test-drb

test-drb@ccmp.vtda.org

101090 discussions

by dittman＠dittman.net

I have a VT525 that I couldn't turn off. I took it apart and there's an adapter that connects the metal rod off the button on the front to the power switch inside. The adapter has crumbled and it feels like it was wax but it may have just been some plastic that has severely deteriorated. Before I try to work up some kind of replacement, has anyone already designed a 3D-printed replacement? I don't have a 3D printer but do have a friend that could print one for me. Otherwise, I'll see if I can come up with something. -- Eric Dittman

5 years, 6 months

9 track tapes and block sizes

by shadoooo＠gmail.com

Hello, I have a question about 9 track tapes and block sizes. What I know is that tape is subdivided in files by means of marks, and each file is subdivided in blocks of equal size. Programs like tar use a specific block size to create files on tape. However files can have different block sizes like bootloader file, installation dumps and root file system copy on 2.11BSD. Now suppose you find and unknown tape you want to preserve: using dd you could easily 1:1 copy tape files to hard disk files using a SCSI drive and Linux. But: how you know which block size is on the tape? Thanks Andrea

5 years, 6 months

IBM PC-DOS 2.10 explorations

by will.senn＠gmail.com

All, I've been delving into ancient IBM PC-DOS... 1.0, 2.0 and have landed on 2.10 as the experience I'm going to hang out with for a while. It's stable in QEMU and 86Box and I am able to run MASM 1.0, 2.0 and Pascal 1.0 and 2.0. 86Box is more true to old-school boxes, but qemu runs on my Mac, so I like using Qemu. But, Pascal seems to prefer 86Box, it prints weird characters in qemu w/writeln(), which is annoying, but I'm doing more assembly and BASIC at this point, so Qemu's emulation is sufficient. What I've got working: IBM PC-DOS 2.10 - seems to be working fine in both (installed to fixed disk) IBM Macro Assembler 1.0 and 2.0 - seems to be working fine in both (installed to fixed disk) IBM Pascal 1.0 and 2.0 - hokey in both, tricky about the floppy being present, regardless of debug fix, and doesn't like QEMU. QEdit 2.1 - works great in both (installed to fixed disk) I found some good books on BASIC, Pascal, and Assembly: Albrecht, 1990. Teach Yourself GWBASIC. (covers later BASICA sufficiently) Pardee, 1984. The Waite Group Pascal Primer for the IBM PC. (Great book) Metcalf and Sugiyama, 1985. Compute!'s Beginner's Guide to Machine Language on the IBM PC & PCjr. (Excellent book) Lafore, 1984. The Waite Group Assembly Language Primer for the IBM PC & XT. (Wordy, but good) Pretty much everything I've programmed works fine. Graphics stuff is better in 86Box where I can control the monitor that's attached, but no complaints. Some questions I have related to the exploration: 1. I'm curious if there are other folks out there doing similar stuff? 2. Most of the Assembly examples use DOS interrupt 21 for output. Is this typical of assembly programs of the time, or did folks use other methods? 3. I was able to find a lot of 5150/5160 and other manuals, but I couldn't find an IBM Macro Assembler 2.0 manual (there are plenty of IBM Macro Assembler/2 manuals, but those are for OS/2, not DOS). Does anyone know where I can find one online? 4. In y'all's view, what are the significant differences between IBM PC-DOS 2.10 and it's brother MS-DOS 2.x? 5. I'm thinking of moving on to 3.3 at some point, in your view, what are the advantages? 6. I'm happy to post here, but if y'all know of a more appropriate venue, please suggest it? Thanks, Will -- GPG Fingerprint: 68F4 B3BD 1730 555A 4462 7D45 3EAA 5B6D A982 BAAF

5 years, 6 months

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by jnc＠mercury.lcs.mit.edu

> From: Chris Hanson > There's an MXV11-B (M7195) on its way to me. :) Wow, you've got a really good fairy god-mother! I've been trying to buy one on eBait for some time now (in part to have one to take a photo of for the CHWiki), and no luck - they always get bid up into the sky. And here someone has one for you! Life is unfair! Noel

5 years, 6 months

Thompson's Space Travel running

by lars＠nocrew.org

Hello, Ken Thompson's space exploration simulation Space Travel will now run on the SIMH PDP-7 simulator: http://sebras.se/space-travel-2.mp4

5 years, 6 months

Identifying mystery TI ICs (Motorola MDP-1000 investigation continues...)

by couryhouse＠aol.com

The making of this computer? perhaps explain why I never had someone wander in and talk about designing or building a MOTOROLA MINICOMPUTER ....Ed# On Monday, October 5, 2020 Bill Degnan via cctalk <billdegnan at gmail.com; cctalk at classiccmp.org> wrote: On Mon, Oct 5, 2020 at 1:10 PM Al Kossow via cctalk <cctalk at classiccmp.org> wrote: > On 10/4/20 11:13 PM, Josh Dersch via cctalk wrote: > > > Just made a minor breakthrough; a random usenet post suggested that the > > MDP-1000 was just a rebadged General Automation SPC-12, and so it is.? I > > suspect the internals of the unit I have (which is badged as an > "MDP-6650" > > on the rear) are a bit different than either the MDP-1000 or the SPC-12 > > (and I'm no closer to finding answers to my IC identification questions), > > but it at least gives me another avenue to explore... > > > > (Bitsavers has a few items: > > http://bitsavers.org/pdf/generalAutomation/spc12/) > > https://www.computerhistory.org/collections/search/?s=spc-12 Is this a case of not being able to find the correct TI or Motorola IC guide or is there something unique / OEM about this one?? I do have some late 60's early 70's IC guides of these manufacturers that I can check, original bound paper copies.? Please advise. Bill

5 years, 6 months

Identifying mystery TI ICs (Motorola MDP-1000 investigation continues...)

by derschjo＠gmail.com

More mysteries while poking at the MDP-1000. Spent some time this evening working out the rest of the signals on the power harness (I suspect inputs for an LTC circuit and a "power good" signal, as well as something connected to a relay on the backplane, probably related to power control). There are a lot of unidentifiable ICs on the main CPU logic board and on the backplane, mixed in with bog-standard 7400-series TTL. Curious if anyone has any ideas, as my searches and perusal of datasheets/databooks on Bitsavers have turned up nothing. These are all TI-manufactured ICs, 1969 manufacturing dates, with "SN48xx" and "SN63xx" part numbers (a few omit the "SN" prefix.) I'm wondering if these are just standard 7400 ICs with special codes; for example there are several SN4816's near the edge connector for the I/O bus, where a 7416 might (?) make sense, and from some basic probing and following traces I think the pinouts make sense. (Everything's conformal coated so it's a real bear to beep things out...) Any ideas? Thanks again, Josh

5 years, 6 months

ancient 5" SMD message

by aek＠bitsavers.org

5.25" SMD drives From: David C. Jenner <djenner_at_earthlink.net> Date: Tue Jun 24 19:28:00 2003 I have complete docs (User's Manual and Reference Manual, both very long) for both of the Seagate drives (the manuals cover both). And a stock of the 1.2GB drives, including power supply and cables. And QD33 Qbus adapters. I'll be glad to entertain offers for these offline, especially trades for PDP-11 equipment. Dave --- wonder if - he is still on the list - still has the manuals

5 years, 6 months

Sun SPARCstation LX boot from CDROM?

by chentsay＠yahoo.com

Dear Tom, Does your Sun workstation is functional and read QIC -150 cartridge? I have some old 3M 6150 cartridges that was created by Sun Sparc workstation in 2000. One those cartridges, I have some my personal files I like to get them. If you can you read those cartridges, I can pay some money for you? Chen Tsay

5 years, 6 months

Modcomp computers and documentation

by lyokoboy0＠gmail.com

Greetings everyone, it's Been a while since i posted here. I had picked up some modcomp minicomputers over the past couple years. A modcomp classic, with a nice front panel with binary swiches, similar to a pdp 11. There is a modcomp 32 as well, the machine boots from internal floppy drives. I was eager to pick up these machines, and save them from being thrown out. I picked up all of the documentation as well. Everything. A truckload of os information. I started to scan it all, but about 3/4 of the way through, my scanner broke. The 32 machine was not stored in climate controlled conditions before i picked it up, and is a bit more worn. It is designed to boot off floppys to load the microcode into the cpu... but the floppys... id be supprised if anything survived. Stored in bad conditions. The classic has internal microcode roms and will not have the same troublesome problem. I have been unable to devote the time and space to these machines as i had planned. I have been far too busy working at ibm, i am planning to shut down my side interests and focus on my dec pdp 11 stuff and ibm mainframe. I am looking to see if anyone would be interested in buying these. I spent a great deal getting them moved and keeping them in cool climate controlled storage, i am looking to see if i can get any offers and break even. Keep in mind, they are the size of a computer rack and heavy. I will post back with pictures soon.

5 years, 6 months

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by jnc＠mercury.lcs.mit.edu

> From: Chris Hanson > My little LSI-11 system doesn't have a usable Line-Time Clock because > it lacks the register, which it expects to be in either an MXV11-B > (M7195) or a BDV11 (M8012). My power supply theoretically supplies the > LTC .. so my preference would be an M7195 ... > Does anyone have one they'd be interested in parting with? The MXV11-B is rare and expensive - I think because it's a Q22 card. The BDV11 is, on the other hand, fairly common, not not too expensive. If you can't find a reasonably-priced one (i.e. <US$50) one on eBait, Paul Anderson used to have some. If he's out, I can probably be convinced to part with one. The BDV11 has on Q18 _terminator_ functionality; there's an ECO to make that Q22,though. FWIW, both the KDF11-B and KDJ11-A have built in LTC's, if a CPU upgrade is feasible for you. Noel

5 years, 6 months

Manuals, catalogs, brochures posted on Archive.org

by pdp11＠saccade.com

Last year I found a box of material, much of it related to S-100 computers and the Sol I owned in the 1970s. I've scanned it in and posted it to the Internet Archive: https://archive.org/details/@j_peterson Folks researching obscure old devices (Biotech Electronics CGS-808, anyone?) may find something useful. I still have a few documents waiting to scan, but this is 98% of it. Cheers, jp

5 years, 6 months

IBM 3279 analogue board / schematics?

by mattislind＠gmail.com

I am helping a friend with his IBM 3279 terminal. I got the PSU working after reverse engineering it. Concluded that the SMPS control chip was a standard TDA 2640 in IBM disguise. But of course the thing didn't work with the PSU fixed. A fuse which was in series with the vertical deflection coil on the analogue board went toast together with a 200 ohm resistor in the vertical deflection circuit. https://i.imgur.com/O4YEsdL.jpg At first I thought this had to do with some kind of fault in the vertical deflection coil itself. It measured only 1.2 ohms. But checking the IBM MAP manual revealed that both deflection yokes are supposed to be less than 2 ohms. So there has to be something else. I powered up the analogue board with the 5V and 8.5V that is normally supplied by the PSU (left the 103V unconnected since it used for the HV mostly) just to see what happened. The power consumption was reasonable, 0.3 amps on the 5V and 0.16A on the 8.5V. I then probed around among all those annoying IBM marked chips and square aluminium boxes. I found one chip that had 250 kHz on a pin. The chip appeared to be a divider since there were also 125 kHz, 62 Khz 31 kHz and 15 kHz. It seems to be originating from a square aluminium box. And then I found a signal which was around 20 Hz on another chip. As far as I understand the 15 kHz would fit well with the 64us sweep in the manual. But what is the purpose of the 20Hz signal? Vertical deflection? http://bitsavers.trailing-edge.com/pdf/ibm/3279/SY33-0069-3_3279_Color_Disp… According to the above manual the frame sync is 10 ms for model 2 and 13.8 ms for model 3 (this is a model 3). And moreover if 20Hz is the frequency used for generating the vertical it could explain why the fuse blew since the current in the deflection yoke should normally increase linearly with time. Three times longer deflection period would yield a three time higher current, thus very likely to exceed the 1.5A rating of the fuse. So I am looking for either another analogue board for an IBM 3279 or a schematic for the thing or maybe both would be great. IBM stuff is annoyingly hard to repair... Has anyone seen schematics for the IBM 3279? Does anyone have a spare analogue board? /Mattis

5 years, 6 months

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by jnc＠mercury.lcs.mit.edu

> From: Chris Zach > Might have an older MXV11 as well, could the 18 bit one do this Ooh, good catch; yes, the MXV11-A also has an LTC. I too have an 'extra' one. The OP should probably check to see if his P/S generates the bus clock signal; most of the options we've discussed for him would need it. Noel

5 years, 6 months

Anyone want to part with a DEC MXV11-B (M7195) and/or M8012 (BDV11)?

by cmhanson＠eschatologist.net

My little LSI-11 system doesn't have a usable Line-Time Clock because it lacks the register, which it expects to be in either an MXV11-B (M7195) or a BDV11 (M8012). My power supply theoretically supplies the LTC but I haven't confirmed that, so my preference would be an M7195 if possible. Does anyone have one they'd be interested in parting with? I'm fine with shipping internationally and with paying a reasonable price, and I promise to take good care of it and pass it on to another good home if I should ever part with it. (Friends don't let friends recycle rare electronics.) Alternately, is there a "modern" Q-bus board that provides things like LTC (both the clock and the register), SLU, memory, etc.? -- Chris

5 years, 6 months

Concurrent Controls Multiuser DOS

by new_castle_j＠yahoo.com

I'm researching Multiuser DOS out of my own interest. A version made by Concurrent Controls specifically. However, I have been unable to find documentation on it to satisfy my curiosity on how it works and how it is configured. They must have somehow broken the 640K barrier or virtualized each user session, I'd like to understand it better. What were it's limitations, I'm guessing that each user didn't get direct access to hardware. Anyone out there have a document or experience with it? Thanks, Jonathan

5 years, 6 months

Compaq Portable II PSU - value of C13?

by jules.richardson99＠gmail.com

Hi all, Does anyone happen to know the value of C13 in a Compaq Portable II power supply? It's a small-ish tantalum that lives next to the heatsink between U6 and U7 - although mine doesn't live any more, having just roasted itself in spectacular fashion. Quite possibly there's some other fault at play, but on the other hand it may have just been its time; tantalums in vintage stuff seem a little prone to failure. cheers Jules

5 years, 6 months

Pro 350 Print Set

by robert.jarratt＠ntlworld.com

Manx lists MP-01394-00 as the Field Maintenance Print Set for the DEC Professional 350. I can't find this online and I was wondering if anyone has a scan of it by any chance? Thanks Rob

5 years, 6 months

General Turtle TT2500

by lars＠nocrew.org

Hello, I'm making a software emulator for the General Turtle TT2500. Does anyone have any information about it? It's hard to come by. Here's what I have learned: It's a custom TTL design by Marvin Minsky et al, with 64K 16-bit memory and 4K 16-bit control store. It has two displays attached, one for vector graphics, and one for text. There is a UART for talking to a host (presumably running Logo), and a keyboard.

5 years, 6 months

HP 3000, APL\3000, the HP 2641A APL Display Station, and stuff.

by boris＠summitclinic.com

Thanks for putting this out. Not a system I'm familiar with but did play around briefly with APL in 1969 on an IBM 360. Very nice emulator and managed to get it up and running once found an emulated HP graphics terminal. Pleasantly surprised that emulator CPU useage was very small (unlike BasiliskII which runs one CPU core at 100% when I run my old Mac programs) and played adventure came that came with it. Last time I played an adventure game of that nature was in 1981 and remember thinking how neat it was back then. >As some people here are aware, I have spent probably too much time this summer >hacking on J. David Bryan's excellent Classic HP 3000 simulator and trying to >build up the ultimate classic 1980s HP 3000 system (virtually speaking). > >I started with the MPE V/R KIT that's widely available and expanded >that into a >5x120MB HP 7925 disc system and configured things like the system directory >size and all the system tables to make a fully functional multi-user server. > >I then set about collecting as much old MPE software as I could find, which >included Keven Miller's collection of the old Contributed Software >Library tapes >which were conveniently available in SIMH format. This is a huge trove of cool >stuff including most of the classic mini/mainframe games (Dungeon, Warp, >Advent, etc., etc.) and even a little game called DRAGONS that was written in >1980 by a guy named Bruce Nesmith when he was in college and he used it >to get a job at TSR and went on to write parts of many classic D&D products >and eventually landed at Bethesda where among other things he was the >lead designer for another little game called The Elder Scrolls V: >Skyrim. I was >able to track Bruce down and give him a copy of the system with his 40 year >old game running on it. The CSL tapes also include other amazing goodies >that people developed and gave away over the years, including a FORTH and >LISP, as well as most of the system and utility programs that people used to >run their 3000 shops. It's quite fun to explore. > >I was curious how far we could push the 3000 simulator, so I hacked all >the memory bank registers to be six bits instead of four bits, and we >now have a simulated HP 3000 Series III that supports 8MB of memory, 4x >more than any physical system ever did. I started trying to do the same thing >for giant disc drives, but MPE turned out to have too much knowledge of >what the supported disc models look like to make it practical. Bummer. > >Since I met my first HP 3000 in 1980 (40 years ago this month), people would >talk about what was probably the most rare and exotic HP software subsystem >ever produced, APL\3000. APL on the 3000 was a project started at HP Labs >in Palo Alto in the early 1970s. They were likely motivated by the success IBM >was having with mainframe APL timesharing services. This would be the first >full APL implementation on a "small" (non-mainframe) computer. It would be the >first APL with a compiler (and a byte-code virtual machine to execute the >compiled code), it would include an additional new language APLGOL (APL >with ALGOL like structured control statements), and it managed to support >APL workspaces of unlimited size through a clever set of system CPU >microcode extensions that provided a flat 32-bit addressing capability (on >a 16-bit machine where every other language was limited to a 64KB data >segment). > >Because APL required these extra special CPU instructions that you got as >a set of ROM chips when you bought the $15,000 APL\3000, and because >APL ultimately failed as a product (another story in itself) and thus HP never >implemented these instructions on their later HP 3000 models, I never saw >it run on a real HP 3000, but over the years we talked about wouldn't it be >cool to find a way to get APL running again. > >With assistance and moral support from Stan Sieler and Frank McConnell >and others, I was ultimately able to reverse-engineer the behavior of the >undocumented ten magic APL CPU instructions needed to get it to run and >implement them as part of the MPE unimplemented instruction trap and now >APL\3000 runs again for the first time in ~35 years. Somewhat ironically, this >implementation method could have been used back in 1980 as I didn't >actually end up changing the hardware simulation code at all, and it should >also run (if a bit slowly) on any physical classic architecture 3000. > >So that was cool and all, but what is APL without all the weird overstruck >characters and whatnot? APL\3000 supports the use of plain ASCII terminals >through blecherous trigraphs like "QD for the APL quad character, but this >is hardly satisfying. So the quest was on to find a solution. Back >in 1976 when >APL\3000 was released, there was a companion HP terminal in the 264x line, >the HP 2641A APL Display Station, which was basically an HP 2645A with >special firmware and APL character set ROMs that supported all the APL >special characters as well as overstrikes (the terminal would take >X<backspace>Y >and lookup to see if it had a character to represent Y overstriking X and if >so it would show that on the display, and if that got transmitted to >the host it >would convert it back into the original three character overstriking >sequence). > >I briefly looked into the idea of hacking QCTerm or Putty or something, but >then I found out from Curious Chris that an HP 2645A emulator already existed >in the MAME emulator system! Since the '41 is basically just a '45 >with modified >firmware, and Bitsavers had both the character set ROMs as well as the >firmware ROMs from a '41, this sounded like it might be easy! There was a snag >however in that the firmware ROM images that were allegedly from a '41 turned >out to actually be from an ordinary '45. But we did have the >character sets and >one of the ROMs from the second CTL PCA. I put out a call on the Vintage HP >list to see if anyone might possibly have a lead on an actual HP 2641A, and >Kyle Owen responded that not only did he have one he could also dump the >ROMs for us. So a few days and a few hacks to F. Ulivi's MAME hp2645 driver >later we now have a functioning MAME HP 2641A terminal emulation, so you >can experience APL\3000 in all its original glory. I bundled up a somewhat >stripped down MAME along with my turnkey 3000 setup so both emulated HP >terminals are just a couple clicks away. > >So that's how I spent my summer vacation (who am I kidding, it's >pretty much all >vacation these days). It has been a lot of fun revisiting all this old >3000 stuff as >well as the numerous people I talked to along the way including some of those >who were around at APL\3000's birth (before my time). It was rather a lot of >work so I'd like to feel it might be useful to someone in the future >who is digging >into this part of history. Because of all the usual reasons, I don't >plan on hosting >it permanently until and unless we maybe someday get the licensing worked out >(the 50th anniversary of the HP 3000 will be in a couple years so maybe people >will get interested again then) but I will offer it up here to my >fellow computer >history nuts if you want to help ensure that it doesn't vanish if I >get run over by a >bus or something :) > >This is a simulated HP 3000 Series III (circa 1980) running MPE V/R >(circa 1986) >with 8MB of memory, all the language subsystems (APL, BASIC, BASICOMP, RPG, >FORTRAN (66), SPL, PASCAL, COBOL (68), COBOL II (74)), 20 years of users group >contributed software, many classic historical computer games, etc. Software >archaeologists can get lost in here for years. Oh, and thanks to Dave >Elward, the >HP 2000 Timesharing BASIC contributed library is even included (kinda sorta >converted to MPE BASIC) for good measure. This is a streamlined >turnkey edition >that's ready to run out of the box with no assembly required (all >batteries are included). >Currently, I only provide executables for Windows (sorry) but am in >the process of >getting the 3000 simulator changes (for large memory support) and the new MAME >hp2641 driver back upstream. Instructions and further details can be >found in the >README.txt hint book for this adventure. 94MB Google Drive link: > >https://drive.google.com/file/d/1bmXvHkBLbUeLAid73EJ4H1yQ2uwXQuRu > >Gavin > >P.S. I'm giving a talk on the history of APL\3000 and its resurrection >to the ACM APLBUG >group in a couple weeks. If anyone is interested I can provide more >details when I have >them.

5 years, 6 months

PSA to SparcBook 2 Users

by ian.finder＠gmail.com

There is a 1000uf 10v cap on the main logic board just above the Bt display controller. It is leaking... a lot. (4/4 samples so far) Go replace it, flush the area and scrub the with 99.9% IPA.

5 years, 6 months

[TUHS] Fwd: Choice of Unix for 11/03 and 11/23+ Systems

by jnc＠mercury.lcs.mit.edu

> From: Liam Proven > for my continuing education: what's a "Mini-Unix binary"? Two possible meanings; a system image for a Mini-Unix system (buildable under V6 with the standard V6 tool-chain of C-compiler/assembler/linker), and user command binaries (buildable with the C-compiler/assembler, but needing a special Mini-Unix linker - written in C, and compilable/runnable under V6). I've done both in my recent Mini-Unix work. (For those are are not familiar with Mini-Unix and LSX, they are both V6 Unix variants lobotomized to run on PDP-11's without memory management: -11/05's, etc. I'm currently working on getting Mini-Unix to run on an -11/03; not a major change, but not a model supported 'out of the box'. LSX is more heavily cut down, so it will run on even smaller systems - I seem to recollect 20KB or so - but that's not that useful nowadays, with semi-conductor memory being fairly common.) Noel

5 years, 6 months

Zuse Z4 - Oldest Surviving Computer in the World - Lost in the archives

by osi.superboard＠gmail.com

A few days ago, it was published on BLOC at CACM that a lost user manual for the Z4 and notes on flutter calculations was found in the ETH Z?rich archives. See: https://cacm.acm.org/blogs/blog-cacm/247521-discovery-user-manual-of-the-ol… Zuse Z4, a relay computer of 1945,? however, due to lack of documentation, its functionality was largely unknown. Now a manual for the machine has appeared at ETH Zurich, that was buried in the archives. And this in the digital age ... Thomas

5 years, 6 months

[TUHS] Fwd: Choice of Unix for 11/03 and 11/23+ Systems

by jnc＠mercury.lcs.mit.edu

> From: Liam Proven > Would the x86-32 "reimplementation" of v6 UNIX be able to mount and/or > read-write such filesystems? No, it looks like it uses a different fie-system layout. Besides; there's not much point: the big adantage of using V6 is that one can use the V6 tool-chain to prepare Mini-Unix binaries; XV6 wouldn't allow that. If all one wants to do is get files in or out, there's already a program (compilable with gcc, that uses Standard I/O) to read files out of a V6 filesystem. If there was any good need, it could be extended to write (although that would be non-trivial). Noel

5 years, 6 months

Datasheet / Info for Motorola SC5330 IC?

by derschjo＠gmail.com

I'm in the middle of working out the pinout for the power supply connector on the MDP-1000. I'm aided somewhat by a set of test points on the backplane, unfortunately the "+" and "-" symbols (in the solder mask labels next to the test points) are nearly indiscernible, so I'm trying to verify that I'm not mixing up + and - 15V. On the core memory boards are eight Motorola SC5330 IC's (datecodes from early 1969), which have pins connected to both the + and - 15V lines -- if I can find a datasheet I could pretty easily confirm which is which. Trouble is I can't find anything on this chip. I've scanned through the databooks on Bitsavers, no luck. Anyone have any ideas? Here's a picture in case that helps at all: https://1drv.ms/u/s!Aqb36sqnCIfMpIVXm5draSrWHGMzJg - Josh

5 years, 6 months

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test-drb