01H and 3fH (BX=0) keyboard input                   Keystroke Codes        
08H keyboard input (no output echo)                 ASCII Table            
07H raw keyboard input (no echo, no Break check)    Box & Line Characters  
06H console input and output (no-wait input)        ANSI Escape Sequences  
0bH get input status (and process pending Break)    I/O Redirection        
0cH clear keyboard buffer and wait for input                               
0aH and 3fH (BX=0) buffered keyboard input (input string)

02H and 40H (BX=1 or 2) display one character
09H and 40H (BX=1 or 2) display a string of characters

03H and 3fH (BX=3) AUX (serial port) input
04H and 40H (BX=3) AUX (serial port) output
05H and 40H (BX=4) PRN (printer) output
33H set Ctrl-Break check level      44H IOCTL (talk to device drivers)

INT 10H  BIOS Video Services        INT 33H  Mouse support
INT 16H  BIOS Keyboard Services     INT 2fH  MUX fns (print spooler, et al.)
                                                                              

Character I/O Functions