SECTION 2
Supporting DOS Applications
PEN*KEY
R
6200/6300 Hand-Held Computer Programmer’s Reference Guide 2-9
INT 15h API
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.
"
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).
"
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.
"
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.
"
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.
"
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.
"
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
R
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.
2. DOS
Applications
