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“Computer Architecture and Design Interview Questions and Answers Guide represents the preparation of computer architecture and designs related jobs interview. Learn the basics and advances concepts of computer architecture and design with the help of these computer hardware architecture and design interview questions and answers.”



30 Computer Architecture Questions And Answers

23⟩ Explain What are the different hazards? How do you avoid them?

There are situations, called hazards, that prevent the next instruction in the instruction stream from executing during its designated clock cycle. Hazards reduce the performance from the ideal speedup gained by pipelining. There are three classes of Hazards:

1. Structural Hazards: It arise from resource conflicts when the hardware cannot support all possible combinations of instructions simultaniously in ovelapped execution.

2. Data Hazards: It arise when an instruction depends on the results of previous instruction in a way that is exposed by the ovelapping of instructions in the pipeline.

3. Control Hazards: It arise from the pipelining of branches and other instructions that change the PC.

How to Avoid Hazards:

1. Structural Hazard: This arise when some functional unit is not fully pipelined. Then the sequence of instructions using that unpipelined unit cannot proceed at the rate of one one per clock cycle. Another common way that it may appear is when some resources are not duplicated enough to allow all combination of instructionsin the pipeline to execute. So by fully pipelining the stages and duplicating resouces will avoid structural pipeline.

2. Data Hazards: A major effect of pipelining is to change the relative timing of instructions by overlapping their execution. This overlap introduce the data and control hazards. Data hazards occur when the pipeline changes the order of read/write accesses to operands so that the order differs from the order seen by sequentially executing instructions on an unpipelined processor. It can be mimimized by simple hardware technique called forwarding or by adding stalls.

3. Control Hazards: They are also know as Branch Hazards. The simplest scheme to handle branches hazard is to freeze or flush the pipeline, holding or deleting any instructions after the branch until the branch destination is known. In this case branch penalty is fixed and cannot be reduced by software. The other scheme is predicted-not-taken or predicted-untaken and delayed branch.

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24⟩ Explain What are the five stages in a DLX pipeline?

The instruction sets can be differentiated by

* Operand storage in the CPU

* Number of explicit operands per instruction

* Operand location

* Operations

* Type and size of operands

Submitted by Sowjanya Rao (Sowjanya_Rao@Dell.com)

IF: Instruction Fetch ( from memory) ID: Instruction decode and register read EX: Execution of the operation or address calculation MEM: Data memory access ( i.e accessing the operand) WB: Write Back ( the result)

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26⟩ Explain What is MESI?

MESI stands for a protocol which is followed in shared processor systems. M - Modified E - Exclusive S - Shared I - Invalid

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28⟩ What are the components in a Microprocessor?

its a general purpose register. its components are one processor along with external ROM, RAM, etc

MICROPROCESSOR IS A PROCESSOR(CPU) embedded in a single chip BY VLSI DESIGN. RATHER,IT IS A CLOCK-DRIVEN,PROGRAM CONTROLLED CHIP

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