Maybe somebody with more info can come along and answer this better but...
It seems only certain MSX1 machines have floppy drives enabled in MAME. I have no idea which ones work well but at a glance try cf3300 or svi738. Unfortunately I don't have any of the MSX floppy software lists so I can't confirm this works.
For the Atari 8-bit, sadly it looks like nobody has given us cassette emulation yet. The driver looks to have a skeleton in place—hence the software list with only three items. (We also need ATX support for floppies. There's a mountain of software that could be added with ATX and cassette emulation.)