the stuff here from California. Now, admittedly, Christmas and New Year's were in there, but... Anyway, I would highly recommend having nothing to do with this company; it was an outfit called UKAY. I've dealt with a number of crappy shippers, but these guys were The Shipping Company From Hell. Tell everyone you know about them. Noel

11 years, 1 month

← Newer
1
...
18
19
20
21
22
23
24
...
27
Older →

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 February 2015