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CS2253 COMPUTER ARCHITECTURE AND ORGANIZATION

TWO MARKS

1. Explain very briefly about ESDI Hard Drive

ESDI stands for enhanced small device interface was developed by a consortium of several manufacturers. ESDI converts the data into serial bit streams and uses the RLL encodingscheme to pack more bits per sector. ESDI drives store a defect map containing the locations of

bad and defective sectors on the drive.

2. Explain in brief about IDE

Integrated device electronics contains an integrated controller with the drive as a singleunit. Interface is a simple 16-bit parallel data interface and requires the data to be written anddoes not need to be told where and how to write the data on the disk. .IDE Interface supports 2drives one drive has to be configured as the master and the second as the slave.

3. What is SCSI?

Small computer system interface can be used for all kinds of devices including RAIDstorage subsystems and optical disks for large- volume storage applications.

4. What are the two types of latencies associated with storage?

The latency associated with storage is divided into 2 categories1. Seek Latencies which can be classified into Overlapped seek, Mid transfer seek and Elevator seek 2. Rotational Latencies which can be reduced either by Zero latency read or Write and Interleavefactor.

5. What are the data management activities involved in a storage?

a. Command queuing : allows execution of multiple sequential commands with systemCPU intervention. It helps in minimizing head switching and disk rotational latency

b. Scatter gather : Scatter is a process whereby data is set for best fit in available block of memory or disk. Gather reassembles data into contiguous blocks on disk or in memory

6. What do you mean by Disk Spanning?

Disk spanning is a method of attaching drives to a single host uadapter. All drives appear

as a single contiguous logical unit. Data is written to the first drive first and when the drive is full,the controller switches to the second drive, then the second drive writes until its full.

7. List some objectives for using RAID Systems

RAID systems are used to meet the following objectivesHot backup of disk systemsLarge volume storage at lower costHigher performance at lower cost

Ease of data recovery

High MTBF

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8. What are the different levels RAID?

There are six discrete levels of RIAD functionality. They area. Level 0 Disk Striping

b. Level 1 Disk Mirroringc. Level 2 Bit Interleaving of Datad. Level 3 Bit Interleaving with dedicated parity drivese. Level 4 Sector interleaving of data with dedicated parity drivef. Level 5 Block interleaving of data.

9. What do you mean by Write Behind caching with write Coalescing?

Write behind is the delayed write process that is , the data is not written to the disk.Instead it is written to a write buffer resulting in quicker writes. Write coalescing coalesces

multiple write requests in a single disk revolution thereby improving performance.

10. Give the classification of the Optical Media

Optical media can be classified asCD-ROM Compact Disk Read Only MemoryWORM Write Once Read ManyRewriteable - ErasableMultifunction WORM and Erasable

11. What is a Mini Disk?

Minidisk for data (MD-Data) is the data version of the new rewriteable storage formatdeveloped by sony Corporation for both business and entertainment as a convenient medium for carrying music , video and data. MD can be used in three formats to support all potential uses asfollows

A premastered optical disk A recordable magneto-optical disk A hybrid that is partially mastered and partially recorable

12. List some applications for WORM.Some of the application or WORM devices areOn-Line catalogs such as automobile partys dealer Large Volume DistributionTransaction logging such as stock trading companyMultimedia Archival

13. What are multifunctional drivesA multifunctional drive is a single unit which is capable of reading and writing a variety

of disk media. This type of drive provides the permanence of a read-only device as well as fullflexibility of a rewriteable device along with the powerful intermediate write once capability

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14. What are types of technology used in s multifunctional drive?Three types of technologies utilized for multifunctional drives are

Magneto Optical Disk for both rewriteable and WORM capabilityMagneto- Optical disk for rewriteable and dye polymer disk for WORM capabilityPhase change technology for both rewriteable and WORM capability

15. What is Migration and Archiving?The process of moving an object from one level in the storage hierarchy to another level

in that hierarchy is called migration. Migration of Objects to off-line media and removal of theseobjects from on-line media is called archiving.

16. How do we use a jukebox? A juke box is used for storing large volumes of multimedia information in one cost

effective store. Jukebox based optical disk libraries can be networked so that multiple users canaccess the information. Optical disk libraries serve as near line storage for infrequently used ate.

17. List a few requirements imposed by advanced multimedia applicationsSupport for windows based GUI, such as Microsoft Windows

Capability to run applications in Multitasking environmentsSupport for Multi User Applications

Network bases client server distributed applications

18. What is the use of High water marks in a cache?

Cache design use a high-water mark and a low water mark to trigger cache management

operations. When the cache storage fills up to the high water mark, the cache manager startscreating more space in cache storage. Space is created by discarding objects that have not beenmodified and writing back those object that have been modified.

19. What are the various cache usage in a LAN based system? In a LAN based system there can be as many as three stages of caches as follows

1. Disk Cache or System memory cache2. Hard Disk cache for each object server 3. Shared network cache for all object servers

20. What are the multimedia applications which use caches?

Some Multimedia application areas where cache is extensively used areMultimedia EntertainmentEducationOffice SystemsAudio and video Mail

21. Define the term RELIABILITY and AVAILABLITY.

RELIABILITYMeans feature that help to avoid and detect such faults. A reliable system does not

silently continue and delivery result that include interacted and corrupted data, instead it corrects the

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corruption when possible or else stopsAVAILABLITY:

Means features that follow the system to stay operational even often faults do occur. Ahighly available system could disable do the main functioning portion and continue operating at thereduced capacity

22. Difference between asynchronous bus and synchronous bus.

1. Synchronous bus on other hand contains synchronous clock that is used to validate each andevery signal.It is also synchronizing clock that is used to validate each and every signal. when it is specified clock speed is set for all time.

2 .Synchronous buses are affected noise only when clock signal occurs.Asynchronous buses can mistake noise pulses at any time for valid handshake signal.

3. A master that receives the bus grant signal and it requesting the bus must not propagate it on

down the design chain.The system control which receives the bus grant signal in VME bus .The other name for Synchronousis VME bus.

4. Synchronous bus designers must control with meta stability when attempting different clock signal Frequencies.Asynchronous bus designer must deal with events that like synchronously.

5. Synchronous bus of meta stability arises in any flip flop. when time will be violated.It must contend with meta stability when events that drive bus transaction.

6. Synchronous flipflop can range from nanoseconds to microseconds its range is from 20-45nanoseconds.

When flip flop experiences effects can occur in downstream circuitry unless proper design techniquewhich are used.

23. List out the Technique used for speeding up of Multiplication process.

There are two technique for speeding up the multiplication operation.1)the first technique guarantee that the maximum number of summands that must be added is n/2 for n-bit operands2)The second technique reduces the time needed to add the summands.

24. Differentiate between RISC (Reduced Instruction Set Computer)

1) RISC is fully emphasized on hardware.1) CISC is fully emphasized on software.

2)RISC machines generally have a relatively Small and simple instruction set.2) CISC machines generally have a relatively large and complicated instruction set.

3)RISC requires only fewer transistors.3) CISC requires more transistors.

4)This simplified design can result in faster and less expensive processor development , greater

reliability and faster instruction execution times.

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4) This simplified design can result in slower and more expensive processor development, lessreliability and slow instruction execution time when compared to RISC.

5) RISC is a micro processor that requires only limited number of instructions.5) CISC is also a microprocessor that requires large number of instructions.

6)It has small codes and high cycles per second.6) It has large codes and low cycles per second.

7) RISC instruction set provides simple instructions intended for more direct implementation of high level language operations and program sequencing control structures.

7) CISC instruction set provides any powerful instructions intended for more directimplementation of high level language operations and program sequencing control structures.

8)RISC instructions are well suited to pipelined execution that leads to high execution rates.8)CISC instructions are not suited for the pipelined execution.

9) RISC advantage is that they can be used effectively by optimizing compiler.9) CISC cannot be effectively used by the optimizing compiler.

10) Because of small instruction handling and sequencing control , chip area needed for morespace is available for larger register sets.

10) Because of larger instruction handling and sequencing control ,chip area needed for morespace is not available for larger register sets.

25. Define absolute address?

An absolute address in computing is the precise indication of a memory location withoutthe use

of any intermediate reference. This is when the memory address indicated contains the dataneeded.Synonyms: explicit address, specific address.26. Write short notes on instruction pipelining?

It is a technique which a sequential process into sub operations.Which each sub operation can be performed in a dedicated proceeding segments that are executedconcurrently with all other segment

27. State different types of hazards that can occur in pipeline.The types of hazards that can occur in the pipelining were,1. Data hazards.2. Instruction hazards.3. Structural hazards.

28. What is Register Renaming?If a temporary register assumes the role of the permanent register whose data it is holding and is

given the same name is called as the Register Renaming.

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29. What is the function of commitment unit?When out-of-order execution is allowed, a special control unit called as commitment unit is

used to guarantee in-order commitment. It uses a queue called the reorder buffer to determinewhich instruction should be committed next. This is the function of commitment unit.

30. What are the classification of data hazards?Classification of data hazard:A pair of instructions can produce data hazard by referring reading or writing the same memorylocation. Assume that i is executed before J.So, the hazards can be classified as,1. RAW hazard2. WAW hazard3. WAR hazard

31. How data hazard can be prevented in pipelining?

Data hazards in the instruction pipelining can prevented by the following techniques. Operand Forwarding Software Approach

32. Define the term Clock Rate.

They are two possibilities for increasing the clock rate, R. First, improving the IC technologymakes logic circuits faster, which reduces the time needed to complete a basic step. This allows theclock period P to be reduce and the clock rate R to be increased. Second, reducing the amount of

processing done is one basic step also makes it possible to reduce the clock period P.

33. How Compiler is used in Pipelining?

A compiler translates a high level language program into a sequence of machine instructions. Toreduce N, we need to have suitable machine instruction set and a compiler that makes good use of it.An optimizing compiler takes advantages of various features of the target processor to reduce the

product N*S, which is the total number of clock cycles needed to execute a program. The number of cycles is dependent not only on the choice of instruction, but also on the order in which they appear inthe program. The compiler may rearrange program instruction to achieve better performance of course, such changes must not affect of the result of the computation

34. What is meant by Anti dependence?

A statement S2 is anti dependent on S1 if and only if S2 modifies a resource that S1 reads and S1 precedes S2 in execution. The following is an example of an anti dependence: S1 x: = y + cS2 y: = 10Here, S2 sets the value of y but S1 reads a prior value of y.

35. What is Output dependence?A statement S2 is output dependent on S1 (written) if and only if S1 and S2 modify the same

resource and S1 precedes S2 in execution. The following is an example of output dependence:

S1 x: = 10

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S2 x: = 20Here, S2 and S1 both set the variable x.Posted by Roy Antony Arnold at 2:01 AM 0 commentsLabels: Computer ArchitectureComputer Architecture - Set 4

36. Explain the various approaches used to deal with Conditional pipelining? * A condition branch instruction introduces the added hazard caused by the dependency of branch

condition on result of a preceding instruction.* Branching instruction represent about 20 percent of the dynamic interaction count of most

programs.* The dynamic count is the number of instruction execution, taking into account the that same

program instruction are executed many times because of loops.These branching junctions can le handled by following ways,

1. Delayed branch.

2. Branch prediction.3. Dynamic branch prediction

37. How addressing modes affect the instruction pipelining?

Degradation of performance is an instruction pipeline may be due to address dependency whereoperand address cannot be calculated without available information needed by addressing mode for e.g. An instructions with register indirect mode cannot proceed to fetch the operand if the previousinstructions is loading the address into the register. Hence operand access is delayed degrading the

performance of pipeline.

38. Give the advantage and disadvantages of complex Addressing modes?Advantages: 1. Simplifies the memory references.2. Produces variable length instructions format.3. Instruction manipulates operands in memory directly.

Disadvantages:1. Hardware logic is needed to implement addressing mode which2. Causes computation to slow down.2. Some specialized takes are done which is used infrequently.3 .conditional codes break the sequence of instruction stream causing

39. What is superscalar processor?

Super scalar processor exploits parallelism which hasMultiple E_ Unit each of which is pipelined and it constitutes independentInstruction pipeline. The processor has PCU designed to fetch and decodeSeveral instruction concurrently which is issued to pipelined E_Units thatExecutes several instruction is the same.

40. What do you mean by out-of order execution? Is it Desirable?

In a pipelined processor with several instructions is process concurrently it is Possible for

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instruction to finish out of sequence, one instruction finishes before Another which is issued earlier.as for as main computation is concerned no Hazards will happen but if an interrupts occurs it createsthe problem.

41. How the interrupt is handled during exception?

* cpu identifies source of interrupt* cpu obtains memory address of interrupt handles* pc and other cpu status information are saved* Pc is loaded with address of interrupt handler and handling program to handle it.

42. List out Various branching technique used in micro program control unit?a) Bit-Oring

b) Using Conditional Variablec) Wide Branch Addressing

43. What are Hazards?A hazard is also called as hurdle .The situation that prevents the next instruction in the instruction

stream from executing during its designatedClock cycle. Stall is introduced by hazard. (Ideal stage)

44. Compare hardwired control unit and microprogrammed control unit Attitude HardwiredControl Micro Programmed control.

SpeedFastSlowControl function

Implemented in hardwareImplemented is softwareFlexibility

45. List out rules for Booth recoded multiplier?1. Start from LSB check each bit one by one.2. Change the first one as -1.3. Skip all succeeding ones (record them as zeros) until you see a zero,Change this zero as one.4. Continue to look for next one without disturbing zeros, proceed usingRules 2&3.Ex: - 01110? (14)Recoded form: 100-10

46. List put the rules for mul /div of floating point number? Multiply rule:1. Add the exponent and subtract 127,2. Multiply the mantissa and determine the sign of the result.3. Normalize the resulting value, if necessary.Divide rule:1. Subtract the exponents and add 127,2. Divide the mantissa and determine the sign of the result,

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3. Normalize the resulting value, if necessary.

47. Write short notes on?a) Guard bits.

b) Truncation.

48. Define the following terms.Overflow:In the single precision, if the number requires a exponent greater then +127 or in a double precision,if the number requires an exponent form the overflow occurs.Underflow:In a single precision ,if the number requires an exponent less than -26 or in a double presition,if thenumber requires an exponent less than -1022 to represent its normalized form the underflow occurs.

49. What are Number Notations?Most of the programming languages allow to specify the variable values or numbers in various

types of number system such as binary, decimal, hexadecimal etc. To tell the assembler that thenumber is specified using particular number system, assembly language provides number notation for each number system that it supports

50. What is the principle of booth multiplication?

Booth multiplication is nothing but addition of properly shifted multiplicand patterns.It is carried out by following steps:

a) Start from LSB. Check each bit one by one.

b) Change the first one as -1.c) Skip all exceeding ones (record them as zeros) till you see a zero. Change this zero as one.d) Continue to look for next one without disturbing zeros, precede using rules b), and c)

51. What do you mean by Register transfer?

Instruction execution involves a sequence of steps in which data are transferred from one register to another. For each register, two control signals are used to place the contents of that register on the

bus or to load the data on the bus in to the register.

To transfer the contents of the register R1 to R4

(1)Enable the output of R1 by setting R1out to 1. This places the contents of R1 on the process bus.

(2)Enable the input of Register R4 by setting R4in to 1.This loads data from processor bus in toRegister R4.

52.What is micro programming and micro programmed control unit?

Microprogramming is a method of control unit design in which the control unit selection andsequencing information are stored in ROM and RAMs called control store or control memory.Micro

programmed control unit is a general approach used for implementation of control unit. Here control

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signals are generated by a program similar to machine language programs

53. What is meant by hardwired control? It is the one that contains control units that use fixed logic circuits to interpret instructions and

generate control signals from them.

Here, the fixed logic circuit block includes combinational circuit that generates the requiredcontrol outputs for decoding and encoding functions.

54. What is the necessity of grouping signals?

It is used to reduce the number of the bits in the microinstruction. It is used to overcome the drawback of assigning individual bits to each control signal results in

long microinstructions,because the number of the required signals is usually large,moreoveronly afew bits are used in any given instruction.