Type 41H Interrupt

Question

A particular real mode interrupt has a type number n=41H. If the corresponding ISR begins at address 09E3:0010, determine the location in the vector to store this address.

Solution 

The vector address is calculated by multiplying 41H by four.

This is done by rotating 41H left twice.

41H = 0100 0001; rotate left twice 01 0000 0100 = 104H

The offset address of the ISR is stored in the low-word location and the segment address in the high-word location.