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Technical Reference Guide
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
8-15
8.4.6 FLASH ROM FUNCTIONS
The system BIOS may be upgraded by flashing the ROM using the INT 15, AX=E822h BIOS
interface, which includes the necessary subfunctions. An upgrade utility is provided on a
ROMPAQ diskette. The upgrade procedure is described at the end of this chapter. Corrupted
BIOS code will be indicated by the keyboard LEDs during the boot sequence as described
previously in section 8.2.1.
8.4.7 POWER BUTTON FUNCTIONS
The BIOS includes an interface for controlling the system unit’s power button. The power button
can be disabled and enabled.
The INT 15, AX=E822h, BL=08h function can be invoked to disable the power button,
preventing a user from inadvertently powering down the system. This tri-modal function is
typically used in the ROM flashing procedure to reduce the chance of an accidental power down
while the BIOS is being upgraded.
Entry:
AX = E822h
BL = 08h
Return:
(Successful)
CF = 0
AH = 00
(Failure)
CF = 1
AH = 86, not supported
NOTE:
With the Disable function invoked the system can
still
be powered down by
holding the power button in for four seconds or more.
The INT 15, AX=E822h, BL=09h function is used to restore the power button to the state it was
in prior to invoking the Disable (BL=08h) function.
Entry:
AX = E822h
BL = 09h
R
R
e
e
t
t
u
u
r
r
n
n
:
:
(
(
S
S
u
u
c
c
c
c
e
e
s
s
s
s
f
f
u
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l
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)
)
CF = 0
AH = 00
(Failure)
CF = 1
AH = 86, call not supported