One of the issues with the rainbow is the z80a has no rom at all; its entire 64k address space is ram (62k shared with the 8088, and 2k dedicated for itself); because the z80 boots at 0x0000, I *assume* the shared ram is from 0x0000 to 0xF7FF and the dedicated ram is from 0xF800 to 0xFFFF; the RX02 floppy drive must connect via I/O, and the 8088 cpu has to have some way of holding the z80 at address 0x0000 using /HALT or /WAIT or /BUSREQ before it uploads code for it to run into the 8088 side of the shared ram.

Do we have schematics of the Rainbow on bitsavers or something?
EDIT: not on bitsavers, but here: http://www.os2site.com/dec/rainbow/doc2/index.html

LN

Last edited by Lord Nightmare; 05/06/12 02:45 AM.
"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"