Meena's Class Prints: MADRAS UNIVERSITY COMPUTER ARCHITECTURE QUESTION BANK

UNIT-1

1 MARK

1.What is a fixed point and floating point number?

Fixed point representation has fixed number of bits for integer part and for fractional part.
Floating point representation does not reserve a specific number of bits for the integer part or the fractional part.
Instead it reserves a certain number of bits for the number (called the mantissa or significand) and a certain number of bits to say where within that number the decimal place sits (called the exponent).

2.What is a micro operation?

Micro-operations (also known as micro-ops) are the functional or atomic operations of a processor.

3.Define control memory.

Control memory is a random access memory (RAM) consisting of addressable storage registers. It is primarily used in mini and mainframe computers.

4.State the need for address sequencing

Microinstructions are usually stored in groups where each group specifies a routine, where each routine specifies how to carry out an instruction.
Each routine must be able to branch to the next routine in the sequence
.An initial address is loaded into the CAR when power is turned on; this is usually the address of the first microinstruction in the instruction fetch routine.
Next, the control unit must determine the effective address of the instruction

5.Name various data types? Provide examples.

Numbers, Letters, other discrete symbols used for specific purposes.

6.Define a micro operation.

Micro-operations (also known as micro-ops) are the functional or atomic operations of a processor.

7.State the functions of control memory

It directs the flow of data sequence between the processor and other devices.
It can interpret the instructions and controls the flow of data in the processor.
It generates the sequence of control signals from the received instructions or commands from the instruction register.
It has the responsibility to control the execution units such as ALU, data buffers, and registers in the CPU of a computer.
It has the ability to fetch, decode, handle the execution, and store results.
It cannot process and store the data
To transfer the data, it communicates with the input and output devices and controls all the units of the computer.

8.Define data representation.

Computers use binary - the digits 0 and 1 - to store data. A binary digit, or bit, is the smallest unit of data in computing. It is represented by a 0 or a 1. Binary numbers are made up of binary digits (bits), eg the binary number 1001. The circuits in a computer's processor are made up of billions of transistors. A transistor is a tiny switch that is activated by the electronic signals it receives. The digits 1 and 0 used in binary reflect the on and off states of a transistor.

9. What is a bus?

A bus is a high-speed internal connection. Buses are used to send control signals and data between the processor and other components.

10. How a decimal number is converted into its equivalent octal number?

Follow the steps given below to learn the decimal to octal conversion:

Write the given decimal number
If the given decimal number is less than 8 the octal number is the same.
If the decimal number is greater than 7 then divide the number by 8.
Note the remainder, we get after division
Repeat step 3 and 4 with the quotient till it is less than 8
Now, write the remainders in reverse order (bottom to top)
The resultant is the equivalent octal number to the given decimal number.

11. How a floating point number is represented?

A floating-point number is typically expressed in the scientific notation, with a fraction (F), and an exponent (E) of a certain radix (r), in the form of F×r^E.

12. What is a bus?

A bus is a high-speed internal connection. Buses are used to send control signals and data between the processor and other components.

13.What is an instruction?

An instruction is a single operation of a processor defined by the processor instruction set.

14.Give one example for floating point and fixed point data types.

Floating point

4.25 ×101 10-3 -3.35 ×3 -1.42 ×102

Fixed point

2.34 ×103 0.88 ×103

15. What do you mean by micro programmed control? State the basic performance equation of a computer.

The control signals associated with operations are stored in special memory units inaccessible by the programmer as Control Words.
Control signals generated by a program are similar to machine language programs.
Micro-programmed control unit is slower in speed because of the time it takes to fetch microinstructions from the control memory.

16. Write the significance of micro shift operation.

These are used for serial transfer of data. That means we can shift the contents of the register to the left or right. In the shift left operation the serial input transfers a bit to the right most position and in shift right operation the serial input transfers a bit to the left most position.

17.Why do digital computers use binary numbers for their operation?

The circuits in a computer's processor are made up of billions of transistors. A transistor is a tiny switch that is activated by the electronic signals it receives. The digits 1 and 0 used in binary reflect the on and off states of a transistor.

18. What is meant by address sequencing?

Microinstructions are usually stored in groups where each group specifies a routine, where each routine specifies how to carry out an instruction.
Each routine must be able to branch to the next routine in the sequence.
An initial address is loaded into the CAR when power is turned on; this is usually the address of the first microinstruction in the instruction fetch routine.
Next, the control unit must determine the effective address of the instruction

19.List out the different computer instruction formats.

Zero address instruction format
Single address instruction format
Two address instruction format
Three address instruction format

20. What is the role of program counter in addressing?

The program counter, PC, is a special-purpose register that is used by the processor to hold the address of the next instruction to be executed. The PLA automatically updates the PC to point to the next instruction during the op-code decode cycle.

21.Convert the decimal number 61.3 to binary.

Ans 111101.01001100110

22. Give any two tasks which humans can perform better than computers.

Unstructured problem-solving
Non Routine physical work
Acquiring and processing new information, deciding what is relevant in a flood of undefined phenomena

23. What are condition codes?

Condition codes are extra bits kept by a processor that summarize the results of an operation and that affect the execution of later instructions. These bits are often collected together in a single condition or indicator register (CR/IR) or grouped with other status bits into a status register (PSW/PSR).

24.What are the four basic types of operations that need to be supported by an instruction set?

ADD,SUBTRACT,MULTIPLY,DIVIDE

25.What is BCD? ASCII? EBCDIC?

BCD: It is a form of binary encoding where each digit in a decimal number is represented in the form of bits.
This encoding can be done in either 4-bit or 8-bit (usually 4-bit is preferred).
ASCII: Short for American Standard Code for Information Interexchange, ASCII is a standard that assigns letters, numbers, and other characters in the 256 slots available in the 8-bit code.
EBCDIC:EBCDIC, in full extended binary-coded decimal interchange code., Data-encoding system, developed by IBM, that uses a unique eight-bit binary code for each number and alphabetic character as well as punctuation marks and accented letters and non-alphabetic characters.

26. What are data types?

There are four simple data types that represent how information is internally stored in the Platform.
The simple data types in the platform are:
integer
Float
string
character

27. Define control memory.

Control memory is a type of RAM which contains addressable storage registers.
Data is temporarily stored in control memory .
Control memory can be quickly accessed than main memory which speeds up CPU operations

28. List all types of data used in a computer.

Integral, Floating Point, character, Character string and composite types.

29.Write the significance of the arithmetic logic shift unit.

To perform a micro operation, the contents of specified registers are placed in the inputs of the common ALU. The ALU performs an operation and the result of the operation is then transferred to a destination register. The ALU is a combinational circuit, so that the entire register transfer operation from the source registers through the ALU and into the destination register can be performed during one clock pulse period. The shift micro operations are often overall in a separate unit, but sometimes the shift unit is made part of the overall ALU

30.What do you mean by ‘‘Address Sequencing”?

Microinstructions are usually stored in groups where each group specifies a routine, where each routine specifies how to carry out an instruction.
Each routine must be able to branch to the next routine in the sequence
.An initial address is loaded into the CAR when power is turned on; this is usually the address of the first microinstruction in the instruction fetch routine.
Next, the control unit must determine the effective address of the instruction

31. What is the use of Input-Output subsystem?

The input -Output subsystem of a computer ,referred to as I/O, Provides an efficient mode of communication between the central system and the outside environment.

32.What is peripheral?

Input-Output devices attached to the computer are also called peripherals.

33. What are the three types of peripheral?

Input
Output
Input-Output.

34. List out the four peripheral devices that produce an acceptable output for a person to understand.

Printer
Magnetic tape
Magnetic disk
Monitor

35. Define ASCII

ASCII-American Standard Code for Information Interchange
Standard code for alphanumeric character is ASCII
It uses seven bits to code 128 characters
The seven bits of the code are designed by b1 through b7,with b7 being the most significant bit.

36. Define Byte

Computers manipulate an 8 bit quantity as a single unit called a byte.

37.What do you mean by Interface

The word interface is a general term for the point of contact between two parts of a system.

38.What do you mean by I/O command

The function code is referred to as an I/O command and is in essence an instruction that is executed in the interface and its attached peripheral unit.

39.What are the four types of commands that an interface receives

Control
Status
Data output
Data input

40. What do you mean by control command ?

A control command is issued to activate the peripheral and to inform it what to do.

41. What do you mean by Status command

A status command is used to test various status conditions in the interface and the peripheral.

42. What do you mean by data output command

Data output command causes the interface to respond by transferring data from the bus into one of its registers.

43. What do you mean by data input command.

The data input command is the opposite of data output. The interface receives an item of data from the peripheral and places it in its buffer register.

44. What are the three ways that computer buses can be used to communicate with memory and I/O.

Uses two separate memory, one for memory and the other for I/O
Use one common bus for both memory and I/O but have separate control lines for each.
Use one common bus for memory and I/O with common control lines.

44. What do you mean by isolated I/O

The memory read and memory write control lines are enabled during a memory transfer or during an I/O transfer
The configuration that isolates all I/O interface addresses from the addresses assigned to memory and is referred to as the isolated I/O method for assigning addresses in a common bus.

45. What do you mean by isolated I/O

Computers use one common bus to transfer information between memory or I/O and the CPU
The distinction between a memory transfer and I/O transfer is made through separate read and write lines.
The CPU specifies whether the address on the address lines is for a memory word or for an interface register by enabling one of two possible read or write lines.
I/O read and I/O write control lines are enabled during an I/O transfer.
This configuration isolates all I/O interface addresses from the addresses assigned to memory and is referred to as an isolated I/O method for assigning addresses in a common bus.

46.What are the ways that computer can be used to communicate with memory and I/O

Separate set of address, control and data bus to I/O and memory.
Have a common bus (data and address) for I/O and memory but separate control lines.
Have a common bus (data, address, and control) for I/O and memory.

47. What do you mean by memory mapped I/O?

Same address space is used for both memory and I/O.
Computers employ Only one set of read and write signals and do not distinguish between memory and I/O addresses.
This configuration is referred as memory mapped I/O

48. What do you mean by handshaking?

The unit receiving the data item responds with another control signal to acknowledge receipt of the data.
This type of agreement between two independent units is referred to as handshaking.

49.What do you mean by Asynchronous data transfer?

Asynchronous data transfer between the two independent units requires that control signals be transmitted between the communicating units to indicate the time at which data is being transmitted.

50.What do you mean by Polling?

Priority of simultaneous interrupts can be done by software or hardware.
A polling procedure is used to identify the highest priority source by software means.

51. Define DMA

Direct Memory Access (DMA) transfers the block of data between the memory and peripheral devices of the system, without the participation of the processor.
The unit that controls the activity of accessing memory directly is called a DMA controller.

52. What do you mean by cycle stealing?

The DMA module uses the system bus only when the processor does not need it, or it must force the processor to suspend operation temporarily.
The latter technique is more common and is referred to as cycle stealing, because the DMA module in effect steals a bus cycle.

53. How complements are used in data representation and manipulation?

Complements are used in the digital computers in order to simplify the subtraction operation and for the logical manipulations.

54.State the purpose for Bus

A bus is a high-speed internal connection. Buses are used to send control signals and data between the processor and other components.

55. Why address sequencing is done?

Address Sequencing Microinstructions are stored in control memory in groups, with each group specifying a routine. Each computer instruction has its own micro program routine in control memory to generate the micro-operation that executes the instruction.

56.State the components of a CPU

control unit (CU)
arithmetic logic unit (ALU)
Registers.
Cache.
Buses.
Clock.

57. How program counter is employed for? Why?

The program counter, PC, is a special-purpose register that is used by the processor to hold the address of the next instruction to be executed. The PLA automatically updates the PC to point to the next instruction during the op-code decode cycle. By coordinating with other hardware, in addition to the PLA, the PC is automatically incremented as each instruction is executed. The PC can also have an address dictated to it via the 'BRANCH' instruction.

58. What is addressing mode?

The operation field of an instruction specifies the operation to be performed. This operation will be executed on some data which is stored in computer registers or the main memory. The way any operand is selected during the program execution is dependent on the addressing mode of the instruction.

59. What is a vector processor?

A vector processor is a central processing unit that can work on an entire vector in one instruction. The instruction to the processor is in the form of one complete vector instead of its element. Vector processors are used because they reduce the draw and interpret bandwidth owing to the fact that fewer instructions must be fetched.
A vector processor is also known as an array processor.

60. Why asynchronous data transfer is faster/slower? Why?

For asynchronous data transfer, there is no common clock signal between the sender and receivers.
Sending these extra synchronization bits may account for up to 50% data transfer overhead and hence slows down the actual data transfer rate.

61. How interrupt masking is done? Is it advisable?

An interrupt is the automatic transfer of software execution in response to a hardware event that is asynchronous with the current software execution. This hardware event is called a trigger. The hardware event can either be a busy to ready transition in an external I/O device or an internal event; it will request an interrupt by setting its trigger flag.
Interrupts can also be used for infrequent but critical events like power failure, memory faults, and machine errors.
Periodic interrupts will be useful for real-time clocks, data acquisition systems, and control systems.

62. What is MAR and MBR

MAR (memory address register)
MAR specifies the address in memory for the next read/write;
MBR (memory buffer register).
MBR otherwise contains the data to be written into memory, or data to be read from memory.

63. Draw the memory read cycle

64. Name the components of MMU

The MMU consists of a context register, a segment map and a page map.

65. Define RISC and RISC pipeline

RISC, or Reduced Instruction Set Computer. Is a type of microprocessor architecture that utilizes a small, highly-optimized set of instructions, rather than a more specialized set of instructions often found in other types of architectures.
RISC processors, is much like an assembly line. Because the processor works on different steps of the instruction at the same time, more instructions can be executed in a shorter period of time.

66.Name the data types used in computer.

· Boolean (e.g., True or False)

· Character (e.g., a)

· Date (e.g., 03/01/2016)

· Double (e.g., 1.79769313486232E308)

· Floating-point number (e.g., 1.234)

· Integer (e.g., 1234)

· Long (e.g., 123456789)

· Short (e.g., 0)

67. What are the types of buses?

·         Address bus - carries memory addresses from the processor to other components such as primary storage and input/output devices. ...
·         Data bus - carries the data between the processor and other components.
·         Control bus - carries control signals from the processor to other components.

68. Why registers are required when memory is available.

A register temporarily holds frequently used data, instructions, and memory address that are to be used by CPU. ... All data is required to pass through registers before it can be processed. So, they are used by CPU to process the data entered by the users. Registers hold a small amount of data around 32 bits to 64 bits.

69.How space is used in storing partial results?

The cache is used for storing segments of programs currently being executed in the CPU and temporary data frequently needed in the present calculations by making programs and data available.

70.What is an array processor?

In computing, a vector processor or array processor is a central processing unit (CPU) that implements an instruction set containing instructions that operate on one-dimensional arrays of data called vectors, compared to the scalar processors, whose instructions operate on single data items.

71.Multiplication is same as repetitive addition. Is it true? Justify?

Multiplying a x b is same as adding a repeatedly b number of times.
2 + 2 + 2 + 2 =8
2 x 4 =8

72. Why peripheral devices are to be interfaced through proper devices with computer?

The purpose of communication link is to resolve the differences that exist between the central computer and each peripheral.

73. Give an example for Priority interrupt

Devices with high speed transfer such as magnetic disks are given high priority and slow devices such as keyboards are given low priority.
When two or more devices interrupt the computer simultaneously, the computer services the device with the higher priority first.

74. Mention the mode of transfer

Programmed I/O.
Interrupt- initiated I/O.
Direct memory access (DMA).

75.Magnetic disk is a part of memory hierarchy. True/False.

True.

76.What is a multiprocessor?

A multiprocessor is a computer system with two or more central processing units (CPUs), with each one sharing the common main memory as well as the peripherals. This helps in simultaneous processing of programs.

77. Differentiate between arithmetic shift and logical shift right

Logical right shift means shifting the bits to the right and MSB(most significant bit) becomes 0. ... Arithmetic right shift means shifting the bits to the right and MSB(most significant bit) is same as in the original number.

78. Let x=1010100 and y=1000011 are two binary numbers .Find x-y using 2’s complement.

                                 X = 1010100

2's complement of    Y = +0111101

                                        --------------

Sum =                              10010001

Discard end carry Answer: X - Y = 0010001

79.  List the phases of instruction cycle.
There are six fundamental phases of the instruction cycle:

fetch instruction (aka pre-fetch)
Decode instruction.
evaluate address (address generation)
fetch operands (read memory data)
execute (ALU access)
store result (write back memory data)

80. Name any four bit manipulation instructions

Clear
Set
AND
OR
XOR

81. List any four characteristics of RISC processor
1. Memory accesses are restricted to load and store instructions, and data manipulation instructions are register-to-register.
2. Addressing modes are limited in number.
3. Instruction formats are all of the same length.
4. Instructions perform elementary operations

82. What are the three ways to represent a negative integer binary number?

Signed Magnitude Method: In this method, number is divided into two parts: Sign bit and Magnitude. If the number is positive then sign bit will be 0 and if number is negative then sign bit will be 1. Magnitude is represented with the binary form of the number to be represented.
1's Complement Method: Positive numbers are represented in the same way as they are represented in sign magnitude method. If the number is negative then it is represented using 1’s complement. First represent the number with positive sign and then take 1’s complement of that number.
2's Complement Method: Positive numbers are represented in the same way as they are represented in sign magnitude method. If the number is negative then it is represented using 2’s complement. First represent the number with positive sign and then take 2’s complement of that number.

83. What is BCD adder?

The BCD-Adder is used in the computers and the calculators that perform arithmetic operation directly in the decimal number system. The BCD-Adder accepts the binary-coded form of decimal numbers. The Decimal-Adder requires a minimum of nine inputs and five outputs.

84. What is memory mapped I/O?

In this case every bus in common due to which the same set of instructions work for memory and I/O. Hence we manipulate I/O same as memory and both have same address space, due to which addressing capability of memory become less because some part is occupied by the I/O.

85. What are handshaking signals?

The microprocessor and different I/O devices operate at different speeds. For this reason, signals are exchanged between the first responding MPU and slow responding I/O devices prior to data transfer. These signals are called handshake signals.

86. What is associate memory?

An associative memory can be considered as a memory unit whose stored data can be identified for access by the content of the data itself rather than by an address or memory location.

87. How many 128 X 8 RAM chips are needed to provide a memory capacity of 2048 bytes?

8 bits = 1 byte, Each RAM chip has 64 x 1 byte = 64 bytes. Thus the number of chips to address a memory capacity of 2048 bytes will be, 2048/64 = 32 chips.

88. What do you mean by micro operations?

The operations executed on data stored in registers are called micro operations.

89. What do you mean by Register Transfer Logic?

The symbolic notation used to describe the micro operation transfers among registers is called a register transfer language.

90. What do you mean by Common Bus?

Scheme for transferring information between registers in a multiple register configuration is a common bus system.

91.What are the four categories of micro operations?

Register transfer micro operations transfer binary information from one register to another
Arithmetic micro operations perform arithmetic operation on numeric data stored in registers.
Logic micro operations perform bit manipulation operations on non numeric data stored in registers.
Shift micro operations perform shift operations on data stored in registers.

92. What do you mean by full adder?

The digital circuit that forms the arithmetic sum of two bits and a previous carry is called a full-adder.

93. What do you mean by binary adder?

The digital circuit that generates the arithmetic sum of two binary numbers of any lengths is called a binary adder.

94. What are the three types of shift?

Logical
Circular
Arithmetic

95. What do you mean by Logical shift?

A logical shift is one that transfers 0 through the serial input.

96. What do you mean by Circular shift?

The circular shift circulates the bits of the register around the two ends without loss of information.

97. What do you mean by arithmetic shift?

An arithmetic shift is a micro operation that shifts a signed binary number to the left or right.

98. What do you mean by ALU?

Instead of having individual registers performing the micro operations directly, computer systems employ a number of storage registers connected to a common operational unit called an Arithmetic Logic unit. The ALU performs an operation and the result of the operation is then transferred to a destination register.

5 MARK

Explain RTL, with examples
Write with examples, on memory transfer operation.
What is an accumulator?
How floating point numbers are represented using binary codes? Illustrate.
What are the shift micro operations? Explain with examples.
Explain address sequencing.
Explain how binary codes are used in representing floating point data.
Describe the register transfer? How data gets transferred?
Write the purposes for general register assembly
What is an instruction cycle? Explain.
Write the principles of RTL, with an example.
What is control memory? Explain the actions.
Explain about the register transfer concept with example.
How will you design the control unit?
Mention the data transfer and manipulation in the central processing unit.
Describe the basic concepts of memory transfer
Explain register transfer logic (RTL) and illustrate various micro operations.
Describe various instruction formats, with example.
Explain about the control unit with its design.
Write short notes about ‘‘micro operations and micro program”.
Explain various data representation schemes.
Briefly explain few micro operations with examples.
What is control memory?. Explain
Why do addressing modes required?. Explain.
Explain the subtraction of two floating point numbers.
Describe the effect of DMA on CPU
Enumerate interconnection structures and compare.
Explain data types and representation used in computer
Describe register transfer schemes and in RTL
Describe RISC and Pipeline
How multiplication of floating point number is performed ?Illustrate an algorithm?
Explain different data transfer schemes
Discuss the importance of serial communication
Explain the concept of associative memory.
Design a 4 bit adder-subtractor using full adders and Explain
Explain various shift instructions each with an example.
Illustrate various instruction formats in detail.
Derive an algorithm in flowchart form for addition and subtraction of two signed integer numbers.
With the help of block diagram, Explain the Daisy chaining method of establishing priority among the devices.
Describe the block diagram of associate memory and show the Boolean function for the match of one word in an associate memory.
Draw the 8 X 8 omega switching network and Explain the data transfer between source to destination in that network.

10 MARK

Explain various instruction groups, and illustrate with examples.
Explain the micro programmed control unit and how it sequences the addresses.
Explain the working of a micro programmed control unit, with a block diagram.
What is an instruction? Give its format? How are they classified? Illustrate with examples.
Describe the micro programmed control, with address sequencing.
Explain various codes and how they are used in data representation.
What is a micro operation? Explain arithmetic logic and shift micro operations.
Explain address sequencing and the design of control unit.
With one example, explain about arithmetic, logic and shift micro operation.
Explain in detail about register transfer logic, with suitable examples.
Describe the basic concepts of Arithmetic logic shift unit.
Draw the single bus on three bus organizations of the data path inside a processor.
Explain the data representation? Convert (1832.64)10 into equivalent binary, octal and hexadecimal members.
Describe address sequencing with a micro program control unit.
Discuss in detail about the address sequencing systems, with example.
Describe arithmetic ,Logic and shift micro operations with sample data.
Explain instruction formats and illustrate any four with examples
Describe arithmetic and instruction pipeline schemes with illustration.
Explain I/O organization and how I/O devices handshake with CPU
Describe virtual memory concept and implementation issues.
Writs short notes on :

a) Address sequencing

b) Inter processor arbitration.

22. Describe the ALU and the operations performed in this unit ,with relevant examples.

23. Explain a micro program control unit and how this processes micro program.

24. Describe various formats of instruction and how they are classified? Illustrate one instruction in each group.

25.Explain how priorities are handled? Write the sequence of operations upon the receipt of an interrupt.

26.Discuss the operations of memory device used in memory hierarchy.

27.Write short notes on:

a) Decimal arithmetic operations

b) Interconnection structures.

28.Describe the steps involved during address sequencing in a micro-program control unit and also explain the selection of address for control memory with the help of diagram.

29. Explain various addressing modes in detail.

30. Explain an instruction an cycle in the CPU can be processed with four-segment pipeline and also show the timing of instruction pipeline.

31. Give the Booth algorithm for multiplication of two binary numbers and illustrate with an example. Also show the hardware requirements to implement the algorithm

32. What is DMA? Explain DMA transfer in a computer system with the help of block diagram.

33.What is cache memory? Explain various mapping procedures used in cache memory organization with their relative advantages and disadvantages.

34. Describe the steps involved during address sequencing in a micro-program control unit and also explain the selection of address for control memory with the help of diagram

35. Explain various addressing modes in detail.

36. Explain an instruction cycle in the CPU can be processed with four segment pipeline and also show the timing of instruction pipeline.

37. Give the Booth algorithm for multiplication of two binary numbers and illustrate with an example. Also show the hardware requirements to implement the algorithm.

38. What is DMA?. Explain DMA transfer in a computer system with the help of block diagram.

39. What is cache memory?. Explain various mapping procedure used in cache memory organization with their relative advantages and disadvantages.

Meena's Class Prints

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MADRAS UNIVERSITY COMPUTER ARCHITECTURE QUESTION BANK

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