INT 15,21 - Power On Self Test (POST) Error Log (PS/2 except 30)

AH = 21h

AL = 00 read POST error log

= 01 write error code to POST error log

BH = Device code (if write)

BL = Device error (if write)

on return

CF = 0 if successful

= 1 if in error (AH contains code)

% if reading POST error log:

AH = 00h if successful

= 80h (PCjr and PC) = 86h for all other machines

BX = number of POST error codes stored

ES:DI pointer to POST error log

% if writing POST error log:

AH = 00h if successful = 01 POST error log full

= 80h (PCjr and PC) = 86h for all other machines