Difference between Maskable and Non Maskable Interrupt

An interrupt is an event caused by a component other than the CPU. It indicates the CPU of an external event that requires immediate attention. Interrupts occur asynchronously. Maskable and non-maskable interrupts are two types of interrupts.

1. Maskable Interrupt :
An Interrupt that can be disabled or ignored by the instructions of CPU are called as Maskable Interrupt.The interrupts are either edge-triggered or level-triggered or level-triggered.

Eg: 
RST6.5,RST7.5,RST5.5 of 8085 

2. 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, system debugging and profiling and handling of species cases like system resets.

Eg:
Trap of 8085 



Difference between maskable and nonmaskable interrupt :

SR.NO. Maskable Interrupt Non Maskable Interrupt
1 Maskable interrupt is a hardware Interrupt that can be disabled or ignored by the instructions of CPU. A non-maskable interrupt is a hardware interrupt that cannot be disabled or ignored by the instructions of CPU.
2 When maskable interrupt occur, it can be handled after executing the current instruction. When non-maskable interrupts occur, the current instructions and status are stored in stack for the CPU to handle the interrupt.
3 Maskable interrupts help to handle lower priority tasks. Non-maskable interrupt help to handle higher priority tasks such as watchdog timer.
4 Maskable interrupts used to interface with peripheral device. Non maskable interrupt used for emergency purpose e.g power failure, smoke detector etc .
5 In maskable interrupts, response time is high. In non maskable interrupts, response time is low.
6 It may be vectored or non-vectored. All are vectored interrupts.
7 Operation can be masked or made pending. Operation Cannot be masked or made pending.
8 RST6.5, RST7.5, and RST5.5 of 8085 are some common examples of maskable Interrupts. Trap of 8085 microprocessor is an example for non-maskable interrupt.

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