Chapter 7 BIOS ROM
Compaq Deskpro EP Series of Personal Computers
First Edition - April 1998
7-12
7.4.3 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
<2>=1 Screen blanked during transfer
(Failure)
CF = 1
AH = 86h or 87h
7.4.4 DRIVE FAULT PREDICTION
The Compaq BIOS provides direct Drive Fault Prediction support for IDE-type hard drives. This
feature is provided through two BIOS calls. Function INT 15, AX=E817h is used to retrieve a
512-byte block of drive attribute data while the INT 15, AX=E81Bh is used to retrieve the drive’s
warranty threshold data. If data is returned indicating possible failure then the following
message is displayed:
“1720-Intellisafe Hard Drive detects imminent failure”
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