Computer Organization Interrupts and Status Register

Nonmaskable interrupts are denoted by the symbol NMI.

Internal interrupts are triggered by internal signals and RESET.

There are up to 10 external hardware interrupts in a processor.

The INT n instruction is used to trigger software interrupts.

A processor suspends what it is doing in the main part of the program and continues to execute the current task.

There are six groups of interrupts in a processor.

A processor cannot suspend what it is doing in the main part of the program.

The special routine that a processor passes control to is called the main program.

When a processor suspends what it is doing in the main part of the program, it passes control to the interrupt service routine.

The interrupt service routine is a part of the main program.

The NMI vectors are from type 1.

On NMI input, the NMI flip-flop is reset.

NMI type of interrupts can respond after a short delay.

Current flags, CS, and IP are pulled from the stack on NMI input.

NMI input must be active for one clock cycle.

The Status Register is an 8-bit register to hold indicator bits.

All bits in the Status Register are used.

The Status Register holds numeric values.

The Status Register is used to trigger interrupts.

The Status Register is a 16-bit register that holds both numeric and indicator bits.

The INT n instruction initiates a software interrupt.

Software interrupts have a lower priority than external interrupts.

A processor can continue executing the main program when an interrupt occurs.

The interrupt service routine is a separate program from the main program.

INT n is an external hardware interrupt.