INT 16h,  11h (17)       Extended Keyboard Status                        many

    Checks to see if a character is available in the buffer. This service
    is provided to support the extended keyboard (101/102-key keyboard).

       On entry:      AH         11h

       Returns:       Zero       0, if character is available
                                 1, if character is not available

                      AX         If character is available, then set to
                                 character as in Service 10h

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       Notes:         This service is supported only on the AT dated
                      11/15/85 and after, the XT dated 1/10/86 and after,
                      and the XT-286.

                      If a character is available, the Zero Flag is
                      cleared and AX contains the ASCII value in AL and
                      the scan code in AH. The character is not removed
                      from the buffer. Use Service 10h to remove the
                      character from the buffer. See Service 10h for a
                      complete description of the meaning of AX if a
                      character is available.

                      This service is excellent for clearing the keyboard
                      or allowing a program to be interruptable by a
                      specific key sequence.

                      See Service 01h for an equivalent service that works
                      with all keyboards, not supporting the new keys on
                      the enhanced (101/102-key) keyboard.