I do actually have a ROM cartridge. The Alphatronic in this country (mine is actually branded Matmos as most are in this country as Matmos took over distribution) apparently came with a word-processing cartridge, which is what I have.
I don't know how to dump it directly as it is as it's in a little clear plastic case... not sure if I can open it. The 2764 (I think it is) inside it is soldered to the cart.
I may try and get an edge connector and a 28-pin socket, and wire it up that way if I can trace the tracks on the cart PCB.
There is only one cart slot, *but* there is also the disk port. When the disk drive is connected, the machine boots from the disk instead of ROM (I'm not sure what happens if no disk is present). This allows you to load Disk BASIC into the lower part of RAM instead of the ROM BASIC, and also allows you to boot straight into CP/M which uses the upper part of RAM, leaving the lower part free for CP/M programs.
You'll probably find that $A000 is for the cartridge, and $C000 is testing for the disk drive. There are no pin-outs in the manual for the disk connector but it's a custom 50-pin socket, so probably has access to the address and data lines of the machine too.
And before anyone asks, yes I do have the disk drive, and yes I do have working CP/M and Disk BASIC disks.
I'm on my way to my parents' right now though so won't be able to do any more investigating until the end of the year.
Oh, I've not dumped the disks yet but it's on my list of things to do. The disk drive uses a standard PD765 chip it seems (as I expected it would).