Technical Reference Guide

8.5.1 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

Compaq D315 Personal Computer

07D0h

686Y4

CPQ0047

Compaq D325 Personal Computer

0830h

786A5

CPQ0059

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

8.5.2 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

Compaq D315 and hp d325 Personal Computers8-13

Featuring the AMD Athlon XP Processor

Second Edition – April 2003