Lecture 2 Chapter 1 Flashcards
The PC is equal to what in the fetch stage?
The MAR
The IR is equal to what in the fetch stage?
The MBR
What purpose do interrupts have?
To improve processor utilization
What register does an Interrupt change?
The PC value
If an interrupt occurs what does the CPU do?
Finish current instruction cycle then processes the interrupt
After the interrupt process has completed what does the CPU do?
Return to the original process
What are the classes of interrupts?
Program
Timer
I/O
Hardware failure
What triggers a program interrupt?
overflows, dividing by zero, illegal machine instructions
What triggers a timer interrupt
A timer within the processor
What triggers an I/O interrupt
And I/O controller requesting service
What triggers a hardware failure interrupt?
A critical error in the computer such as a power failure
What are the two ways of handling multiple interrupts?
Disable interrupts
Define priority
When using disable interrupts for multiple interrupts what happens
The processor will ignore any new interrupts and leave them pending until free
If using priority based interrupt handling what happens?
Interiors are assigned a priority and higher priority interrupts will be handled first
What are the design constraints on computer memory
How much
How fast
How expensive
