INT 12 - KEYBUI v2.0+ - INSTALLATION CHECK
CX = 1806h
Return: AX = kilobytes of contiguous memory starting at absolute address 00000h
CX = 1960h if installed
Note:   KEYBUI is a resident keyboard driver by Johan Zwiekhorst which allows
accented characters and box drawing on standard QWERTY keyboards; it
also provides break-to-DOS and screen blanking capabilities


12 - KEYBUI v2.0+ - INSTALLATION CHECK