$s = chr( 0xa8 ) . chr( 0x38 );;

$n = unpack 's', $s;;

( $day, $month, $year ) = ( 
     $n & 0x1f, 
   ( $n & 0x1e0 ) >> 5, 
   ( $n & 0xfe00 ) >> 9 
);;

printf "%4d-%02d-%02d\n", 1980+$year, $month, $day;;
2008-05-08