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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