SECTION 2
Supporting DOS Applications
2-6 PEN*KEY
R
6200/6300 Hand-Held Computer Programmer’s Reference Guide
Broadcasting Messages
NPOWER uses the 2Fh software interrupt to broadcast certain power
management messages. NPOWER places 0530Bh in register AX and the event
code in BX before issuing the 2F interrupt. Any messages not shown in the
following paragraphs likely results in NPOWER reporting they are not valid.
Interrupt Vectors Supported by NPOWER.EXE
NPOWER.EXE interrupts are identified by the symbolic notation,
NPOWER
,
within each interrupt definition. The following paragraphs describe the
interrupt vectors that NPOWER hooks to achieve its resident functionality.
Broadcast Event
To modularize the broadcasting of APM events this procedure was added. The
special processing required by the retail CardSoft product is handled here.
Whenever the /SS:1 switch is specified:
"
No OEM events are broadcast
"
System suspend events are translated to user suspend events prior to
broadcasting them. This is done because CardSoft only acts on low
numbered events; and in the case of a Suspend event we would rather that
CardSoft did nothing. By converting it to a larger value, it does just that.
SystemResumeNotification
Use this procedure whenever there is any reason to perform resume processing.
It in turn checks before performing any processing to make sure that a
redundant call has not occurred. Assuming this is not a redundant call, the
following occurs:
"
INT 6Ch is issued to restore DOS clock from the RTC
"
Resume notification is broadcast (see also BroadcastEvent).
INT 08h ISR: Timer Tick
When NPOWER is disconnected from the APM BIOS, the timer tick ISR
installed by NPOWER does nothing but pass it on. When NPOWER is connected
to the APM BIOS, it continues to pass on the interrupt as the first thing it does.
Upon return from the previous handler it performs the following functions:
1. Turn off the backlight after a period of inactivity.
2. Manage the global backlight timer.
3. Turn on the backlight if the global backlight timer is enabled, and an event
has occurred that signals that the backlight should be turned back on.
4. Poll the APM BIOS event queue (details covered in the following
paragraphs).
Other than decrementing counters, the work performed by the timer ISR is done
after swapping to a local stack and incrementing the DOS busy flag. Recursion
is allowed, but only within the section of code that updates the counters. None of
the previous four functions are acted on when NPOWER is disconnected from the
APM BIOS. NPOWER connects to the APM BIOS when it loads (as a device
driver) and stays connected unless an INT 2Fh call is issued to perform a
disconnect.
2. DOS
Applications
