BIOS / Int / Int 15 / 21


            INT 15 - SYSTEM - POWER-ON SELF-TEST ERROR LOG (PS50+)

Input			Output
AX	21h	Subfunction	Status	AX
BX	Device ID	Error Code	Number of Error Codes Stored	BX
CX				CX
DX			Error Log	ES:DI
ES:DI			Set on Error	CF

Subfunction:    00h = Read POST log
                01h = write POST log (BH / BL)

Status:         00h = OK
                01h = List Full
                80h = Invalid Command
                86h = Unsupported

Note:   The log is a  series  of words, the first byte of which
        identifies the error code and the second the device.