Function 06h (6)         Direct Console Character I/O

Gets a character from the standard input device, if one is available;
or outputs a character to the standard output device. Does not echo
characters read or check for Ctrl-Break or Ctrl-C.

1. To input a character

On entry:      AH         06h
DL         FFh

Returns:       AL         Character
ZF         0    If a character is available
ZF         1    If no character is available

2. To output a character

On entry:      AH         06h
DL         Character

Returns:       Nothing

                                                                          

Notes:         If this function is used for input and no character
is ready, the Zero Flag is set; if a character is
ready, the Zero Flag is cleared and the character
value is returned in AL. Input is not echoed to the
standard output device.

A 0 returned in AL means that one of the "special"
characters (a function key or a cursor key, for
example) was input. A second call to Function 06h
will then return the extended code of the special
character. See the Key Codes table for a list of
special keys and their extended codes.

This function does not issue an INT 23h in response
to Ctrl-Break or Ctrl-C.

See also: 01h
See also: 02h
See also: 07h
See also: 08h
See also: 09h
See also: 0Ah
See also: 0Bh
See also: 0Ch
See also: Key codes

06h (6) Direct Console Character I/O