4MB to 1MB of RAM in software?

[Darklord]

That's the cutoff I recall as well, but again I thought it was about formatting, not reading and that TOS could always read a MS-DOS-formatted floppy. Perhaps someone who knows for sure can set the record straight.

Er sorry, guess I wasn't clear. I also believe that from the get-go TOS could *read* DOS formatted floppies but couldn't
DOS compatible format them until TOS v1.4 and up.

HTH's. :)

[stephen_usher]

Indeed, the ST didn't generate unique ids in the FAT header for a start, so PCs wouldn't recognise a disk change for a start, plus the FAT12 format was simplified a bit, which confused MSDOS.

[rubber_jonnie]

A quick look here: https://en.wikipedia.org/wiki/Atari_TOS and it states in the 2nd line that DOS disk compatibility came with 1.04/1.4.