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─────Run-Time Library───────────────────────────────────────────────────────
 
/* KEYBRD.C illustrates:
 *      _bios_keybrd                                              (DOS-only)
 */
 
#include <bios.h>
#include <stdio.h>
#include <ctype.h>
 
/* Macro to peek at a specified memory address */
#define peek( addr )        (*(unsigned char __far *)addr)
 
void main()
{
    unsigned key, shift, scan, ascii = 0;
    int kread = _KEYBRD_READ;
    int kready = _KEYBRD_READY;
    int kshiftstatus = _KEYBRD_SHIFTSTATUS;
 
    /* If bit 4 of the byte at 0x0040:0x0096 is set, the new keyboard
     * is present.
     */
    if( peek( 0x00400096 ) & 0x10 )
    {
        kread = _NKEYBRD_READ;
        kready = _NKEYBRD_READY;
        kshiftstatus = _NKEYBRD_SHIFTSTATUS;
    }
    printf( "New keyboard %s\n",
            (kread == _NKEYBRD_READ) ? "present" : "not present" );
 
    /* Read and display keys until ESC is pressed. */
    while( ascii != 27 )
    {
        /* Drain any keys in the keyboard type-ahead buffer, then get
         * the current key. If you want the last key typed rather than
         * the key currently being typed, omit the initial loop.
         */
        while( _bios_keybrd( kready ) )
            _bios_keybrd( kread );
        key = _bios_keybrd( kread );
 
        /* Get shift state. */
        shift = _bios_keybrd( kshiftstatus );
 
        /* Split key into scan and ascii parts. */
        scan = key >> 8;
        ascii = key & 0x00ff;
 
        /* Categorize key. */
        if( (ascii == 0) || (ascii == 0xE0 ) )
            printf( "ASCII: no\tChar: NA\t" );
        else if( ascii < 32 )
            printf( "ASCII: yes\tChar: ^%c\t", ascii + '@' );
        else
            printf( "ASCII: yes\tChar: %c \t", ascii );
        printf( "Code: %.2X\tScan: %.2X\t Shift: %.4X\n",
                ascii, scan, shift );
    }
}
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