An interrupt is a signal from a device attached to a computer or from a program within the computer that requires the operating system to stop and figure out what to do next¹. Interrupts are useful to avoid the CPU waiting time for I/O operations and to handle events that need immediate attention¹.

There are two types of interrupts: hardware interrupts and software interrupts¹.

Hardware interrupts are generated by external devices and I/O devices when they need the CPU's attention¹. For example, when a user presses a key on the keyboard, the keyboard generates a signal that is sent to the processor to perform an action. This is a hardware interrupt¹.

Hardware interrupts are classified into two types: maskable interrupts and non-maskable interrupts¹.

• Maskable Interrupts: These are the hardware interrupts that can be delayed or ignored by the processor when a higher priority interrupt has occurred or when the processor is busy with another task. The processor can use an interrupt mask register to enable or disable these interrupts².

• Non-Maskable Interrupts: These are the hardware interrupts that cannot be delayed or ignored by the processor and must be serviced immediately. These interrupts are usually reserved for critical events such as power failure, memory parity error, or division by zero².

Software interrupts are generated by internal devices and software programs when they need to access a system call or handle an exception¹. For example, when a program tries to divide a number by zero, the processor generates a signal that invokes an interrupt handler to deal with the error. This is a software interrupt¹.