I know alot of the rumors swirling about, was that schematics of the 2Meg upgrade (like the Disto) were intentionally mucked up.
I would suggest going to coco3.com, into the forums, and post a request there.
You could also check with Mark Marlette of cloud 9 (www.cloud9tech.com) who actually still produces hardware for the CoCo3!. I have their 6309+pro-tector, the TC^3 Scsi controller, and some of the software (SuperDrive, OS9 RomKit)
Excellent stuff, and he is really cool, to boot.
He's finishing up a "SuperBoard," which is IDE, 2MB upgrade, etc.... on one card for the CoCo3. You can find more info on their site.
Short of that, check the ftp.maltedmedia.com site for the TechRef/Service manual for the CoCo3, as well as the coco mailing list host at maltedmedia.com
Well I did find some schmatics though not sure if they are mucked up. I did get some cool stuff from cloud9tech and yeah Mark Marllete is a really cool guy. I now have SCSI and IDE controllers for my 2 coco3s. Don't really know what to do with the 3 coco2s I have as they are a pain. So then what about adding an external processor board to the multipak? I am mainframeOfPasta btw. Silly me now has two accounts. lol
Has anyone ever made an interface b/w the S-100 bus and the 40 line system of the coco3?