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
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.
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?
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
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
> 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
>
> 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
>
> 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
..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
> 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!
..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
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
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
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
>
> 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
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.
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
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
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
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...
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
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