0:412h                   Reserved (POST Status on PC Convertible)
 
 Length: 1 byte
 
    This byte is reserved by all machines but the PC Convertible and the
    PCjr. The PC Convertible uses it to hold the status of the POST
    (Power-on Self Test) operation. The PCjr uses it to count the number
    of keyboard transmission errors encountered in the infrared link.