I've separated your ROM dump in its three 8K parts and preliminarily inserted them in my local MAME source ... the language part is identical to the Rainbow A ROMs we have in the driver, the emulation comes up with the other ROMs from your dump, but hangs after the printer/comm port error message ... probably the ROM patches have to be adjusted to the earlier code.
Most likely.... The quick disassembly I did show they were different, but I didn't delve...
I got brave and broke out my TJ866-CS MiniPro and tried to download the PROM since the markings are a little different than the documented markings. However, it doesn't understand the 6308 that I have. The ones listed have too many pins, etc. So I can't read it in.
Any recommended gear to read this in?
Thanks for the links. I've read through all the technical manuals (and even seem to have a couple that pre-dates the ones online I need to scan in), I was hoping to recover the A schematics themselves..