chapter 3 answer computer architecture

3.3 List and briefly define two approaches to dealing with multiple interrupts.

Answer :The approach are given bellow :

·         Disable all interrupts while an interrupt is being processed. 

·         Define priorities for interrupts and to allow an interrupt of higher priority to cause a lower-priority interrupt handler to be interrupted.
3.5 What is the benefit of using a multiple-bus architecture compared to a single-bus architecture?

Answer :Compared to single-bus architecture, the using of multiple-bus architecture have a great advantage in speed and of course, will affect performance also. Instead of using single-bus architecture, it is more convenient to use multiple-bus architecture. Using multiple-bus architecture will make each device to connect to own bus, which means that each device will have its own bus. This way, it will be faster to transfer data of each devices, so the data transfer doesn't have to stuck like in the single-bus architecture where many devices are connected to a single-bus, that will eventually reach the capacity of the bus and thus will make the data "queue". Of course, it will cost more to have multiple bus, but the cost will not match the need of faster speed, compared to the one of that single-bus architecture.

Fetch, Decode, Execute, Store

Executing a single instruction consists of a particular cycle of events; fetching, decoding, executing and storing.

For example, to do the add instruction above the CPU must

1. Fetch : get the instruction from memory into the processor.
2. Decode : internally decode what it has to do (in this case add).
3. Execute : take the values from the registers, actually add them together
4. Store : store the result back into another register. You might also see the term retiring the instruction.
5. 
   
   

   CISC v RISC

   A common way to divide computer architectures is into Complex Instruction Set Computer (CISC) andReduced Instruction Set Computer (RISC).