To work with 8085 microprocessor, we should know Interrupt Sources and Vector Addresses in 8085 microprocessor. In 8085 microprocessor, it has two sources by using those sources we can interrupt the 8085 microprocessor. Those two interrupt sources are
- Software interrupt and
- Hardware interrupt.
In bellow we will see what is software and hardware interrupt.
Software Interrupts:
Software interrupt is special kind of interrupt which programmer can use as an instruction. If we look on instruction set of 8085 microprocessor then we found it includes eight software interrupt instructions called Restart (RST) instructions. Those are one byte instructions. And it make the processor execute a subroutine at predefined locations. That means when programmer use those instruction in between program, at the time of execution of the program it stop execution of current program and jump to the subroutine of that interrupt instruction. Instructions and their vector addresses shown in Table.
The software interrupts can treat as CALL instructions with default call locations. Now question is if we use more than one software instruction inside any program then which one perform first?
The concept of priority does not apply to software interrupts. They are inserted into the program as instructions by the programmer. And it executed by the processor when the respective program lines are read.
Hardware Interrupts and Priorities:
In 8085 microprocessor has five hardware interrupts. Those are INTR, RST 5.5, RST 6.5, RST 7.5 and TRAP. Now for unlike software interrupt hardware interrupt has own priority level. Their IVA and priorities shown in billow Table.
Hope that above all discussion Interrupt Sources and Vector Addresses in 8085 microprocessor clear your knowledge
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Interrupt of 8085 microprocessorinterrupt
