Re: [pidp8] Digest for pidp-8@googlegroups.com - 7 updates in 7 topics

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r cs

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Apr 27, 2026, 5:32:48 PM (7 days ago) Apr 27
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Can people who bought kits previously buy a tester kit?  I have both a PiDP-8 and 10 so far (and want the 11) but haven't had an opportunity to build either yet.

Thanks!
rcs

On Mon, Apr 27, 2026 at 4:56 PM <pid...@googlegroups.com> wrote:
Mike Markowski <mike....@gmail.com>: Apr 27 01:54PM -0400

Last summer (2025) I decided to refresh my ancient TECO know how. For
quicker searching I saved Google Lens OCR text to a file. While fixing
glaring OCR errors I thought why not format it a little...then a little
more...and then still more. It dawned on me that it was then practically
ready for LaTeXification! Before I knew it, it was sooo close to being a
usable document I finished it off. The pull of pointless addictions...
 
With some font work it could be made to look retro but not sure that's
necessary. It dawned on me today that some here might find it useful since
there is an OS/8 section:
 
https://udel.edu/~mm/projectDelta/teco.pdf
 
I'll be glad to learn of even the tiniest typos. I happened across two
today and will get an update on my page later. I also haven't explored in
depth how the 8/I's TECO differs from the 1980 manual.
 
'TECO madness; a moment of convenience, a lifetime of regret' - Dave Moon
 
Mike Markowski, who loves vi more than ever
Obsolescence <vermeul...@gmail.com>: Apr 27 07:23AM -0700

Wow! That is an major, major upgrade in terms of 'letting people experience
how these machines felt back then'.
 
Thank you!
 
Kind regards,
 
Oscar.
Obsolescence <vermeul...@gmail.com>: Apr 27 07:15AM -0700

I am unfashionaby late in this thread!
 
But I wonder if there is confusion caused by two generations of PiDP-8:
-- the old one up to circa 2018 had *only toggle *switches. DEP was also
just a toggle switch, not a momentary one. The user had to flip the DEP
switch UP and DOWN manually. If he forgot the DOWN part, no harm done, the
DEP signal only fired momtarily after a position change. But this means,
you got the desired inverted DEP by just inverting the signal when read
from the switches. No need to solder.
- PiDP-8s from 2018 *got momentary switches* where the original had them
too. So now, you not only have to invert the signal from reading the
switches, you have to turn the momentary DEP switch 180 degrees.
 
(toggle switches can be set UP or DOWN, momentary switches can be pushed
UP, but will move DOWN again when you let go of the switch)
 
Instead of dealing with the signal in software, for kits post 2018: because
you have to desolder the switch and put it in the other way already, just
make a tiny trace cut to the upper pin and use wire to connect the switch's
diode to the lower pin. It's the blue trace on the back of the PCB that you
have to cut (that is, in fact, why the trace is on the back of the board!):
[image: Screenshot From 2026-04-27 16-10-41.png]
 
Be wary of desoldering the switch though: it is easy to overheat the switch
in the process. In which case, sure, we can send a $1 replacement but
shipping costs are a pain these days. UnFun fact: last month, we spent $70
for sending out the average PiDP kit. Even a tiny switch incurs unpleasant
postage. Things are crazy these days. It took DHL 0.1ms to up its shipping
prices *yet again* after news about the Gulf broke out.
 
Kind regards,
 
Oscar.
Obsolescence <vermeul...@gmail.com>: Apr 27 06:54AM -0700

Bill,
 
On Friday, March 6, 2026 at 5:42:09 AM UTC+1 bill....@gmail.com wrote:
 
Warren, the original author of the image creation tool, recommended I
consider adopting rpi-image-gen as a replacement for his bosi image
creation tool.
 
 
The simpler way that I used for my disk images: just use a small SD card,
do a full install, then use dd to make an image. Or, much better: if you do
not have a small SD card anymore, partition it to shrink the root
partition. You can do that on a Linux laptop using gparted.
 
 
Oscar, if you're listening, I know you sell a lot of PiDP-8s these days
with people putting Pi4 and Pi5 processors in them. Do you have a sense of
the footprint of legacy ARMv6/ Pi Zero systems out there?
 
 
I do not really know. But like you, I *really* like the idea that you can
use an old Pi Zero that is too old for anything else and make a glorious
PDP-8 out of it. There's millions of unused old Raspberry Pi's in hobbyist
drawers, this is a good home for them. To loosely quote from an email I
once got from Eben Upton.
 
Using a Pi 5 really needs a line like 'set throttle 400k' or so in the simh
ini files. The Pi 5 is just silly fast.
 
To shoot of a loosely formed idea... these days, an esp32 would be a good
replacement option for the PiDP-8. I keep telling myself that I should make
a shim PCB with an esp32 or Pico W on it. Like Angelo did it for the
PiDP-1, you can just use a tiny web server and let a laptop deal with the
terminal and graphics display over wifi. Shrinking down simh to run on the
esp32 is feasible, spriteTM (aka Jeroen Domburg) did it for simh PDP-11.
One more thing on the infinite to-do list. Make the PiDP-8 Slow Again!
 
 
Kind regards,
 
Oscar.
Obsolescence <vermeul...@gmail.com>: Apr 27 06:43AM -0700

On Tuesday, March 10, 2026 at 5:23:16 AM UTC+1 sunnybo...@gmail.com wrote:
 
The PiDP-8 was not as easy. The faceplate keeps falling off, which I need
to fix
 
 
I have that! The bamboo case used to friction-fit the faceplate, but after
a couple of years the friction was no longer enough. I guess there's an
influence of moisture on the bamboo case - or something like that.
 
Multiple simple solutions:
 
- Put a sliver of black paper/thin cardboard in the inner ledge of the
case, then reseat the faceplate. It's probably enough
- Put some black plastic tape (electrical tape, it will not hurt the
paint on the back of the faceplate) on the back of the faceplate, fold it
just around the edges
 
There's other tricks, but these are sufficient from my experience. And keep
the faceplate removable.
 
If you have an older PiDP-8 where the bamboo case did not have a slot in
the back already, it is not that hard. Use a ruler with a box cutter knife
to cut grooves, then trace the grooves with the box cutter till you go
through the back. It is pretty much zero risk and surprisingly low effort.
Saying something about the material used in the back, I guess, but oh well.
 
Kind regards,
 
Oscar.
Obsolescence <vermeul...@gmail.com>: Apr 27 06:25AM -0700

The Kicad project files sloshed about on various places in the Google Group
and website. But now, everything is put here:
https://obsolescence.dev/pidp-parts-tester.html
 
See the bottom of the page for the download links.
 
Kind regards,
 
Oscar.
Obsolescence <vermeul...@gmail.com>: Apr 27 06:22AM -0700

All,
 
With apologies for not being online as much as I should:
 
the latest 'Newsletter' with a PiDP-8 section. I was just in time include
the big news on Bill Cattey's PiDP-8 software update:
https://obsolescence.dev/obsolescence-newsletter-may-2026.html
 
 
Kits now come with a little tester board (always remove the Pi before using
it!), which can be helpful when a LED or switch does not work after
building the kit. It's been there for a while, but I forgot to link to it
:-)
https://obsolescence.dev/pidp-parts-tester.html
 
Also, the above page contains links to the Kicad project files. Links to
them sloshed around the Obsolescence site and the Google Groups, now they
are all in one place.
 
As always, feedback is very welcome. I might be a bit slow to respond, but
that is not due to a lack of interest in feedback!
 
Kind regards,
 
Oscar.
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(There is no fireside like your own fireside.)


Obsolescence

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Apr 27, 2026, 8:19:39 PM (7 days ago) Apr 27
to PiDP-8
On Monday, April 27, 2026 at 11:32:48 PM UTC+2 rcs wrote:
Can people who bought kits previously buy a tester kit?  I have both a PiDP-8 and 10 so far (and want the 11) but haven't had an opportunity to build either yet.

I would have been happy to send it for free (the parts are basically nothing), but it is the shipping that kills the joy. International shipping is just awful these days. 

It's very easy, though, to make this yourself. A spare resistor, a cut-open USB cable for 5V and a LED are all you need. 

But if you have 
- a simple multimeter for continuity testing for testing a switch
- a 9V battery, wired through a resistor (200-1K ohm, does not matter much) can test a LED

I just made the parts tester to try out paneling at the PCB company, and discovered that the tiny PCB costs something like 40 cents or so. So, why not add it to the kits?

If you want, I have attached the Gerbers. It will be cheaper to upload it to JLCPCB (enable paneling) and you get 20 of them delivered for much much less than our shipping cost would be. Solder a cut-open USB cable to the 5V and GND pins, all it needs it a resistor and an LED.

To give you an idea how crazy shipping is... DHL just charged us $58 to deliver a tiny pack with  <100 grams of LEDs and diodes to Australia yesterday. They are nuts. And the others just as much. 


Kind regards,

Oscar.

tester.zip
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