Nice find! I have one of these in my storage room. The DOS card allowed our secretary to log in to some accounting software used by Nationwide Insurance at the time, using a modem. I was the one who set it up, but I never did get used to seeing Windows 3.1 load on a Mac. 
The DOS card will accept up to 32mb of RAM in its single slot. And even though Apple never officially supported it, you can throw a couple 128mb SIMMs in the 6100 and get 264mb of RAM -- WAY beyond what Apple's specs will tell you. Add a decent video card and you'd be amazed how much more powerful the computer is!
The DOS card will accept up to 32mb of RAM in its single slot. And even though Apple never officially supported it, you can throw a couple 128mb SIMMs in the 6100 and get 264mb of RAM -- WAY beyond what Apple's specs will tell you. Add a decent video card and you'd be amazed how much more powerful the computer is!