test-drb

test-drb@ccmp.vtda.org

101090 discussions

by athornton＠gmail.com

From: Liam Proven <lproven at gmail.com> > To: "Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > Subject: Re: Motor generator > > I think because for lesser minds, such as mine, [APL is] line noise. > > A friend of mine, a Perl guru, studied A-Plus for a while. (Morgan > Stanley's in-house APL dialect.) He said to me that "when I came back > to Perl, I found it irritatingly verbose..." and then was immediately > deeply shocked at the thought. > > I seriously think this is why Lisp didn't go mainstream. For a certain > type of human mind, it's wonderful and clear and expressive, but for > most of us, it's just a step too far. > > Ditto Forth, ditto Postscript, etc. > > Plain old algebraic infix notation has thrived for half a millennium > because it's easily assimilated and comprehended, and many arguably > better notations just are not. > > The importance of being easy, as opposed to being clear, or > unambiguous, or expressive, etc., is widely underestimated. > > Yes, that. C is a great assembly language preprocessor for a PDP-11. The PDP-11 is a beautiful, intelligible architecture, where things happen one at a time in sequence. This is easy to think about. Unfortunately it's got very little to do with the way that modern high-performance silicon gets stuff done. (Aside: it's also weird that the one-thing-at-a-time sequencing is the thing that feels logical and intuitive to us since it is absolutely not how our brains work.) I would argue that Forth and Postscript are hard to understand for a different reason than APL: APL is inherently vectorized, and requires, more or less, that you treat matrices as single entities. Not many people's brains work that way. It's hard enough to learn to treat complex numbers as single entities. Forth and Postscript require you to keep a really deep stack in your brain to understand the code, and people aren't really very good at doing that for more than three or four items (much fewer than 7 +/- 2). Both of these are much more difficult for most people to work with and reason about than something imperative and infix-based. The fundamental problem is the impedance mismatch between the way most people think (which would at the very least take a radical reframing of curricula to change, and might not work anyway: look at the failure of the New Math, which was indeed very elegant, taught mathematics from first principles as set theory, and was not at all geared to the way young children _actually learn things_) and where we can continue to squeeze performance out of silicon. This is really not tractable. I think our best hope is to make the silicon really good at generating and figuring out graphs so it can dispatch lots of pieces of what feels like a sequential problem in parallel and come out with the same answer as you would have gotten doing it the naive one-step-at-a-time way. But we've already done that, and, yeah, it mostly works, but the abstraction is leaky and then you get Meltdown and Spectre. I don't have any answers other than "move to Montana, drop off the grid, and raise dental floss." Adam

5 years, 1 month

Motor generator

by cctalk＠emailtoilet.com

Many thanks for all the info. I just wanted to make sure my recesses were right. I asked about MG because, in an audio forum, I see folks paying crazy money for AC cords and power line conditioners. I thought a good MG would solve many of the 'problems' they are trying to fix.

5 years, 1 month

Motor generator

by cctalk＠emailtoilet.com

In the deep recesses of my mind I seem to remember something about S/360 machines using a motor generator. If I am right was this to create a stable power source at a certain frequency or voltage?

5 years, 1 month

Lecture: Forth: from the minicomputer to the microcontroller, 2021-05-08, 19:00

by stueberahoo＠yahoo.de

Hi all, you're invited to the Update computer club[0] public lecture series "Updateringar"[1]! Update is a Swedish computer club founded in 1983 whose members tinker with all kinds of computers, from Raspberry Pi to PDP-12. The club has a big collection of historic computers. In this lecture series we'll talk about everything related to computers: Historic and modern computers, operating systems, programming, hardware projects, creating art with computers, building a computer museum, and more. When: 2021-05-08, 19:00 CEST Where: https://bbb.cryptoparty.se/b/upd-0mo-m2u-aq8 Forth: from the minicomputer to the microcontroller Forth is an almost esoteric programming language in the eyes of most modern programmers, but still worth learning if only to expand your horizon. On modern microcontrollers the strengths that made Forth stand out in on 1970s minicomputers are relevant once again: fast enough execution, low worst case latency, full control over the system, powerful metaprogramming, and interactive development. This presentation will show how to overcome the initially near vertical learning curve and get the Mecrisp Stellaris Forth system running on a STM32 microcontroller without breaking the bank. Prior exposure to microcontrollers or assembler is helpful, but not required. Once the Forth system is running we will use it to explore either the hardware it's running on or its implementation and available implementation tradeoffs. Jan Bramkamp (CCCHB) The lecture is free and open to everyone. Upcoming: 2021-06-12, 19:00: How to start and run a computer museum. Thiemo Eddiks (Oldenburger Computer-Museum) Hope to see you there, Anke P.S.: I hope this is not too offtopic, but I assume there are people interested in Forth here. [0] http://www.update.uu.se/index_eng.html [1] https://www.update.uu.se/wiki/doku.php/projekt:updateringar

5 years, 1 month

cctech Digest, Vol 80, Issue 5

by athornton＠gmail.com

Message: 18 > Date: Thu, 6 May 2021 15:18:04 +0200 > From: Liam Proven <lproven at gmail.com> > To: Jay Jaeger <cube1 at charter.net>, "General Discussion: On-Topic and > Off-Topic Posts" <cctalk at classiccmp.org> > Subject: Re: That VAXStation4000vlc 3W3 video connector > Message-ID: > < > CAMTenCGKYnC++cT2gfpCvvntTjv-FrvivhuoXLcjWDesf2WC9w at mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > On Wed, 5 May 2021 at 17:59, Jay Jaeger via cctalk > <cctalk at classiccmp.org> wrote: > > > I, for one, did find this helpful - one could make one of these up to > > test before possibly forking over the funds to build one properly. > > If anyone were up to making a small batch of these, I'd be happy to > pay for a few, plus shipping etc. I have 3 ? 4000VLCs and only 1 > monitor for 'em, and I hope to get them running again sometime... > > > I'd buy at least one, seeing as how it was my original question, and whatever I end up stitching together will be really gross. If whoever is doing it would ALSO do the much simpler DEC 15-pin to VGA adapter, I'd probably buy some of those too. Adam

5 years, 1 month

That VAXStation4000vlc 3W3 video connector

by prd＠decarchive.org

> On 4 May 2021, at 19:00, cctalk-request at classiccmp.org wrote: > > Message: 17 > Date: Mon, 3 May 2021 16:22:45 -0700 > From: Adam Thornton <athornton at gmail.com> > To: "General Discussion: On-Topic Posts" <cctech at classiccmp.org> > Subject: That VAXStation4000vlc 3W3 video connector > Message-ID: > <CAP2nic2zsyqsLo1dFTTPh4WFV6utS1Tt_4RMsROjsmw78+8zKQ at mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > I assume it would be way too much to hope that HD BNC would fit it? Does > anyone have a pointer to the actual physical dimensions of the itty-bitty > BNC-ish connector in the video port of the VAXStation4000vlc? If I can get > red, green, and blue out (assuming since there are only 3 connectors it's > sync-on-green) I can put together a sync splitter and turn it into VGA. I > have at least one decent multisync VGA monitor still, although none with > the RGB BNC inputs. Firstly, apologies if my response doesn't show up nicely in this thread --- I only receive the daily digests so I'm not sure how best to reply to a specific post... But on the subject of sourcing / making video cables with 3W3 connectors on one end, I also balked at the cost of the coaxial insets and decided to make an only marginally dodgy (if I do say so myself) cable out of half of an old VGA cable, three of the 'sleeves' / female connectors contained, in abundance, in every female D-sub connector, and a few bits of heat-shrink (see https://media.decarchive.org/DEC/VAX/VAXstation%204000-VLC/IMG_3941.jpg for a photo of this cable from an albeit sub-optimal angle). The resulting connections were surprisingly stable, however, were I to make another one, I'd replace the grounding alligator clip with a lug that can be screwed onto one of retaining nuts next to the VLC's 3W3 connector, and use longer bits of heat-shrink to fully insulate the outside of the RGB connectors... And just FYI, even as shown, the video quality was more than adequate (considering the resolution of the VLC's LCG framebuffer), however, I suppose one could always attach a shielded DA15 shell to provide a bit of extra noise suppression (as well as mechanical protection). Hope this helps, Peter

5 years, 1 month

PDP-8/I Negative-bus termination

by michael.99.thompson＠gmail.com

> > Date: Wed, 5 May 2021 00:03:05 -0700 > From: Josh Dersch <derschjo at gmail.com> > Subject: PDP-8/I Negative-bus termination > > Hey all -- > > Until this point I've never had any peripherals for my negibus systems > (apart from teletypes), and it occurs to me that I have no idea if the bus > needs to be terminated (and if so, with what). There are 6 slots in the > RF08 backplane (D01-D06) for daisy-chaining to the next device, which is > where I assume they'd go; the RF08 manual does not make it clear what this > looks like or if it's actually required, and I've gone through the > available PDP-8/I docs and I'm still at a loss. > > Can anyone with negibus experience point me in the right direction? > > Thanks, > Josh > The DEC Field Service Technical Manual has some notes on bus termination. It says: Termination is required on I/O cables longer than 20 ft., and may be desirable on shorter cables. For negative bus, use 220 Ohm shunt resistors to ground on IOP 1, IOP 2, IOP 4, BTS 1, BTS 3 and Initialize. No special termination module exists for the negative bus. -- Michael Thompson

5 years, 1 month

Motor generator

by michael.99.thompson＠gmail.com

> > Date: Wed, 5 May 2021 13:20:59 +0100 > From: <dave.g4ugm at gmail.com> > Subject: RE: Motor generator > > We had a Motor/Generator for our Honeywell L66. Not sure it was because it > wanted US voltages or just for a clean supply > Dave > I also worked on a Honeywell L66 that had two motor-generators. We used one at a time, and swapped the operational one each month. They cleaned up the noise in the incoming 208VAC 3-phase power, and the really heavy flywheel provided a little ride through for short term power drop outs. -- Michael Thompson

5 years, 1 month

400 Hz

by erik＠baigar.de

..not to forget, that the 400Hz equipment was readily available from powering aircraft on the ground before the engines take over. So although not cheap, they where cheaper than a custom design at an arbitrary new frequency

5 years, 1 month

400 Hz

by erik＠baigar.de

> Incidentally, a way to get three phase power at a frequency of your > choice is to use a "variable frequency drive". Please be careful with this! Have quite some experience in building three phase inverters from such small boxes for my various avionics projects. (1) The normal ones rectify the mains voltage (in EU this gives around 320V DC) and from this make PWM outputs on three lines. Yes, you can enter voltage and frequency (sometimes even more than 400Hz) digitally, but the outputs are ALWAYS PWM switching between 0V and 320V in the EU. Consequence: If you rectify these outputs you will get back your 320V, completely independent of your settings! You need to use a device called Sinus-Filter, i.e. a low pass using caps and Ls to smooth out and get rid of the PWM - only than you get the correct three phase. (2) The small boxes are only for motors (inductive loads). Connecting someting else (does not matter whether three phase or not) which e.g. has got EMC filters at the input containing caps, the relatively high frequency (e.g. 16kHz, often selectable) will easily toast them leading to a short. (3) The PWM-boxes do not isolate from mains, so you will have pretty high voltages at the PWM outputs with high frequencies which can be a challenge for isolations - so even if you set the inveter to 110V only, but power it >from 240Vmains, the isolation of your device needs to handle the full 320V! My biggest inverter based on such a small PWM motor drive inverter is described in my blog (including schematics)... http://www.baigar.de/TornadoComputerUnit/TimeLine.html#inverter1500 (4) DO NOT use these three phase boxes connecting one output and one input pin to your device thinking that this is a single phase output. Creating a "neutral" line at the output of such an inverter can be done, but it requires additional components and than you can use it as single phase device: Here I used a special transfomer after the Sinus filter with input in triangle and output in star configurations. So I get neutral PLUS insulation to mains... Good luck!

5 years, 1 month

400 Hz

by erik＠baigar.de

5 years, 1 month

PDP-8/I Negative-bus termination

by derschjo＠gmail.com

Hey all -- I cabled up the RF08 to my 8/I this evening and it's showing some very faint signs of life -- a DIML instruction appears to do the right thing. That's about it. Until this point I've never had any peripherals for my negibus systems (apart from teletypes), and it occurs to me that I have no idea if the bus needs to be terminated (and if so, with what). There are 6 slots in the RF08 backplane (D01-D06) for daisy-chaining to the next device, which is where I assume they'd go; the RF08 manual does not make it clear what this looks like or if it's actually required, and I've gone through the available PDP-8/I docs and I'm still at a loss. Can anyone with negibus experience point me in the right direction? Thanks, Josh

5 years, 1 month

IBM 4700 question

by h.j.stegeman＠hccnet.nl

Hi, Does anyone known which processor IBM used in the IBM 4701 ? Branch Controller (8? floppy disc) ? Regards Henk

5 years, 1 month

General Instruments Capacitive Keyboard Encoder

by pbirkel＠gmail.com

I'm currently reverse-engineering an AMPEX keyboard that uses capacitive key switches. The basic design employs a GI encoder coupled to an 8039 MCU supplemented by a 2K EPROM and 74LS373 (used to latch the ROM address set >from Port A while Port A is then used to read data back from the ROM). The 8039 MCU drives a bit-banged serial interface. The PCB identifies itself as AMPEX on the coper foil, although the key switch mounting-plate actually has a "General Instruments Quality Accepted" sticker. The EPROM is labeled "3512663-03 Copyright 1983 AMPEX CORP". The GI encoder is a DIP-40 labeled as "321239007 M2406-054-02 GI 8233 CBU TAIWAN". I seek technical documentation for this IC. It evidently is not a relabeled simple variant of the documented AY-3-4592 as it does not multiplex the input side of the matrix (sense lines), there are fewer output data lines, and the power pins are non-standard (Vcc = pin 37; GND = pin 16). Reverse engineering identifies this M2406-054-02 as supporting an 8 column by 16 row (3 unused in my case) matrix plus 8 output data lines. I can identify analogs of several pins on the AY-3-4592. My interpretation of the pin uses is that the necessary key-scanning behavior is generated using the 8039 ALE line (pin 11) as the encoder clock input. Proper documentation for this IC would be nice to come by! Pointers and suggestions appreciated. Thank you, paul

5 years, 1 month

That VAXStation4000vlc 3W3 video connector

by athornton＠gmail.com

I assume it would be way too much to hope that HD BNC would fit it? Does anyone have a pointer to the actual physical dimensions of the itty-bitty BNC-ish connector in the video port of the VAXStation4000vlc? If I can get red, green, and blue out (assuming since there are only 3 connectors it's sync-on-green) I can put together a sync splitter and turn it into VGA. I have at least one decent multisync VGA monitor still, although none with the RGB BNC inputs. Adam

5 years, 1 month

IBM 1410 FPGA Implementation Update - new github repository

by michael.99.thompson＠gmail.com

> > Date: Sun, 2 May 2021 15:38:33 -0500 > From: Jay Jaeger <cube1 at charter.net> > Subject: IBM 1410 FPGA Implementation Update - new github repository > Message-ID: <68c06711-e563-f1bf-8abc-090793bed752 at charter.net> > > The last 12 months I have been pretty busy working on my 1410 in FPGA > project, and there is now more to share, though I have not done much > actual work since February - been too busy playing with other "toys". 8D > > JRJ > The RICM has a 1401 control panel. It would be pretty cool to mount your FPGA to the back of it and get it to blink the lights the right way. https://www.ricomputermuseum.org/Home/interesting_computer_items/ibm-contro… -- Michael Thompson

5 years, 1 month

920M - and also the Argus 200 / 700

by erik＠baigar.de

Hi Jos! > in the UK around 1960 the Argus 200 was developed to control the Bristol > Bloodhound anti-aircraft rocket. This computer was one of the very first > transistor-based control computers. Absolutely - in these days Ferranti and Elliott where competitors on the European market for defecne computing! Very funny, that they later merged and today the legacy of both is distributed in the BAe and Leonardo businesses ;-) There are quite interesting stories, on occasions when the two had to cooperate before merging and in the ELDO project mentioned in my video, the computer was from Elliotts whereas the inertial sensor was from Ferranti (https://youtu.be/v-gF5g0nnoE?t=363). > In Switzerland the Bloodhound was on duty?? until 1999 ! One of the sites, > once top secret,?? is now a museum, and well worth a visit. > Check out https://www.museums.ch/org/de/Bloodhound-Lenkwaffenstellung Definitively worth a visit! I am also into the Ferranti navigation systems >from the 1970ties (https://www.youtube.com/watch?v=-EQqfxiGgd8) and since years I am trying to find out, what architecture its 32 bit computer is. Here I booked an extensive special tour and the team on mount Gubel organized some experts to join the tour - although I learned that the INS computer is not related to the Argus series, the visit was AMAZING! Also great there to see the technology of the almost Mach3 missile from the 1950ties. Erik.

5 years, 1 month

RS64 on a PDP-8?

by jnc＠mercury.lcs.mit.edu

Is there a controller to attach an RS64 disk to a PDP-8? The only controller for the RS64I can find is the UNIBUS RC11. Thanks. Noel

5 years, 1 month

Cipher C995 manuals

by drb＠msu.edu

I have a recalcitrant Cipher C995 9track drive. Does anyone have manuals for this thing? It seems to be enough different from the M990 to matter. Thanks, De

5 years, 1 month

Sprague 2X.1-1000 filter capacitors and 854-B power control assembly

by ccth6600＠gmail.com

Unfortunately once again I am having trouble with Sprague 2X.1-1000 filter capacitors. The two filter caps on a Lab-8/e rack's 854-B power control assembly appear to occasionally leak to ground more than the 30 mA tolerated by my RCD. Mostly it trips the RCD when I power off the system, but sometimes it even trips the RCD with the system powered off. One of the two filter caps is permanently connected across mains power and earth coming from the cable (i.e. it is before the power switch). The exact same filter caps were also used inside the LAB-8/e computer?s power supply. Early on I replaced these with a small PCB with a bunch of male spade connectors and two Y class safety caps. The PCB was designed to replace two of the Sprague filter caps in the side-by-side configuration used inside the LAB-8/e?s power supply where it is also hidden from view. The PCB was designed by Malcolm Macleod in Melbourne/Australia who hit the same problem. I got the PCB manufactured in China from his design. The 854-B power control assembly has the two Sprague filter caps sitting on either end of the assembly ? far from each other. Also the can of the capacitors is exposed at the back and clearly visible so even a newly designed PCB with a single set of safety caps wouldn?t look great and also wouldn?t be stable because there are only two mounting holes. I cannot think of a neat solution to resolve this. I could try to find an electrician willing to wire me a non-RCD protected socket into my study, but I can?t quite warm to that idea. The RCD is an important safety feature. By law now all houses are required to have their AC wiring protected by 30 mA RCD circuit breakers so I likely would have to do this myself. The other option would be to make or buy two terminal blocks with male spade connectors and connect the female spade connectors to those rather than the Sprague connectors. I could then also wire in the 2 Y class safety caps or even forego the filtering. It would mean drilling new holes into the power control assembly. Chuck(G) in the vcfed DEC forum suggested pulling apart the old "bathtub" capacitors and replacing their guts with modern safety caps. The caps contain toxic and carcinogenic PCBs so I am less than enthusiastic about that idea. The capacitor's metal can is soldered together so trying to desolder it would heat the mineral oil containing the PCBs which would make them even more harmful. There is no point in trying to hunt for ?new? Sprague 2X.1-1000 because they would all be ancient and have the same leakage problem. Any thoughts, ideas or suggestions? Best regards Tom Hunter

5 years, 1 month

IBM 1410 FPGA Implementation Update - new github repository

by cube1＠charter.net

The last 12 months I have been pretty busy working on my 1410 in FPGA project, and there is now more to share, though I have not done much actual work since February - been too busy playing with other "toys". 8D First, I finished working through all of the IBM 1410 and IBM 1415 Automated Logic Diagrams - generating VHDL and testing the results with test benches. [Note that this includes the built-in 1401 compatibility mode, activated at the flip of a switch.] That took most of 2020. So, the CPU generation in VHDL is now more or less complete, and I added a hand coded memory module for memory, as core is kind of hard to find on an FPGA development board. ;) I am currently using a Digilent Nexys 4, but I think it might have even fit on a Nexys 2 - there is plenty of room to spare, and there isn't anything in the VHDL aside from, maybe, the memory implementation (though even that is pretty generic VHDL). With this the CPU runs, at the very least, Unconditional branch (Jump), Halt, NOP and Set Word Mark instructions seemingly correctly - I haven't tried any others. Somewhat surprisingly, aside from issues with the hand coded VHDL in triggers and the need to communicate pins tied to logic one or zero, the auto-generated VHDL works untouched. I have updated the github repository for the C# database application that generates the VHDL from time to time (and which includes the complete database) at http://github.com/cube1us/IBM1410SMS There is now a *new* repository, http://github.com/cube1us/IBM1410FPGA which holds the generated VHDL, some hand coded VHDL modules for certain SMS cards (typically for triggers, for example), the console and test benches I used along the way, and VHDL "Integration Tests" which are designed to be loaded onto the board - the current one being IntegrationTest3. There will be, eventually, a third repository which will contain the C# code that "hosts" the IBM 1410 console and peripherals, communicating with the FPGA over a high speed serial over USB connection. I figured out that this should allow me to emulate peripherals without having to resort to sending data over Ethernet, SPI, I2C or the like. I have just started that, so it really isn't at a point that there is much to share. Once I have a console working (which will require a re-do of the console VHDL implementation, which right now communicates in ASCII, but should probably be using BCD), I should be able to pre-load into memory some of the CPU diagnostics, by loading a diagnostic routine into either my 1410 simulator (http://github.com/cube1us/1410), or Richard Cornwell's emulator in SimH and then taking a snapshot of "core" to pre-load into the FPGA. At that point I expect I will be able to test the CPU pretty thoroughly. I hope and expect that will happen this year sometime. Unfortunately, I do not have the ALDs (Automated Logic Diagrams) for the IBM 1414 I/O Synchronizers, but I do have the Instruction Logic Diagrams which should allow me to code VHDL to emulate card, tape and maybe eventually even disk functions, so those might take a while. If anyone cares.... ;) JRJ

5 years, 1 month

Looking for the person I sold an eMachines eOne to at the VCF Swap Meet on April 24

by tony.aiuto＠gmail.com

*I found more related goodies you can have for the shipping. You can reply direct to me or on this thread.*

5 years, 1 month

DEC PDP-11/45 backplane +5 ECO

by fritzm＠fritzm.org

Hi Josh, Among the pictures linked from your message about the H742a parts, there is one picture of you backplane. I have been looking for some time for information about the following 11/45 ECO: > KB11-00001 CODE: D May-72 [ECO] > > Problem: Etch carrying +5V current from Mate-n-Lock pins to backpanel pins is not heavy enough to carry required current. Correction: Run 24AWG wire in parallel with etch on panels which already have Mat-n-Lock assembly installed. Increase thickness of conductor with solder bead if Mate-n-Lock assembly not installed. PDP-11/45 system serial number 101 and later. The wiring arrangements at the top of your backplane look to be a bit different from mine, and I believe you may have this ECO implemented. While you have your backplane out, could I ask that you take some closeups around the Mate-n-Locks along the top? I'd be very interested to see the board traces and the details of the red bus wiring there. Pictures of the toasted 11/45 suggest that the original machine had the older power wiring scheme (distribution panel mounted vertically on back of cabinet instead of horizontally at top of cabinet, etc.) although your KB11A serial number badge is >2000, which is curious...

5 years, 1 month

DEC RF08/RS08 module placement info

by michael.99.thompson＠gmail.com

I sent Josh pictures of the complete RF08/RS08 that John Wilson donated to the RICM. I will send detailed pictures of the RS08<->RF08 cables next week. -- Michael Thompson

5 years, 1 month

Bounces

by binarydinosaurs＠gmail.com

Hi folks, Did anyone else get an email about excessive bounces today? I?ve not changed anything hosting wise forever so this is a bit weird. Cheers, -- Adrian Graham Owner of Binary Dinosaurs, the UK's biggest private home computer collection? t: @binarydinosaurs f: facebook.com/binarydinosaurs w: www.binarydinosaurs.co.uk

5 years, 1 month

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test-drb