Hardware interrupts compared with software interrupts

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Quick Questions

Shade in the A or B circle for each question.

1. A user presses a key on the keyboard while a program is running. What type of interrupt is this?

A Software interrupt

B Hardware interrupt

2. A program tries to divide a number by zero. What type of interrupt is generated?

A Software interrupt

B Hardware interrupt

3. Which statement correctly describes the SOURCE of a hardware interrupt?

A The running program itself, such as a divide by zero error

B A device outside the running program, such as a mouse

4. Which statement correctly describes the SOURCE of a software interrupt?

A The running program or process itself

B A peripheral device such as a keyboard

5. The user moves the mouse while a video plays. Which type of interrupt is this?

A Hardware interrupt

B Software interrupt

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Key pressed on the keyboard while a program runs		Amouse moved -> interrupt signal sent to CPU
2result = 10 / 0		BA key press comes from the keyboard device outside the program, so it is a hardware interrupt, not a software interrupt
3A hardware interrupt is generated by a device and not by the program, for example when the mouse is moved		CA software interrupt, because the running program causes the error itself
4A software interrupt is generated by the program or process, for example when two programs try to use the same memory		DDivision by zero is caused by the running program, so it is a software interrupt, not a hardware interrupt
5Division by zero is a hardware interrupt because the CPU does the maths		EA hardware interrupt, because the signal comes from a device outside the running program
6A key press is a software interrupt because the user is running the program		Fmemory conflict -> interrupt raised by software

Definitions

hardware interrupt vs software interrupt

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Event: key press Type: ________ interrupt

Event: division by zero Type: ________ interrupt

Software source: the running _______

Event | Type key press | hardware memory conflict | ________

Hardware: from outside the program Software: from ______ the program

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A event ← "key press"

B source ← "running program"

C type ← "hardware interrupt"

D OUTPUT type

Question 2

A event ← "divide by zero"

B source ← "running program"

C type ← "hardware interrupt"

D OUTPUT type

Question 3

A event ← "memory conflict"

B source ← "mouse device"

C type ← "hardware interrupt"

Question 4

A IF source = "device" THEN

B type ← "software"

C ELSE

D type ← "software"

E ENDIF

Question 5

A INPUT event

B source ← GetSource(event)

C IF source = "program" THEN

D OUTPUT "hardware interrupt"

E ENDIF

Answer Key

Hardware interrupts compared with software interrupts

Section A: Quick Questions

B — Hardware interrupt

A — Software interrupt

B — A device outside the running program, such as a mouse

A — The running program or process itself

A — Hardware interrupt

Section B: Match the Pairs

Key pressed on the keyboard while a program runs → A hardware interrupt, because the signal comes from a device outside the running program

result = 10 / 0 → A software interrupt, because the running program causes the error itself

A hardware interrupt is generated by a device and not by the program, for example when the mouse is moved → mouse moved -> interrupt signal sent to CPU

A software interrupt is generated by the program or process, for example when two programs try to use the same memory → memory conflict -> interrupt raised by software

Division by zero is a hardware interrupt because the CPU does the maths → Division by zero is caused by the running program, so it is a software interrupt, not a hardware interrupt

A key press is a software interrupt because the user is running the program → A key press comes from the keyboard device outside the program, so it is a hardware interrupt, not a software interrupt

Section C: Definitions

hardware interrupt vs software interrupt — A hardware interrupt comes from a device outside the program (key press, mouse move); a software interrupt comes from the running program itself (divide by zero, memory conflict).

Section D: Fill in the Blanks

Event: key press
Type: hardware interrupt

Event: division by zero
Type: software interrupt

Software source: the running program

Event            | Type
key press        | hardware
memory conflict  | software

Hardware: from outside the program
Software: from inside the program

Section E: Spot the Error

B — A key press is signalled by the keyboard, a device outside the running program. The source should be "keyboard device", not "running program".

C — Divide by zero is caused by the running program itself, so it is a software interrupt. Line 3 should be type ← "software interrupt".

A — The source is a mouse device and the type is hardware, so the event must be a hardware event such as "mouse move". A memory conflict is a software interrupt.

B — If the signal comes from a device outside the program, it is a hardware interrupt. Line 2 should be type ← "hardware".

C — The output says hardware interrupt, which comes from a device. The condition should test source = "device", because a program source means a software interrupt.