Electron Ultra RAM Replacement Module
One of the issues I had when developing and building the Electron Ultra was finding RAM chips that not only tested working in a RAM tester but also worked in the Electron. Passing the RAM tester test only gave me confidence that they might work in the Electron and not many did.
When I was making the Ultra compatible with the TMM41256 RAM IC's, of which I had plenty stock, I thought about but never persued the idea of using a TMS4164 RAM. It's only now while I'm between projects that the idea has resurfaced and I thought I'd build a small PCB to try it out.
This small module will plug into the RAM sockets and contain just one TMS4464 RAM IC. Here is a 3D image of the module.
If this works then I missed a trick when designing the Ultra's PCB. Towards the end of the build I was running out of space on the PCB and I could have saved the space of three IC's and more than half the power drawn by the memory, 4x40mA compared to 1x60mA. It would make up for the additional power of the Raspberry Pi Co-Processor.
I ordered five TMS4464 10nS and five 4464 12nS RAM chips and I also bought a cheap and cheerful RAM Tester. I tested each RAM and unusually this time they all passed.
Here's the PCB built and ready to try.
This is it plugged into the Ultra's RAM sockets. It is very low profile, in fact you can hardly see it!
and it works..
I have upgraded four of my Ultra's and all are stable. I will add this to my list of upgrades for any future Ultra versions.
There is no reason why a module can't be made for a standard Electron or even a SIL version for the issue 6 Electron. This PCB won't fit the standard Electron as the Electron has different socket spacing between the left and second left IC's! but can be easily updated to fit.
Construction details.