Tseng Qtec VGA 1024, Installation Manual

Page: 75 / 123

USING HARDWARE ZOOM, PAN FEATURE
The ZOOM programs once loaded are available at the software
interrupt level. Several function calls have been defined that
will allow you to take advantage of the hardware zoom functions in
the Qtec VGA1024. The function code is passed in the AX register
and any parameters requested are sent via the other 8088
registers.
The interrupt number is defined at the time ZOOM is intialized and
can be found by executing the following code sequence after the
ZOOM programs have been made resident:
Assembler
MOV A H , OFFH; NEW FUNCTION - QUERY ZOOM INTERRUPT
INT 16H ;
Output
AL+1 = Zoom interrupt number
AL
= Old BIOS keyboard handler interrupt number
BX = Hot key
Note that all windows and parameters are undefined until set by
the programmer.
Lattice C
#include<dos.h>
q__zoom__ int ( )
{
union REGS in, out;
in.x.ah=Oxff;
int8 6 (0x 16,&in,&out);
return(o u t .x .a l );
>
Once the application program has determined the interrupt number
of the zoom drivers it can invoke any of the zoom functions
described on the following pages.
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