CS401- Computer Architecture and Assembly Language Programming Assignment # 3 Fall 2010

Assignment

Question No.1 Marks: 10

Differentiate Synchronous and Asynchronous interrupts. Just give 2 to 3 differences also provide 1 to 2 examples.

Note: - Your answer must be to the point and in the bullets form otherwise your marks will be deducted.

Question No.2 Marks: 10

Read the following lines of code. It will read the mask register from port 0x21 and then set the 1^st bit in the register. As soon as it is written back to port 0x21; IRQ 0 which is derived by a timer device will be disabled.

in al, 0x21 ; read interrupt mask register

or al, 1 ; set bit to disable IRQ 0

out 0x21, al ; write back mask register

Take out line 2 i.e.

or al, 1

Modify it to solve the following parts

1. Set bit to disable IRQ5

2. Set bit to disable IRQ4

3. Set bit to disable IRQ7

4. Set bit to disable IRQ3

5. Enable IRQ5, IRQ4, IRQ3, IRQ7.