Harwell Dekatron build + Open source firmware build tooling

[Organs Grinder]

Hi All,

Long time lurker/reader here, but I thought this build log and images would be worth sharing.

One of my favorite things was the day I saw the Harwell Dekatron computer(WITCH) at tnmoc.
So when I heard about a clock using Dekatron's that paid homage to WHICH, I had to have one!

I ordered the kit and Dekatron's from Grahame at:
http://www.sgitheach.org.uk/harwell.html

The case kit (with some changes) from Nick:
https://stocksclocks.com/index.php/harwell-a-dekatron-clock

It's taken me many months to get this all done as I have very little free time.

I am going to say up front that I am a little odd, and all this "bling" of LEDs and sounds puts me off.
Thankfully, the software that Grahame wrote is feature-rich and open source, with massive amounts of custom options for everything out of the box.

There are options to suit everyone's tastes and needs.

One thing I don't like the most is additional noise... Nick was very nice to help me create a custom front plate for the Harwell clock at an additional cost.

This front plate removed the holes/cutouts for the speakers. I have not installed the speakers into my kit at all.

Many thanks, Nick, I think it looks amazing. Along with the rest of the case.

Here is my front plate:

I also sleeved/braided all internal cabling and used only one colour of wire in the entire build.
Keen to know what everyone thinks!

I also sleeved the PSU:

One goal I did have is to be able to build all the source code from Grahame's Dropbox zip files.
I've now achieved that goal and all the firmware on my clock is running from builds I created from Grahame's source code.

You can find the build system here:
https://github.com/brendanhoran/sgitheach-harwell-earthly-build

The main branch (default) will build all firmware needed by the clock.
The tooling can be run on Windows, MacOS, and Linux. Making use of Docker and Earthly. This gives us portability and reproducibilityIt.
It will emit build artifacts that then can be used with Grahame's tooling/instructions as per the build manuals(s) or tooling of your choice to flash the devices.

I have a testing branch that also builds BOSSA to flash the Atmel SAM:
https://github.com/brendanhoran/sgitheach-harwell-earthly-build/tree/bossa-1-9-1-14-flash-sam

At the moment the testing branch only builds BOSSA for Linux.
I have used this testing branch to flash the Atmel SAM firmware with no issues, but again it is testing at this stage.

It needs some tweaking on the timing of some steps but it works.

Example output of the BOSSA flash step (firmware is built in another step before hand)

Please reach out to me directly or raise a PR if you have any questions or fixes for the build system.
Many thanks to Grahame for his countless detailed emails replying to my questions, would not have been possible without his help.


My next goal is to fix console output when connecting to the clock in a Linux environment (Minicom).

For now, you must disable colour output. (There is an option for that in the system.ini and a hardware jumper!)

I also plan to design a more minimal FACE for the clock later on, that I will send back to Grahame as well.

Many thanks,

Brendan

[Richard Scales]

Awesome work Brendan, really nice writeup and really interesting details on the software build process.
I particularly like the sleeving that you used - it really finishes things off very nicely can you share your source?
I don't suspect that it will be an easy process to retrofit to my Harwel, but it would be nice to have a go.

So, what's next?

 - Richard

[Nicholas Stock]

Really happy you like it Brendan! The single colo(u)r wiring, braiding and gold finish sockets add a certain panache... :) All new 'face' designs are welcome.

Cheers,

Nick

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[Organs Grinder]

Thanks, Richard, for the kind words.
Glad you found the write-up on the software build side interesting.
Can be a bit of a dull topic! (like my choice of bling...)


In this build, I used two types of sleeving.

For the IDC ribbon cable between the PSU and mainboard I used TechFlex:
https://www.techflex.com/general-purpose
* Mine might be some copy brand, but same/similar stuff.

For all the other sleeving, including the PSU. I have used paracord.
I remove the inner cord/line and just use the outside of the paracord.
Feed the wire through the paracord and heat shrink the ends.
I've got a range of sizes/colours.

I've sourced the paracord from either:
* outdoor shops.
* online shops (various) for more unique colours.

Some paracord seems better than others but it's hard to tell until you work with them.


The TechFlex, I picked up from a street vendor in Hong Kong. (Aplui street, SSP district for reference)
I think eBay might have some, but I'm unsure. It is not my favorite stuff to work with as it's quite stiff.
However, in a static case like this, it worked well.
I've not tried to source it recently.


Many thanks
Brendan

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