Chapter 4

l. Upon an interrupt, what has to happen implicitly in hardware before control is transferred to the interrupt handler?

3. Put the following steps in the correct order: actual work of the handler

disable interrupt

enable interrupt

restore ko from stack

restore state

return from interrupt

save ko on stack

save state

4// How does the processor know which device has requested an interrupt

6. In the following interrupt handler code, select the items that do not belong.

disable interrupts;

save PC;

save $k0;

enable interrupts;

save processor registers;

execute device code;

restore processor registers;

disable interrupts;

restore $k0;

disable interrupts;

restore PC;

enable interrupts;

return from

7/// In the following actions in the INT macrostate, select the items that do not belong.

save PC;

save SP;

$k0 +--PC;

enable interrupts;

save processor registers;

ACK INT by asserting INTA;

Receive interrupt vector from device on the data bus; Retrieve PC address from the interrupt vector table; Retrieve SP value from the interrupt vector table; disable interrupts;

PC +--PC retrieved from the vector table;

SP +-- SP value retrieved from the vector table;

disable interrupts;