The Intel 8085 microprocessor supports five types of interrupts to handle different events or conditions.
• Interrupts provide a mechanism for the microprocessor to temporarily suspend its current task and respond to a specific event.
Here are the types of interrupts in the Intel 8085:
RST (Restart) Interrupts (RST 7.5, RST 6.5, RST 5.5):
• RST 7.5, RST 6.5, and RST 5.5 are hardware interrupts that are vectored to specific memory locations. They are often used for handling external events or for initiating specific routines.
• The interrupt vector addresses for these interrupts are 7.5 times the corresponding number (e.g., RST 7.5 vector address is 7.5 * 8 = 60).
TRAP Interrupt:
• The TRAP interrupt is a non-maskable interrupt that is intended for handling priority-level tasks or critical events.
• It has the highest priority among the interrupts in the Intel 8085.
INTE (Interrupt Enable) and INT (Interrupt Request) Pins:
• The INTE pin is used to enable or disable interrupts. When INTE is high, interrupts are enabled; when it is low, interrupts are disabled.
• The INT pin is the interrupt request pin. When an interrupt is requested, the microprocessor checks the status of the INTE pin.
External Hardware Interrupt (INTR):
• The INTR pin is another interrupt request pin that is used to request a hardware interrupt.
• If INTE is high and the microprocessor recognizes a high signal on the INTR pin, it acknowledges the external interrupt.
SID (Serial Input Data) and SOD (Serial Output Data) Pins:
• These pins are used for serial communication and can be used to interrupt the microprocessor during serial data transfer.
To summarize the interrupt Process:
- When an interrupt is recognized, the microprocessor temporarily stops its current task and saves the address of the next instruction in the stack.
- The microprocessor then transfers control to the corresponding interrupt service routine (ISR) located at the specific vector address.
- After executing the ISR, the microprocessor retrieves the saved address from the stack and resumes normal program execution.
