Finally I got round to taking some decent photos of my conversion of a CARE Rom Cartridge to Acorn Electron sideways RAM. This is required because for some reason Acorn decided to move the R/W pin around on the cartridge interface.
So here is the front of the PCB + mods
You can see the original PIN A11 trace has been cut to allow PIN 4 to be wire linked with it. This wire link is on the back. The wire link you see here connects what used to be pin A4 input to decoding logic to +5V to pull it always high. This used to be the master CS pin which is not present on Electron.
And here is the back of the PCB + mods.
Here you can see the pin A4 to where A11 used to enter decoding logic wire link. You can also see the trace cut that used to be the original pin A4 trace.
With these mods the Electron recognises the cartridge as sideways RAM and the Slogger *rload commands work to load roms into these slots. There is however an issue with the images getting corrupted during load. I do not know what causes this. But it has been reported as happening on other sideways RAM projects using Plus 1 cartridge slots.