讀取CMOS的記錄值取得XMS容量大小

 #include < dos.h >
 #include < stdio.h >
 #pragma inline      const int cmos_port_write = 0x70;
  const int cmos_port_read  = 0x71;      unsigned get_cmos( unsigned char low, unsigned char high );      int main()
  {
      unsigned ext;
      ext = get_cmos(  0x30, 0x31 );
      printf( "Installed extenden memory detected by POST:  %8uk\n", ext);
      return( 0 );
 }     unsigned get_cmos (  unsigned char low, unsigned char high )
 {
     unsigned word;
     unsigned char *p;
     unsigned char  l,h;         p = ( unsigned char *) &word;         disable();         outportb( cmos_port_write,high );
     asm jmp short $ 2
     h = inportb( cmos_port_read );         outportb( cmos_port_write, low );
     asm jmp short $ 2
     l = inportb( cmos_port_read );         *p = l;
     *(p 1) = h;         enable() ;
     return word;
 }