Intermec 6200 Reference Guide

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NPOWER monitors several functions using this interrupt vector, but it does not

act on any of them unless NPOWER is actively connected to APM BIOS.

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APM BIOS: Set Power State for OEM Backlight

(AX=5307h, BX=0E200h)

When NPOWER is loaded and connected to the APM BIOS, it may manage

the backlight timeout.  Backlight management can be disabled using the

/BL:0 and /GBL:0 switches.  With backlight management this function

keeps track of three possible states for the backlight: on, suspended, and off

(CX=0, 2, or 3 respectively).  Standby (CX=1) is treated the same as off.

Resume from the suspended state causes the backlight to automatically

turn back on.  A backlight resume occurs either when the terminal itself

resumes or when a key is pressed (assuming the global backlight timer is

enabled and active).

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APM OEM BIOS: Set Idle Timeout

(AX=5380h, BX=3107h)

This function is intercepted because NPOWER has to set the APM idle

timeout every time it connects to the APM BIOS.  All that is done with this

interceptor is to keep track of the last value used to set the timeout.  After

recording the new value, the function is passed on to the APM BIOS.

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APM OEM BIOS: Set Backlight Timeout

(AX=5380h, BX=3110h)

When NPOWER is loaded and connected to the APM BIOS, it manages the

backlight timeout.  This function call is intercepted to keep track of what

timeout value to use to control the backlight.

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Key Post Ċ (AX=9102h)

This function call is issued whenever the keyboard BIOS puts a key in the

keyboard buffer.  This occurs either in response to a keyboard interrupt, or

an INT 16h call that specifically requests that a key be posted.  Scanner

drivers use the INT 16h call to place keys into the keyboard buffer that are

received from the scanner.
This interceptor uses this function as a sign of activity that causes the

backlight to come back on if the global backlight timer is enabled.

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Key Pend Ċ (AX=9002h)

This function call is repetitively issued whenever the keyboard BIOS is

about to check for a key in the keyboard queue.  Unfortunately it is issued

prior to checking at least once.  This interceptor first checks to see if there

is a key pending.  If not, it issues a CPU Idle call prior to returning that the

wait operation has completed.  Note that if there is no key available, the

keyboard BIOS continues to issue this call repeatedly, so there is no need

for NPOWER to perform any looping.  This interceptor can be disabled

using the /WA:0 command line parameter.

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Wait for any System Event Ċ (AX=4100h)

INT 15h function AH=41h is defined as Wait for External Event."  When

AL=00h, the event that is to be waited on is any external event."  This

function call is not frequently used in the PC compatibles environment, but

it has been used by NORAND

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 products in the past.  The interceptor of this

function call simply issues a CPU Idle.
This interceptor can be disabled using the /WA:0 command line parameter.

Note this one switch is disabling two separate, but similar, functions.