Compaq 850 manual System ID and ROM Type, Edid Retrieve, Temperature Status

Chapter 7 BIOS ROM

7.5.1 SYSTEM ID AND ROM TYPE

Applications can use the INT 15, AX=E800h BIOS function to identify the type of system. This function will return the system ID in the BX register. These systems have the following IDs and ROM family types:

System	System ID	ROM Family	PnP ID
Deskpro EXS or Workstation 300	06C8h	686P5	CPQ0010

The ROM family and version numbers can be verified with the Setup utility or the Compaq Insight Manager or Diagnostics applications.

7.5.2 EDID RETRIEVE

The BIOS function INT 15, AX=E813h is a tri-modal call that retrieves the VESA extended display identification data (EDID). Two subfunctions are provided: AX=E813h BH=00h retrieves the EDID information while AX=E813h BX=01h determines the level of DDC support.

Input:

AX	= E813h
BH	= 00 Get EDID .
BH	= 01 Get DDC support level

If BH = 00 then

DS:(E)SI = Pointer to a buffer (128 bytes) where ROM will return block

If 32-bit protected mode then

DS:(E)SI = Pointer to $DDC location

Output:
(Successful)
If BH	= 0:
	DS:SI=Buffer with EDID file.
CX	= Number of bytes written
CF	= 0
AH	=00h Completion of command
If BH	= 1:
BH	= System DDC support
	<0>=1 DDC1 support
	<1>=1 DDC2 support
BL	= Monitor DDC support
	<0>=1 DDC1 support
	<1>=1 DDC2 support
(Failure)	<2>=1 Screen blanked during transfer
CF	= 1
AH	= 86h or 87h

7.5.3 TEMPERATURE STATUS

The BIOS includes a function (INT15, AX=E816h) to retrieve the status of a system’s interior temperature. This function allows an application to check whether the temperature situation is at a Normal, Caution, or Critical condition.

7-14Compaq Deskpro EXS and Workstation 300 Personal Computers Featuring the Intel Pentium 4 Processor

First Edition - December 2000