There are a number of mini-distros, many of which will fit on a floppy. But they are cli only. If you need x-windows you might give ByzantineOS a look. It takes up 32MB disk space. If this is a problem, you'll need to look elsewhere. The size you're talking about is getting close to embedded systems size. If you can boot from a usb key, you might look around at some of the distributions designed specifically for that. They are larger than 20MB, but being on a usb key that shouldn't be an issue.
Just out of curiosity, why the 20MB limitation? I haven't seen a drive that small for about 15 years. Or is it a partition thing?
CloudCutter |