A computer can read or write a memory word in 10 nsec The co

A computer can read or write a memory word in 10 nsec. The computer has 34 CPU registers (including the program counter and status word), each one word long. When an interrupt occurs, all these registers are pushed onto the stack. What is the maximum number of interrupts this machine can handle in a second?

Solution

Answer:

An interrupt requires pushing 34 words onto the stack.

Returning from the interrupt requires fetching 34 words from the stack.

This overhead alone is 680 nsec.

Thus the maximum number of interrupts per second is no more than about 1.47 million, assuming no actual work is done for each interrupt.