The Atari 800 had 4 user accessible slots for adding RAM and a ROM card. Normally, your machine came with at least two cards from what I understand.
The question is, if I removed all the cards from the machine, would it power up at all? Could you run a cartridge without the ROM card perhaps? As well, would it work without any RAM cards installed? What would the machine do if nothing was in there?
I'm asking this question since I need to diagnose an 800 which recently stopped working and displays only a dark gray screen. Since one of the diagnostic steps is to remove the cards to see if they're at fault, I'm curious if I can remove them all to determine some state.