So I got my father's Atari 800 out again recently, and tried to start figuring out just what upgrades he had done to it, and how they might be useful. He told me at one point, and this was something like 30 years ago, that he was trying to get the 800 so that it would work like an XL (I had the 800 XL). The OS board has had work done on it, and the #2 memory card has a switch. Using SysInfo, it shows a 1920K (!) Axlon RAM bank. Searching AtariAge last night, I couldn't find a way to get into that bank for testing it, but I was able to use a couple of ATR files off of my SIO2SD to get it to successfully create a RAM disk. But I still have no idea what the actual capacity is. Here are some photos.
All cards in the Atari 800 with the top off.
RAM from slot 2, with physical switch