Software Interrupts

Software Interrupts

The software interrupts are program instructions. These instructions are inserted at desired locations in a program.   The 8085 has eight software interrupts from RST 0 to 7. If the external device places an  Opcode for any one of the RST instruction (RST 0 to RST 7), then 8085 pushes the contents of  PC onto the stack. It then branches the program control to the vector address of the corresponding RST instruction. The vector address for these interrupts can be calculated as follows: 
Interrupt number x 8 = vector address





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