Computer Architecture and Design Interview Preparation Guide
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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:

1 :: What are the basic components in a Microprocessor?

1)address lines to refer to the address of a block

2)data lines for data transfer

3)IC chips 4 processing data

2 :: What is MESI?

The MESI protocol is also known as Illinois protocol due to its development at the University of Illinois at Urbana-Champaign and MESI is a widely used cache coherency and memory coherence protocol.
MESI is the most common protocol which supports write-back cache. Its use in personal computers became widespread with the introduction of Intel's Pentium processor to "support the more efficient write-back cache in addition to the write-through cache previously used by the Intel 486 processor"

3 :: 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 instructional the pipeline to execute. So by fully pipe lining the stages and duplicating resources will avoid structural pipeline.

4 :: What is the pipelining?

A technique used in advanced microprocessors where the microprocessor begins executing a second instruction before the first has been completed. That is, several instructions are in the pipeline simultaneously, each at a different processing stage.

5 :: Cache Size is 64KB, Block size is 32B and the cache is Two-Way Set Associative. For a 32-bit physical address, give the division between Block Offset, Index and Tag.

64k/32 = 2000 blocks
2 way set assoc- 2000/2 = 1000 lines-> 10 bits for index
32B block-> 5 bits for block offset
32-10-5= 17 bits for tag

6 :: What is a Snooping cache?

DNS cache snooping is not a term the author just made up, it is known and discussed by some notable
DNS implementation developers, and a few interested DNS administrators have probably at least heard of it.

7 :: What is Cache Coherency?

Cache coherence refers to the integrity of data stored in local caches of a shared resource. Cache coherence is a special case of memory coherence. When clients in a system, particularly CPUs in a multiprocessing system cache occurs.

8 :: What is Virtual Memory?

Virtual Memory is a way of extending a computers memory by using a disk file to simulate add'l memory space. The OS keeps track of these add'l memory addresses on the hard disk called pages, and the operation in bringing in pages is called page fault.

9 :: 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

10 :: What is a cache?

It turns out that caching is an important computer-science process that appears on every computer in a variety of forms. There are memory caches, hardware and software disk caches, page caches and more. Virtual memory is even a form of caching.
Caching is a technology based on the memory subsystem of your computer. The main purpose of a cache is to accelerate your computer while keeping the price of the computer low. Caching allows you to do your computer tasks more rapidly. Cache technology is the use of a faster but smaller memory type to accelerate a slower but larger memory type. A cache has some maximum size that is much smaller than the larger storage area. It is possible to have multiple layers of cache.
A computer is a machine in which we measure time in very small increments. When the microprocessor accesses the main memory (RAM), it does it in about 60 nanoseconds (60 billionths of a second). That's pretty fast, but it is much slower than the typical microprocessor. Microprocessors can have cycle times as short as 2 nanoseconds, so to a microprocessor 60 nanoseconds seems like an eternity.