Acorn Electron AP6 2V2 Plus 1 expansion 

I've heard of them but never seen one. I believe Dave Hitchins has done a modern remake of it and had some for sale at leat recently. It's always difficult to know how far to push upgrading an Electron when I also have a BBC and Master. One of the attractions of the Electron is it does so much in a compact package (which I've slightly ruined with a Plus 1!) but, at the same time, it's clear a major issue with it was the slowdown of RAM access, especially in the high resolution/colour screen modes.

@@lsbyte Yh i got my electron in 1983. I could not afford the bbc micro which was twice as much. The electron was definately less powerful than the bbc micro but it was made to compete with zx spectrum and commodore 64

I recommend the "Advanced Sideways RAM User Guide" by Bruce Smith - it gives a really good explanation of everything, gives loads of examples in BBC BASIC and covers all models. The Advanced User Guide is also good as a reference but doesn't give you many useful examples. Good luck and enjoy!

Oh, and as for removing the Support ROM, there was about a minute of footage before that, where I was gently easing out the chip, before I sprung loose at the end! Editing can solve most screw ups (although can't solve the continuity error you might have spotted!).

@@lsbyte Thanks! That sounds like a good recommendation. I did look briefly through the advanced guide and vaguely followed the examples but the advanced sideways ram guide is one I'd not heard of. I'll go look.

@@lsbyte ah yeh sorry, when I said throw out it was bad language. I meant to say "program with ease"

​@@WistrelChianti - Ah! I see, the code, not the physical removal. ;) It's not too difficult when you know how: I used the Bruce Smith book as a template and then added my own service entry, so it didn't take long. Some early code in that book also gets the computer to print out the service call numbers being passed to the sideways ROM on startup, which was useful to pick a service call to lock up the machine on. All sideways ROMs need a special header, which is one of the initial obstacles, otherwise the ROM won't be activated and show up in a *ROMS listing. In particular, there's a need to put in a byte of option flags and there must be a copyright message (starting "(C)") with a byte pointing at the offset to it.