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  Interrupt

Interrupt is the method of creating a temporary halt during program execution and allows peripheral devices to access the microprocessor. The microprocessor responds to that interrupt with an ISR (Interrupt Service Routine), which is a short program to instruct the microprocessor on how to handle the interrupt


Types of Interrupts



Hardware interrupt

it is caused by any peripheral device by sending a signal through a specified pin to the microprocessor. The 8086 has two hardware interrupt pins, i.e. NMI and INTR. NMI is a non-maskable interrupt and INTR is a maskable interrupt having lower priority. 

Maskable Interrupt 

An Interrupt that can be disabled or ignored by the instructions of CPU are called as Maskable Interrupt

 Eg: ► INTR 

Non-Maskable Interrupt 

An interrupt that cannot be disabled or ignored by the instructions of  CPU are called as Non-Maskable Interrupt. A Non-maskable interrupt is often used when  response time is critical or when an interrupt should never be disable during normal system operation. Such uses include reporting non-recoverable hardware errors  

Eg: ► NMI



Software Interrupts 

These are instructions that are inserted within the program to generate interrupts. There are 256 software interrupts in 8086 microprocessor. The instructions are of the format INT type where type ranges from 00 to FF





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