Interrupt vector table in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an interrupt vector table in embedded systems?

It is a special table in memory that holds addresses of interrupt service routines (ISRs). When an interrupt happens, the processor uses this table to find and run the correct ISR.

beginner

How does the processor use the interrupt vector table?

When an interrupt occurs, the processor looks up the interrupt number in the vector table to get the address of the ISR, then jumps to that address to handle the interrupt.

intermediate

Why is the interrupt vector table usually placed at a fixed memory location?

Because the processor expects the table at a known address to quickly find ISRs without searching, making interrupt handling fast and reliable.

intermediate

In C, how do you typically define an interrupt vector table?

You create an array of function pointers where each pointer points to an ISR. This array is placed at the fixed memory address the processor expects.

advanced

What happens if an interrupt occurs but its vector table entry points to a null or wrong address?

The processor may jump to an invalid location causing a crash or undefined behavior, so every interrupt vector must point to a valid ISR or a default handler.

What does the interrupt vector table store?

A Data values for interrupts

B Memory addresses of variables

C Processor status flags

D Addresses of interrupt service routines

The interrupt vector table stores addresses of ISRs to handle interrupts.

Where is the interrupt vector table usually located?

A At a fixed memory address

B Random memory location

C Inside the CPU registers

D In external storage

It is placed at a fixed memory address so the processor can find it quickly.

What is the role of the interrupt vector table when an interrupt occurs?

A To disable all interrupts

B To find the ISR address and jump to it

C To reset the processor

D To store interrupt data

The processor uses the table to find the ISR address and execute it.

In embedded C, how is the interrupt vector table commonly implemented?

A As an array of function pointers

B As a linked list

C As a string array

D As a set of variables

An array of function pointers points to ISRs for each interrupt.

What can happen if an interrupt vector points to an invalid address?

A Processor resets automatically

B Interrupt is ignored safely

C Processor may crash or behave unpredictably

D Interrupt is handled by default

Jumping to an invalid address can cause a crash or undefined behavior.

Explain what an interrupt vector table is and why it is important in embedded systems.

Think about how the processor finds the right code to run when an interrupt happens.

Describe how you would implement an interrupt vector table in embedded C.

Consider how C handles functions and memory layout.