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Apex PDT Technical Reference Manual 6 Utility Programs
COAM30002 Rev. 2.00 8/13/02
6-12
Interrupts
During scanning, all hardware interrupts are disabled, including
SMI (System Management Interrupts) used for power management
and keyboard input. The driver permanently hooks the following
interrupts when installed.
08h - Tick (hardware) interrupt. The driver when installed hooks
the interrupt. The interrupt is also re-vectored while the driver is
actively scanning.
09h - Keyboard (hardware) interrupt. All keyboard input is
examined for the <SCAN> key. The key is not placed in the
keyboard buffer if “BTN” is true. If the <SCAN> key is disabled
from automatic driver recognition (“-BTN”), the key code is
buffered as an
extended scancode (3800h) just like any other key.
User software should not take over this interrupt, but instead use the
standard AT BIOS Int 15h, function 4Fh,
keyboard intercept if
direct keyboard input is required. Note that the <SCAN> key
generates a raw scan code of 62h, which is translated during Int 09
processing to 3800h.
13h - Disk services interrupt. The driver will not “wake-up” while
disk I/O is in progress. The driver performs no disk I/O of its own.
1Bh - Control-break interrupt. The driver prevents recognition of
the <FN> + <U> key sequence while actively scanning. This is
required for safe TSR operation.
23h - Control-C interrupt. The driver prevents recognition of the
<Ctrl> + <C> key sequence while actively scanning. This is
required for safe TSR operation.
24h - DOS critical error interrupt. The driver prevents recognition
of DOS critical errors while actively scanning (critical errors are
buffered). The driver makes no use of DOS servi ces including disk,
keyboard, and screen I/O, nor will it generate a critical error from
within the driver itself.
28h - DOS Scheduler. The driver suspends multi-tasking while
actively scanning.
2Fh - DOS multiplex interrupt. This interrupt is hooked in
compliance with the de-facto standard for TSR use. The interrupt
along with a unique ID value, is used to communicate with the
driver and forms the basis of the API itself. User software may also
hook this interrupt in compliance with the standard techniques.