Specifications

CARROLL TOUCH Appendix C - TAPI Function Reference
Touch System Programmer’s Guide C-15
The Touch Coordinate Report (report header = FEH),
Add Exit Point Coordinate Report (report header =
FDH), Non-Contiguous Coordinate Report (report
header = FCH), and Scan Report (report header = FBH)
are all classified as coordinate reports, and are enabled
by setting bit 0 of the event mask. All other reports are
classified as non-coordinate reports, and are enabled by
setting bit 1 of the event mask. To enable the user event
handler for all reports, set both event mask bits.
BL = Enable Bits
Bit 0= If 1, enable calls to event handler.
If 0, disable calls to event handler.
Bit 7= If 1, set user event handler address from
CX: DX.
If 0, do not set user event handler address.
CX = Segment address of user event handler.
DX = Offset address of user event handler.
Returns
AX = 7 (function number).
Notes
Hardware interrupts are disabled during the user event handler. The
interrupt enable flag is cleared with a CLI instruction.
Use of reentrant function calls such as BIOS calls in the user event
handler is acceptable, as is the use of TAPI function calls in the user
event handler. However, use of non reentrant function calls such as
DOS function calls is not acceptable.
The UEH should execute as quickly as possible to let the TAPI driver
continue to process hardware interrupts from the touch system. If the
UEH takes too long to return, the TAPI driver may miss hardware
interrupts from the touch system.
The UEH is called once and only once for each report. If reports were
pending when the UEH was installed, multiple reports could be in the
buffer the first time the UEH is called. If this condition is undesirable,
BL: X X
7 6 5 4 3 2 1 0