Q30370: Reading F11 and F12 Keys on Extended Keyboard

Article: Q30370
Product(s): See article
Version(s): 5.00 5.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 11-AUG-1989

The following program will allow you to read the F11 and F12 keys
on an extended keyboard. The key to this process is to call
_bios_keybrd() with the service argument 0x10. This will allow an
extended keyboard read. This program will sit in an infinite loop
until F11 or F12 is pressed. Note that the C run-time library
functions getch() or getche() will not be able to read in the extended
function keys even after the change above has been made.

#include <bios.h>
#include <stdio.h>
#define _EXTKEYREAD 0x10
#define MASK 0xFF00
#define ZMASK 0x00FF
main()
{
  unsigned value, nextval;
  while(1)
  {
  value = _bios_keybrd(_EXTKEYREAD);
  nextval = value;
  if ((value & ZMASK) == 0)         /* check low order byte for zero*/
                                    /* if zero, then we have extended key*/
    {

       if((nextval & MASK) == 0x8500)   /* buffer code = 8500h for F11 */
       printf("F11 key pushed\n");

       if((nextval & MASK) == 0x8600)   /* buffer code = 8600 for F12 */
       printf("F12 key pushed\n");
    }
  else
    printf("not an extended key\n");

  }
}