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CS1251   COMPUTER ARCHITECTURE
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UNIT I:BASIC STRUCTURE OF COMPUTER


Part – A( 2Marks)
1. What is meant by the stored program concept?
2. What are the basic functional units of a computer?
3. What is the use of buffer register?
4. Define memory access time.
5. Write the differences between RISC and CISC.
6. What is meant by MAR and MDR?
7. What is an interrupt?
8. Why data bus is bidirectional in most microprocessors?
9. What do you mean by multiprogramming or multitasking?
10. Give the basic performance equation.
11. What are the limitations of assembly language?
12. What are the two techniques used to increase the clock rate R?
13. What are big-endian and little-endian representations?
14. What is the information conveyed by addressing modes?
15. What are the different types of addressing modes available?
16. What is indirect addressing mode?
17. What is indexed addressing mode?
18. Define auto increment mode of addressing?
19. Define auto decrement mode of addressing?
20. What are condition code flags?
21. What is the use of assembler directive?
22. What is meant by straight – line sequencing?
23. What is stack?
24. Which data structure is best supported using indirect addressing mode?
25. What are the differences between Stack and Queue?
Part – B
1. Explain the basic functional units of a simple computer. (8)
2. Explain the basic I/O operations of modern processors. (8)
3. Explain various addressing modes found in modern processors (16)
4. Explain various assembler directives used in assembly language program (8)
5. What are stack and queues? Explain its use and give its differences (10)
6. What are the various types of ISAs possible? Discuss. (8)
7. Discuss the various issues to be considered while designing the ISA of a processor.(8)




UNIT II:ARITHMETIC UNIT


Part - A( 2Marks)
1. Draw the full adder circuit using two half adders and give the truth table.
2. Why floating point number is more difficult to represent and process than integer?
3. What are the two approaches used to reduce delay in adders?
4. What is a carry look-ahead adder?
5. Discuss the principle behind the Booth’s algorithm?
6. How can we speed up the multiplication process?
7. What is bit pair recoding? Give an example.
8. What are the two methods of achieving the 2’s complement?
9. What is the advantage of using Booth algorithm?
10. Write the algorithm for restoring division.
11. Write the algorithm for non restoring division.
12. Define IEEE floating point single and double precision standard.
13. When can you say that a number is normalized?
14. Explain about the special values in floating point numbers.
15. Write the Add/subtract rule for floating point numbers.
16. Write the multiply rule for floating point numbers.
17. What is the purpose of guard bits?
18. What are the ways to truncate the guard bits?
19. Define carry save addition (CSA) process.
20. What are generated and propagate function?
21. What is excess-127 format?
22. What is a ripple carry adder?
23. Draw the structure of 4-bit MSI ALU circuit block.
24. What are the various ways of representing signed integers in the system?
25. Give the booth’s recoding and bit pair recoding of the number 1000011100100101.
Part – B
1. Discuss the principle of operation of carry-look ahead adders. (8)
2. Discuss the non-restoring division algorithm. Simulate the same for 23/5. (8)
3. Multiply the following pair of signed 2’s complements numbers using bit pair recoded
multiplier: Multiplicand = 110011 Multiplier = 101100. (8)
4. With a neat sketch, Explain in detail about logic design for fast adders. (16)
5. Describe how the floating-point numbers are represented and used in digital arithmetic operations. Give an example. (16)
6. Explain the representations of floating point numbers in detail. (6)
7. Design a multiplier that multiplies two 4-bit numbers. (6)
8. Give the block diagram of the hardware implementation of addition and subtraction ofsigned number and explain its operations. (10)
9. Explain the working of floating point adder and subtractor. (10)




UNIT III:BASIC PROCESSING UNIT


Part – A( 2Marks)
1. What are the limitations of super scalar device?
2. Define pipeline speedup.
3. What is a processor clock?
4. Write down the control sequence for Move (R1), R2.
5. What is the function of a TLB (translation look-aside buffer)?
6. What is the WMFC step needed when reading from or writing to the main memory?
7. Define register file.
8. Define the hardware organization of two-stage pipeline?
9. What is the role of cache memory in pipeline?
10. Name the methods for generating the control signals.
11. Define hardwired control.
12. Discuss the principle of operation of a micro programmed control.
13. Differentiate micro programmed control from hardwired control.
14. Define parallelism in microinstruction.
15. What are the types of microinstructions available?
16. Differentiate horizontal microinstruction from vertical microinstruction.
17. What is MFC?
18. What are the major characteristics of a pipeline?
19. What is a pipeline hazard?
20. What is data hazard?
21. What is instruction or control hazard?
22. Define structural hazards.
23. What is side effect?
24. What do you mean by branch penalty?
25. What is branch folding?
26. What do you mean by delayed branching?
27. What are the two types of branch prediction techniques available?
28. What is the ideal speedup expected in a pipelined architecture with n stages. Justify your answer.
29. Draw the structure of two stage instruction pipeline.
Part – B
1. Give the organization of typical hardwired control unit and explain the functions
performed by the various blocks. (16)
2. Discuss the various hazards that might arise in a pipeline. What are the remedies commonly adopted to overcome/minimize these hazards. (16)
3. Explain in detail about instruction execution characteristics. (16)
4. With a neat block diagram, explain in detail about micro programmed control unit and explain its operations. (16)
5. Explain the execution of an instruction with diagram. (8)
6. Explain the multiple bus organization in detail. (8)
7. Explain the function of a six segment pipeline showing the time it takes to process eight tasks. (10)
8. Highlight the solutions of instruction hazards. (6)
9. Explain the instruction cycle highlighting the sub-cycles and sequence of steps to be followed. (8)




UNIT IV:MEMORY SYSTEM


Part – A( 2Marks)
1. Define Memory Access time for a computer system with two levels of caches.
2. How to construct an 8M * 32 memory using 512 K * 8 memory chips.
3. Write two advantages of MOS device.
4. List the factors that determine the storage device performance.
5. What will be the width of address and data buses for a 512K * 8 memory chip?
6. Define memory cycle time.
7. What is RAM?
8. What is cache memory?
9. Explain virtual memory.
10. List the various semiconductors RAMs?
11. What do you mean by static memories?
12. Define DRAM’s.
13. Define DDR SDRAM.
14. What is ROM?
15. What is the mapping procedures adopted in the organizatio n of a cache Memory?
16. Give the format for main memory address using direct mapping function for 4096 blocks
in main memory and 128 blocks in cache with 16 blocks per cache.
17. Give the format for main memory address using associative mapping function for 4096
blocks in main memory and 128 blocks in cache with 16 blocks per cache.
18. Give the format for main memory address using set associative mapping function for 4096 blocks in main memory and 128 blocks in cache with 16 blocks per cache.
19. Define Hit and Miss rate?
20. What are the enhancements used in the memory management?
21. What is meant by memory management unit?
22. What is meant by memory interleaving?
23. What do you mean by seek time?
24. What is disk controller?
25. What is RAID?
26. Define data stripping?
27. How the data is organized in the disk?
28. Define latency time.
29. What is the significance of TLB?
Part – B
1. Discuss the various mapping techniques used in cache memories. (8)
2. A computer system has a main memory consisting of 16 M words. It also has a 32Kword cache organized in the block-set-associative manner, with 4 blocks per set and 128 words per block.
1. Calculate the number of bits in each of the TAG, SET and WORD fieldsof the main memory address format.
2. How will the main memory address look like for a fully associative
mapped cache? (8)
3. Explain the concept of virtual memory with any one virtual memory management technique. (8)
4. Give the basic cell of an associative memory and explain its operation. Show how associative memories can be constructed using this basic cell. (8)
5. Give the structure of semiconductor RAM memories. Explain the read and write operations in detail. (16)
6. Explain the organization of magnetic disks in detail. (8)
7. A digital computer has a memory unit of 64K*16 and a cache memory of 1K words.The cache uses direct mapping with a block size of four words. How many bits are there in the tag, index, block and word fields of the address format? How many blocks can the caches accommodate? (10)
8. Explain the concept of memory hierarchy. (6)




UNIT V:I/O ORGANIZATION

Part – A( 2Marks)
1. What are the functions of I/O interface?
2. How does the processor handle an interrupt request?
3. What are the necessary operations needed to start an I/O operation using DMA?
4. What are the three types of channel usually found in large computers?
5. Why does a DMA have priority over the CPU when both request a memory transfer?
6. What is the advantage of using interrupt initiated data transfer?
7. Why do you need DMA?
8. What is the difference between subroutine and interrupt service routine?
9. What is the need for interrupt masks?
10. How does bus arbitration typically works?
11. How does a processor handle an interrupt?
12. Distinguish synchronous bus and asynchronous bus.
13. Why I/O devices cannot be directly be connected to the system bus?
14. What are the major functions of I/O system?
15. What is an I/O interface?
16. Write the factors considered in designing an I/O subsystem?
17. Explain Direct Memory Access.
18. Define DMA controller.
19. What is polling?
20. What is the need of Interrupt controller?
21. What is a priority interrupt?
22. Define bus.
23. Define synchronous bus.
24. Define asynchronous bus.
25. State the differences between memory mapped I/O and I/O mapped I/O.
26. Define interrupt.
27. Define exception.
28. What are the different methods used for handling the situation when multiple interrupts
occurs?
29. What is a privileged instruction?
30. What is bus arbitration?
31. What is port? What are the types of port available?
32. What is a parallel port?
33. What is a serial port?
34. What is PCI bus?
35. What is SCSI?
36. Define USB.
Part – B
1. Explain the functions to be performed by a typical I/O interface with a typical input output
interface. (16)
2. Discuss the DMA driven data transfer technique. (8)
3. Discuss the operation of any two input devices (8)
4. Explain in detail about interrupt handling. (16)
5. Explain in detail about standard I/O interface. (16)
6. Describe the functions of SCSI with a neat diagram. (16)
7. What is the importance of I/O interface? Compare the features of SCSI and PCI
interfaces. (8)
8. Write note on the following.
1. Bus arbitration
2. Printer process communication
3. USB
4. DMA (16)
9. Explain the use of vectored interrupts in processes. Why is priority handling desired in interrupt controllers? How does the different priority scheme work? (8)


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TLW Two mark Questions from Rectangular Waveguide

Two mark questions collected from FAQ papers ,provided with relevant answers to help you easy understand.Problem in viewing or feel difficulty? leave your comment.Let us know what to do.

TWO MARK QUESTIONS AND ANSWERS
UNIT V

RECTANGULAR WAVEGUIDE

  1. Why is circular or rectangular form used as waveguide?
Waveguides usually take the form of rectangular or circular cylinders because of its simpler forms in use and less expensive to manufacture.

  1. What is an evanescent mode?
When the operating frequency is lower than the cut-off frequency, the propagation constant becomes real i.e., γ= α . The wave cannot be propagated. This non- propagating mode is known as evanescent mode.

  1. What is the dominant mode for the TE waves in the rectangular waveguide?
The lowest mode for TE wave is TE10 (m=1 , n=0)

  1. What is the dominant mode for the TM waves in the rectangular waveguide?
The lowest mode for TM wave is TM11(m=1 , n=1)

  1. What is the dominant mode for the rectangular waveguide?
The lowest mode for TE wave is TE10 (m=1 , n=0) whereas the lowest mode for TM wave is TM11(m=1 , n=1). The TE10 wave have the lowest cut off frequency compared to the TM11 mode. Hence the TE10 (m=1 , n=0) is the dominant mode of a rectangular waveguide.Because the TE10 mode has the lowest attenuation of all modes in a rectangular waveguide and its electric field is definitely polarized in one direction everywhere.

  1. Which are the non-zero field components for the for the TM11 mode in a
rectangular waveguide?
Hx, Hy ,Ey. and Ez.

  1. Define characteristic impedance in a waveguide
The characteristic impedance Zo can be defined in terms of the voltage-current ratio or in terms of power transmitted for a given voltage or a given current.
Zo (V,I) = V/I

  1. Why TEM mode is not possible in a rectangular waveguide?
Since TEM wave do not have axial component of either E or H ,it cannot
propagate within a single conductor waveguide


  1. Explain why TM01 and TM10 modes in a rectangular waveguide do not exist.
For TM modes in rectangular waveguides, neither m or n can be zero because all the field equations vanish ( i.e., Hx, Hy ,Ey. and Ez.=0). If m=0,n=1 or m=1,n=0 no fields are present. Hence TM01 and TM10 modes in a rectangular waveguide do not exist.

  1. What are degenerate modes in a rectangular waveguide?
Some of the higher order modes, having the same cut off frequency , are
called degenerate modes. In a rectangular waveguide , TEmn and TMmn modes ( both m _ 0 and n _ 0) are always degenerate.

CIRCULAR WAVEGUIDES AND CAVITY RESONATORS

  1. What is a circular waveguide?
A circular waveguide is a hollow metallic tube with circular crosssection
for propagating the electromagnetic waves by continuous reflections from
the surfaces or walls of the guide

  1. Why circular waveguides are not preferred over rectangular waveguides?
The circular waveguides are avoided because of the following reasons:

a) The frequency difference between the lowest frequency on the dominant
mode and the next mode is smaller than in a rectangular waveguide, with
b/a= 0.5
b) The circular symmetry of the waveguide may reflect on the possibility of
the wave not maintaining its polarization throughout the length of the
guide.
c) For the same operating frequency, circular waveguide is bigger in size
than a rectangular waveguide.

  1. Mention the applications of circular waveguide.
Circular waveguides are used as attenuators and phase-shifters

  1. Which mode in a circular waveguide has attenuation effect decreasing with
increase in frequency?
TE01

  1. What are the possible modes for TM waves in a circular waveguide?
The possible TM modes in a circular waveguide are : TM01 , TM02 ,
TM11, TM12

  1. What are the root values for the TM modes?
The root values for the TM modes are:
(ha)01 = 2.405 for TM01
(ha)02 = 5.53 for TM02
(ha)11 = 3.85 for TM11
(ha)12 = 7.02 for TM12

  1. Define dominant mode for a circular waveguide.
The dominant mode for a circular waveguide is defined as the lowest
order mode having the lowest root value.


  1. What are the possible modes for TE waves in a circular waveguide?
The possible TE modes in a circular waveguide are : TE01 , TE02 ,
TE11, TE12

  1. What are the root values for the TE modes?
The root values for the TE modes are:
(ha)01 = 3.85 for TE01
(ha)02 = 7.02 for TE02
(ha)11 = 1.841 for TE11
(ha)12 = 5.53 for TE12

  1. What is the dominant mode for TE waves in a circular waveguide
The dominant mode for TE waves in a circular waveguide is the
TE11 because it has the lowest root value of 1.841

  1. What is the dominant mode for TM waves in a circular waveguide
The dominant mode for TM waves in a circular waveguide is the
TM01 because it has the lowest root value of 2.405.

  1. What is the dominant mode in a circular waveguide
The dominant mode for TM waves in a circular waveguide is the
TM01 because it has the root value of 2.405. The dominant mode for TE waves in
a circular waveguide is the TE11 because it has the root value of 1.841 .Since the
root value of TE11 is lower than TM01 , TE11 is the dominant or the lowest order
mode for a circular waveguide.

  1. Mention the dominant modes in rectangular and circular waveguides
For a rectangular waveguide,
the dominant mode is TE01
For a circular waveguide,
the dominant mode is TE11

  1. Why is TM01 mode preferred to the TE01 mode in a circular waveguide?
TM01 mode is preferred to the TE01 mode in a circular waveguide, since
it requires a smaller diameter for the same cut off wavelength.

  1. What are the performance parameters of microwave resonator?
The performance parameters of microwave resonator are:
(i) Resonant frequency
(ii) Quality factor
(iii) Input impedance

  1. What is resonant frequency of microwave resonator?
Resonant frequency of microwave resonator is the frequency at which the energy in the resonator attains maximum value. i.e., twice the electric energy or magnetic energy.


  1. Define quality factor of a resonator.
The quality factor Q is a measure of frequency selectivity of the resonator.
It is defined as
Q = 2 π x Maximum energy stored / Energy dissipated per cycle
= ω W/ P
Where W is the maximum stored energy
P is the average power loss

  1. What is a resonator?
Resonator is a tuned circuit which resonates at a particular frequency at
which the energy stored in the electric field is equal to the energy stored in the magnetic field.

  1. How the resonator is constructed at low frequencies?
At low frequencies upto VHF ( 300 MHz) , the resonator is made up of
the reactive elements or the lumped elements like the capacitance and the inductance.

  1. What are the disadvantages if the resonator is made using lumped elements at high frequencies?
1) The inductance and the capacitance values are too small as the
frequency is increased beyond the VHF range and hence difficult to
realize .

  1. What are the methods used for constructing a resonator?
The resonators are built by
a) using lumped elements like L and C
b) using distributed elements like sections of coaxial lines
c) using rectangular or circular waveguide

32. What is a transmission line resonator or coaxial resonator?
Transmission line resonator can be built using distributed elements like
sections of coaxial lines. The coaxial lines are either opened or shunted at the end
sections thus confining the electromagnetic energy within the section and acts as the resonant circuit having a natural resonant frequency.

  1. Why transmission line resonator is not usually used as microwave resonator?
At very high frequencies transmission line resonator does not give very
high quality factor Q due to skin effect and radiation loss. So, transmission line resonator is not used as microwave resonator.

  1. What are cavity resonators?
Cavity resonators are formed by placing the perfectly conducting sheets on
the rectangular or circular waveguide on the two end sections and hence all the sides are surrounded by the conducting walls thus forming a cavity. The electromagnetic energy is confined within this metallic enclosure and they acts as resonant circuits .
  1. What are the types of cavity resonators?
There are two types of cavity resonators. They are:
a ) Rectangular cavity resonator
b ) Circular cavity resonator

  1. Why rectangular or circular cavities can be used as microwave resonators?
Rectangular or circular cavities can be used as microwave resonators because they have natural resonant frequency and behave like a LCR circuit.

  1. How the cavity resonator can be represented by a LCR circuit?
The electromagnetic energy is stored in the entire volume of the cavity in
the form of electric and magnetic fields. The presence of electric field gives rise to a capacitance value and the presence of magnetic field gives rise to a inductance value and the finite conductivity in the walls gives rise to loss along the walls giving rise to a resistance value. Thus the cavity resonator can be represented by a equivalent LCR circuit and have a natural resonant frequency.

  1. Name the three basic configurations of coaxial resonators.
The basic configurations of coaxial resonators are:
d) Quarter wave coaxial cavity
e) Half wave coaxial cavity
f) Capacitance end coaxial cavity

39. What is the dominant mode for rectangular resonator?
The dominant mode of a rectangular resonator depends on the
dimensions of the cavity.
For b<a<d, the dominant mode is TE101.

  1. What is the dominant mode for circular resonator?
The dominant mode of a circular resonator depends on the dimensions
of the cavity. Ford< 2a, the dominant mode is TM010

  1. When a medium is said to be free- space.
A free-space medium is one in which there are no conduction currents and no charges.

  1. Which are the non-zero field components for the for the TE10 mode in a rectangular waveguide?

Hx, Hz and Ey.

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