Answer #include <dos.h>
#include <stdio.h>
void main()
{
union REGS i,o;
i.x.ax=1;
int86(0x33,&i,&o);
getch();
}
+ ExplanationNot ModeratedTo write such program you must have one interrupt table. Following table is only small part of interrupt table.
This table consists for column. They are:
(1) Input
(2) Output
(3) Service number
(4) Purpose
Now look at the first row of interrupt table. To show the mouse pointer assign ax equal to 1 i.e. service number while ax is define in the WORDREGSstruct WORDREGS {
unsigned int ax, bx, cx, dx;
unsigned int si, di, cflag, flags;
};
And WORDRGS is define in the union REGSunion REGS {
struct WORDREGS x;
struct BYTEREGS h;
};
So to access the structure member ax first declare a variable of REGS i.e.
REGS i, o;
Note: We generally use i for input and o for output
To access the ax write i.x.ax (We are using structure variable i because ax is input
(See in the interrupt table)
So to show mouse pointer assign the value of service number to it:
i.x.ax=1;
To provide this information to microprocessor
we use int86 function. It has three parameters
1. Interrupt number i.e. 0x33
2. union REGS *inputregiste i.e. &i
3. union REGS *outputregiste i.e. &o;
So write: int86 (0x33, &i, &o);
This table consists for column. They are:
(1) Input
(2) Output
(3) Service number
(4) Purpose
Now look at the first row of interrupt table. To show the mouse pointer assign ax equal to 1 i.e. service number while ax is define in the WORDREGS