- There are some very useful subroutines within BIOS and DOS that can be used through INT
(interrupt) instruction.
- The INT instruction works like a FAR call. When it is invoked, it saves CS:IP and the flags on the
stack and goes to the subroutine associated with that interrupt.
- The INT instruction has the following format:
INT xx ;the interrupt number xx can be 00 – FFH (256 possible interrupts)

BIOS INT 10H PROGRAMMING
- INT 10H subroutines are in the ROM BIOS of the 80×86-based IBM PC.
- Much of the manipulation of screen text or graphics is done through INT 10H. There are many
functions associated with 10H depending on the value put in register AH.
- Among these functions are clearing the screen, changing the cursor position, changing the screen
color and drawing lines on the screen.