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.
> 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
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.
> 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
> 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
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?
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
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.... ;)
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...