“When the CPU issues a command to the I/O module, it must wait until the I/O operation is complete”. It is programmed I/O , the word “wait” means ___________________.
A. the CPU stops and does nothing
B. the CPU does something else
C. the CPU periodically reads and checks the status of I/O module
D. the CPU wait the Interrupt Request Signal
To save PSW, PC and remainder onto stack, why the operations of restoring them is reversed? Because the operations of stack are __________.
A. first in first out
B. random
C. last in first out
D. sequenced
Using stack to save PC and remainder, the reason is ________.
A. some information needed for resuming the current program at the point of interrupt
B. when interrupt occurs, the instruction is not executed over, so the instruction at the point of interrupt must be executed once again
C. the stack must get some information for LIFO
D. the start address of ISR must transfer by stack
The signals of interrupt request and acknowledgement exchange between CPU and requesting I/O module. The reason of CPU's acknowledgement is ________________
A. to let the I/O module remove request signal
B. to let CPU get the vector from data bus
C. both A and B
D. other aims
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