It seems that mame and mess merged, and you need to press scroll lock to toggle the mame controls when the keyboard is emulated.
For some reason, ESC does not quit MESS nor does TAB bring up the menu!
In systems with a full keyboard, the shortcut keys are disabled, because they are needed by the system being emulated. You need to press the Scroll Lock key (you get a message), then tab and other shortcuts will now work. Press Scroll Lock again to get the full keyboard back again.
wine does Windows API -> GNU/Linux syscalls + tons of wrappers for UI/Input/Output
WinE is not an Emulator :)
DOSBOX and PCem are x86 + ISA hardware Emulators or software VMs. They give you a full emulated PC but are quite a bit slower.
I think PCem was integrated into MAME at some point.
EDIT: it once was MESS. Now a part of MAME: http://mess.redump.net/
EDIT2: The CT486 driver in MAME really brings back some memories with that AMI BIOS: https://wiki.mamedev.org/index.php/Driver:CT486