Electron Clone v3.0 - Adding Econet
July 2025 - At a recent ABUG Scotland meeting I picked up on a comment that I should add Econet, the Acorn propriety network to the clone. Over the following few days I gave it some thought and did some research on Stardot. I new from posts a few years ago that an Econet interface had been designed for the Electron and wanted to see how it was achieved. I read through two threads on the Econet interface, one on the development and a second on the build. The second thread had the design included so I downloaded that to see if I could fit the design directly on the Clone PCB.
The Econet interface was designed as a cartridge that plugs into a Plus 1 slot and I think someone also designed a nice case for the PCB. I could just use the cartridge but this is not the challange. The circuit can be broken down into various building blocks - the Advanced Data link Controller, The I/O interface, the station ID buffer and the glue logic including ROM 13 ROM 0/1, 2/3 decoding and Flash ROM.
More Reading on Stardot:
Econet Cartridge development
Econet Build Instructions
Econet Bridge with Integrated Econet Module, Econet Clock & Termination
The clone already has ROM 13 on board and with building the circuit directly on to the Clone PCB I also don't need to include the Flash ROM and its decoding circuits. So before I go any further I will reach out to the designer of the cartridge to check it's ok to incorporate it into my clone and hopefully get some source documentation to enable me to make the changes needed.
Meanwhile I'll read some books from my collection, wonder how I'm going to get eight more IC's and a DIN connector on the circuit board and find out more about Ken Lowe's Econet Bridge.
Before I commit to ordering a new clone PCB I decided to test the new circuit and glue logic on a much smaller PCB and when I'm happy with everything I'll make the changes to the Clone PCB.
The first item to update is the GAL glue logic. The sample logic was built on a different system to the one I use which is WinCupl.
So I had to convert it to the syntax used by WinCupl and then removed the ROM decoding. This allowed me to use a smaller GAL, a 16V8 instead of the 22V10.
The simplest PCB to test the reduced circuit and GAL logic on is a small cartridge which I put together in EasyEDA and ordered from JLCPCB - the board cost of just £3.65 for five.
Next up was to blow the NFS ROM and install it in ROM 13. The response on the screen is as expected without an Econet interface plugged in. No Clock and the Econet station set at 255 (&FF)
Please come back to see how this project progresses..