What is non maskable interrupt interrupt?

Answer 1

Non Maskable interrupts (such as those generated by power failure) cannot be blocked by the CPU.

Maskable interrupts are common device interrupts such as disk/network adapters interrupts which can be blocked by the CPU.

Answer 2

Non-maskable interrupt

A non-maskable interrupt (NMI) is a computer processor interrupt that cannot be ignored by standard interrupt masking techniques in the system. It is typically used to signal attention for non-recoverable hardware errors. (Some NMIs may be masked, but only by using proprietary methods specific to the particular NMI.)

]Overview

An NMI is often used when response time is critical, and when an interrupt should never be disabled in the normal operation of the system. Such uses include the reporting of non-recoverable hardware errors, methods for system debugging and profiling, and special case handling such as system resets.

In modern architectures, NMIs are typically used to handle non-recoverable errors, which need immediate attention. Therefore, such interrupts should not be masked in the normal operation of the system. These errors include non-recoverable internal system chipset errors, corruption in system memory such as parity and ECC errors, and data corruption detected on system and peripheral busses.

On some systems, an NMI can be triggered by the computer's user. Such applications include hardware and software debugging interfaces, and system reset buttons.

Debugging NMIs are typically used to diagnose and fix faulty code. In such cases an NMI is used to execute an interrupt handler that transfers control to a special monitor program. From this program a developer can inspect the machine's memory, and examine the internal state of the program at the instant of its interruption. Such NMIs also allow computers which appear to be hungto be debugged or diagnosed.

Answer 3

Maskable Interrupts can be masked i.e. they can be disabled by writing the proper control word in the control word register. Examples: RST 7.5, RST 6.5, RST 5.5 & INTR.

Non-Maskable Interrupts can't be masked i.e. they can not be disabled when enabled without servicing. They must need to be serviced. They even don't need EI & DI signals (EI= Interrupt Enable , DI= Disable Interrupt) to start or to halt. Example: TRAP.