Here are some more files:
I dumped the ROMs of the three Rainbow 100's I have - all are model B's - so they could well be identical, but I haven't checked. There's a text file inside the archive with descriptions of the machines and their add-on cards. DEC Rainbow 100 ROM images
The video card that provides graphics (rather than text) output is present in two of my three machines, it's using the 7220 controller. I can't read the two PAL chips on it atm, maybe someone else can jump in here.
If you want some (very bad) video clips of the "maxed out" Rainbow in action, here they are: From switch on to MS-DOS from the Winchester DOS and WordPerfect for the Rainbow Windows 1.03 and Write
I have to start Windows by entering the application program I want to see - plain "win" gives a blank "MS-DOS" window ... it's waiting for something, either a disk to come online or a mouse.