INT E0 - REAL/32 - "C_STAT" - RETURN DEFAULT CONSOLE INPUT STATUS
CL = 0Bh
Return: AX = status
0000h no characters ready
0001h character available
may destroy SI,DI???
Note: after setting bit 0 of the console mode word with C_MODE, this function
will only return AX=0001h when the user presses Ctrl-C.