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WTB: Compaq Portable 386

by nw＠retrocomputingtasmania.com

If anyone has one they want to offload I'd be keen to hear about it please. thanks.

10 years, 6 months

blog entry

by tonypf11＠gmail.com

Hello, 4 hours ago I posted an email concerning a huge amount of documentation that I have. I also included about 30 pictures. I can find no indication that this email was distributed. Is there a problem with this information? Was it received? Tony Pflum

10 years, 6 months

DEC H7140 (11/44) power supply revisions and general advice?

by ard＠p850ug1.demon.co.uk

> > Once again, I find myself in over my head debugging a power supply, this > time an H7140 from a PDP-11/44. Here's the skinny: That doesn't surprise me, the H7140 is one of the most complex PSUs you are likely to come across... > When power is applied (plugged in, breaker switch flipped to "On") the > relay does not click - based on my readings of the manuals this should > happen after the bias voltages are up to spec. I measure 308VDC on the > lugs on the top of the memory board, so that's at least something > working. Getting to other points to test voltages is a bit more > difficult, especially with those high voltages in the way, what a nice > design :). That 300-odd volts comes from rectified (or voltage-doubled) mains. The relay is part of the soft-start circuit, it should operate after the 'bias' PSU has started up (it shorts out a resistor in the mains input circuit). With no other load on the supply you will get the 300V with the resistor still in circuit. There are _3_ SMPSUs in that box. One for the logic, one for the memory and one (known as 'Bias' in the DEC documentation) to power the control circuits, PSU control logic, etc. The last one is a relatively conventional SMPSU, it sounds like it isn't working. It's nasty in that almost all the circuitry is on the mains side of the isolation barrier, and an isolating transformer is almost essential when working on it. The chopper transformer is on the PSIU baseboard, the chopper transistor and much of the control circuity is on the 'Bias/Interface' PCB (leftmost board in the PSU box). Be warned, therefore that some circuitry on this board is not isolated >from the mains. I would start by seeing if the 12V (and 5V?) from the 'Bias supply' are missing. -tony

10 years, 6 months

blog entry

by COURYHOUSE＠aol.com

dunno did not see it Tony - - maybe file to large? send to me direct to check out thanks ed Sharpe archivist for smecc In a message dated 10/11/2015 6:13:45 P.M. US Mountain Standard Time, tonypf11 at gmail.com writes: Hello, 4 hours ago I posted an email concerning a huge amount of documentation that I have. I also included about 30 pictures. I can find no indication that this email was distributed. Is there a problem with this information? Was it received? Tony Pflum

10 years, 6 months

FS: Cray J932SE system

by ethan＠757.org

If anyone knows anyone looking for a Cray, Cray J932SE system. 32 proc, 2 megawords of RAM as I recall. Has VME IO subsystem, HIPPI channels on a lot of the CPU boards (originally was 4 x J932SE in a hypercube via hippi IIRC.) Has 4 SCSI disks (9GB) although has room for lots more (system checks disk firmware vendor.) I like it but no place to keep it and I don't want to keep moving it between rental house garages. It's currently in Norfolk Virginia, I'm in Northern Virginia. I have pics of it. I'm not sure the Unicos build I have is compatible with it, it kernel panics on startup. I have some software, the SWS Sparcstation 5. Uses 3 x 220v outlets @ 30 amps each. Here is some stuff from last time I played with it: https://users.757.org/~ethan/pics/geek/cray/ These are RARE. I think I know of two or three J932SE systems in the wild, one in Germany one in another foreign country. Was looking for $8500 or so. Pound for pound such a better deal than an Altair. -- Ethan O'Toole

10 years, 6 months

HP & 800BPI / was Re: Tape cleaner on eBay

by marc.verdiell＠gmail.com

Brent Hilpert <hilpert at cs.ubc.ca> wore: >I had that problem with the stuck reel hubs. Failed to take my own advice-to-self to leave the reels unmounted and they stuck again, >although easier to get off this time as it hadn't been many years under pressure. I ended up covering the rubber hub with black electrical tape. That prevents it from sticking again. >I had originally written it in a re-targetable cross-assembler in a now-outdated development environment under MacOS9. > Last year rewrote someone else's assembler (C source) - it should work in any standard C environment. > Was using it to re-assemble HPBASIC. > [...] Can send you the source if you wish. I'll gladly take the source, that would be very helpful later on. Marc

10 years, 6 months

Dead PET4032

by binarydinosaurs＠gmail.com

Hi folks, Some storage reorganisation last week uncovered a PET4032 I'd forgotten I had. Spotless internally (I remembered why later) and glass fuse intact so I attempted powerup. Nothing. No screen and no chirrup. Google + schematics time. I've checked AC voltage at the iron lump and all major chips + DRAM are getting the right voltages. The processor is generating a clock signal at PHI2 (~2.7V), I've checked continuity of all address and data lines for ROMs/processor/VIA/PIA. I can't check the contents of the Kernal ROM since it's not socketed and my track record of successfully removing big chips whole isn't good. One chip that does get hot is the Character Generator at UA3 which I was going to swap with the one in my other 4032, but that doesn't power up either. Presumably I can borrow one from a 3032 or 8096? A lot of the repair pages use a piggyback 6502/ROM/RAM add-in called a PETvet but all I have is a DMM, logic tester and other working PETs as sources of chips I can borrow. Are there any more steps I can try before checking ROM contents becomes necessary? Cheers. -- adrian/witchy Owner of Binary Dinosaurs, the UK's biggest home computer collection? www.binarydinosaurs.co.uk

10 years, 6 months

Symbolics MCD-405 tape drive / Georgens Industries

by aek＠bitsavers.org

Does anyone have a loose 3M/Georgens MCD-405 tape drive they could take board pictures and firmware dumps from, or any of the other MCD-40 series tape drives? I'm trying to figure out how similar it is to the one in the Apple 40mb tape drive. I was asked about recovering some tapes from a Supermac 40mb tape/disk scsi box, and I am trying to figure out what tape drive I might need to do it. It appears it is Gammamat format, which would work with the Apple drives, and I wanted to compare the firmware from a non-Apple, so I started looking around for SCSI Gammamat drives. I also thought this would be useful knowledge for anyone trying to dump Symbolics XL-Series DC2040 tapes. One interesting thing mentioned in the Amiga BTNTape tape handler was they mention it was possible on some MCD series drives to format a blank DC2000 tape. They mention formatting with 2:1 interleave. Sadly, there were also people who said there was a tech manual available from Georgens on the series, but they didn't want to spend $50 for it. Georgens Industries was in San Diego and there still a few traces of them, but they are long gone at their last adr. I see that Chuck mentioned they were into the maintenance biz, Georgens was involved with DEI down there looking at his patents, and bought 3M's streamer tape line. Places like Weird Stuff have piles of the DC2000 floppy tape drives, need to do more digging to see if there are any SCSI ones around. Then, I have to redo the pinch roller. All the Apple tape drives have been dead for over ten years with rollers turned to orange goo.

10 years, 6 months

UNIBUS RAM with Parity vs. None

by billdegnan＠gmail.com

(cross posted to MARCH list) Question about UNIBUS RAM with Parity vs. None I assembled a pdp 11/05 in a BK11-K box with a sticky 5 light - I can load an address, but the 5 light will erroneously (often but not always) light when I examine. Once 5 is turned on it stays on, even if the toggle switch is down. Once this occurs I cannot deposit nor can I examine contents of RAM. I intend to test the front panel to verify that toggle 5 is ok electrically, this is a to-do. The power checks out including DC LO AC LO. I transplanted the CPU cards into another system to test and they work also. Aside from the console itself, it must be a RAM problem. The system has 8K Core G235 (xy drive module) H217D (memory stack) G114 (sense / inhibit) M8293 (memory control module) My question - I have read, and to the best of my understanding believe I can swap an H217D with an H217C in this box. Anyone disagree, and if so why did DEC want their 11/05 S to use "D" model core (D=parity) and not C (C=no parity)? The PDP 11/40 I have uses C. -- Bill

10 years, 6 months

DEC H7140 (11/40) power supply revisions and general advice?

by derschjo＠gmail.com

Hey all -- Once again, I find myself in over my head debugging a power supply, this time an H7140 from a PDP-11/44. Here's the skinny: I examined the supply physically before experimenting and found a capacitor on the Bias/Interface board that was leaking, bursting and rather burned-out looking (not a great sign) -- this is capacitor C4 in the printsets on Bitsavers (http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp11/1144/MP00897_11X…) Everything else looked OK physically; I replaced the obviously bad capacitor at C4. When power is applied (plugged in, breaker switch flipped to "On") the relay does not click - based on my readings of the manuals this should happen after the bias voltages are up to spec. I measure 308VDC on the lugs on the top of the memory board, so that's at least something working. Getting to other points to test voltages is a bit more difficult, especially with those high voltages in the way, what a nice design :). Switching the front panel switch to "Local" (or any other position) has no effect -- no fans, no LEDs, nothing. I've double-checked all the wiring and everything looks OK. Capacitor C4 looks to be involved with the START-UP DRIVE signal circuitry (which drives the relay) so the behavior I'm seeing makes sense if C4 died and took a couple of things with it (or if something else died and took C4 with it). Here's where it gets kind of odd -- I spent some time testing diodes and transistors in the related area near C4 and while doing so I noticed that there are four diodes (D1-D4) listed on the schematic that are missing from my board. "Missing" as in someone clipped them out at some point -- there are just nubs of the leads left. I'm not sure why this would have been done, but there were a number of ECOs applied to this board (a few wires and resistors added) and I don't want to assume that if I just put four new diodes in that it won't cause other problems. Anyone know if there were other revision levels of the bias/interface board that would have done away with these diodes? Anyone have an H7140 they can easily crack open to compare? (It's actually relatively easy to get to, if you can get to the supply...) Thanks as always, Josh

10 years, 6 months

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