List and explain the interrupt available in microprocessor 8085.

 List and explain the interrupt available in microprocessor 8085.

• Interrupts are the signals generated by the external devices to request the microprocessor to perform a task. There are 5 interrupt signals, i.e. TRAP, RST 7.5, RST 6.5, RST 5.5, and INTR.

TRAP :

• It is a non-maskable interrupt, having the highest priority among all interrupts. Bydefault, it is enabled until it gets acknowledged. In case of failure, it executes as ISR and sends the data to backup memory. This interrupt transfers the control to the location 0024H.

RST 7.5 :

• It is a maskable interrupt, having the second highest priority among all interrupts. When this interrupt is executed, the processor saves the content of the PC register into the stack and branches to 003CH address.

RST 6.5 :

• It is a maskable interrupt, having the third highest priority among all interrupts. When this interrupt is executed, the processor saves the content of the PC register into the stack and branches to 0034H address.

RST 5.5 :

• It is a maskable interrupt. When this interrupt is executed, the processor saves the content of the PC register into the stack and branches to 002CH address.

INTR :

• It is a maskable interrupt, having the lowest priority among all interrupts. It can be disabled by resetting the microprocessor.
• When INTR signal goes high, the following events can occur −

1. The microprocessor checks the status of INTR signal during the execution of each instruction.
2. When the INTR signal is high, then the microprocessor completes its current instruction and sends active low interrupt acknowledge signal.
3. When instructions are received, then the microprocessor saves the address of the next instruction on stack and executes the received instruction.