MESS supports the emulation of mac512ke with two floppy drives, “floppydisk1” (flop1) and “floppydisk2” (flop2), for disk images in .dsk, .img and .image.dc format.
This system requires full keyboard emulation to work correctly. At startup, full keyboard emulation mode is enabled by default. Whilst in full keyboard emulation mode, some key associated functionality may be disabled (like the ESC key for EXIT). The keyboard emulation mode is toggled using the “Scroll Lock” key (by default).
Introduced on 14th April 1986, the Macintosh 512ke was essentially a Macintosh 512k with the same 128k ROMs and double-sided 800 KB internal floppy drive as the Mac Plus.
It was sold as a poor man's Macintosh. Also, any existing Macintosh 512k could be upgraded to 512ke. (They could be upgraded to a Mac Plus, too, but this involved changing the motherboard.)
Since this model was discontinued a few months later (in August 1986), it may have just been a way for Apple to get rid of its excess Macintosh 512 motherboard. Or maybe they realized that 512 kb of RAM were not enough to run real-world Macintosh programs.