02 - Computer architecture, Study notes of Computer science

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Computer Architecture 13

Input Unit

The computer accepts coded information through input unit by the user. It is a device that is used to give required information to the computer. e.g. Keyboard, mouse, etc.

An input unit performs the following functions

(i) It accepts the instructions and data from the user. (ii) It converts these instructions and data in computer in acceptable format. (iii) It supplies the converted instructions and data to the computer system for further processing.

Output Unit

This unit sends the processed results to the user. It is mainly used to display the desired result to the user as per input instruction. e.g. Monitor, printer, plotter, etc.

The following functions are performed by an output unit

(i) It accepts the results produced by the computer which are in coded form and hence cannot be easily understood by user. (ii) It converts these coded results to human acceptable form. (iii) It supplies the converted results to the user.

Central Processing

Unit (CPU)

It consists a set of registers, arithmetic logic unit and control unit, which together interpret and execute instructions in assembly language.

The primary functions of the CPU are as follows

(i) The CPU transfers instructions and input data from main memory to registers, i.e. internal memory. (ii) The CPU executes the instructions in the stored sequence. (iii) When necessary, CPU transfers output data from registers to main memory.

Central Processing Unit is often called the brain of computer. The CPU is fabricated as a single Integrated Circuit (IC) and is also known as microprocessor. A CPU controls all the internal and external devices and performs arithmetic and logic operations. The CPU consists of following main sub-systems

Arithmetic Logic Unit (ALU) ALU contains the electronic circuitry that executes all arithmetic and logical operations on the available data. ALU uses registers to hold the data that is being processed. Most ALUs can perform the following operations (i) Logical operations (AND, NOT, OR, XOR). (ii) Arithmetic operations (addition, subtraction, multiplication and division). (iii) Bit-shifting operations (shifting or rotating a word by a specified number of bit to the left or right with or without sign extension). (iv) Comparison operations (=, <, < =, >, > =)

Registers

These are used to quickly accept, store and transfer data and instructions that are being used immediately by the CPU. These registers are the top of the memory hierarchy and are the fastest way for the system to manipulate data. The number and size of registers vary from processor to processor.

Control Unit (CU) CU coordinates with the input and output devices of a computer. It directs the computer to carry out stored program instructions by communicating with the ALU and the registers. It organises the processing of data and instructions. The basic function of control unit is to fetch the instruction stored in the main memory, identify the operations and the devices involved in it and accordingly generate control signals.

14 Learn, Revise & Practice ~^ Computer Awareness

Microprocessor

It is the controlling element in a computer system and is sometimes referred to as the chip. Microprocessor is the main hardware that drives the computer. It is a large Printed Circuit Board (PCB), which is used in all electronic systems such as computer, calculator, digital system, etc. The speed of CPU depends upon the type of microprocessor used. n (^) Intel 4004 was the first microprocessor made by Intel in 1971 by scientist Ted Hoff and engineer Frederico Faggin. n (^) Some of the popular microprocessors are Intel, Intel core i7, Dual core, Pentium IV, etc.

Memory Unit

This unit is responsible to store programs or data on a temporary or permanent basis. It has primary memory (main memory) and secondary memory (auxiliary memory).

The input data which is to be processed is brought into main memory before processing.

Another kind of memory is referred to as secondary memory of a computer system. This unit is used to permanently store data, programs and output. This unit does not deal directly with CPU.

Motherboard

The main circuit board contained in any computer is called a motherboard. It is also known as the main board or logic board or system board or planar board. All the other electronic devices and circuits of computer system are attached to this board like, CPU, ROM , RAM, expansion slots, PCI slots and USB ports. It also includes controllers for devices like the hard drive, DVD drive, keyboard and mouse. In other words, motherboard makes everything in a computer work together.

Components on

Motherboard

Various components on motherboard are as follows

(i) CMOS Battery (ii) BIOS Chip (iii) Fan (iv) Expansion Slot (v) SMPS (vi) PCI Slot (vii) Processor Chip (viii) Buses

Interconnection of Units

CPU sends data, instructions and information to the components inside the computer as well as to the peripheral devices attached to it. A bus is a set of wires used for interconnection, where each wire can carry one bit of data. In other words, bus is a set of electronic signal pathways that allows information and signals to travel between components inside or outside of a computer. A computer bus can be divided into two types

1. Internal Bus The internal bus connects components inside the motherboard like CPU and system memory. It is also called the system bus. Internal bus includes following buses (i) The command to access the memory or the I/O devices is carried by the control bus. (ii) The address of I/O devices or memory is carried by the address bus. The data to be transferred is carried by the data bus.
2. External Bus It connects the different external devices; peripherals, expansion slots, I/O ports and drive connections to the rest of computer. It is also referred to as the expansion bus.

n (^) UPS (Uninterruptible Power Supply), is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails. n (^) Buffer is a temporary storage where register holds the data for further execution. n (^) Accumulator is a register in a CPU in which intermediate arithmetic and logic results are stored. n (^) An uniform interval of CPU time allocated for use in performing a task is known as time slice. n (^) The speed of processor is measured in millions of cycles per second or megahertz (MHz) by clock speed. n (^) DMA (Direct Memory Access) is a method that allows an input/output device to send or receive data directly to or from the main memory, by passing the CPU to speed up memory operations.

Tit-Bits

7. The components that process data are

located in which of the following? [IBPS Clerk Mains 2017] (1) Input devices (2) Output devices (3) System unit (4) Storage component (5) Expansion board

8. Which of the following is not responsible

for the performance of the computer? [IBPS Clerk Mains 2017] (1) number of keys in the keyboard (2) format of the video/graphics word (3) memory in the video/graphics word (4) the clock speed of the processor (5) number of cores available in the processor

9. A(n) ......... device is any device that provides

information, which is sent to the CPU. (1) input (2) output (3) CPU (4) memory

10. Which of the following includes as a type of

input? (1) data (2) programs (3) commands (4) user response (5) All of these

11. Information that comes from external

source and fed into computer software is called. [IBPS RRB PO Mains 2017] (1) Output (2) Input (3) Throughout (4) Reports (5) Process

12. Input unit converts data in computer in ........

(1) suitable (2) acceptable (3) understandable (4) rejectable

13. This unit sends the processed results to the

user. (1) Input (2) Output (3) Memory (4) CPU

14. Output unit includes

(1) plotter (2) printer (3) monitor (4) All of these

15. This component is required to process data

into information and consists of integrated circuits. [SBI Clerk 2011] (1) Hard disk (2) RAM (3) CPU (4) ROM (5) None of these

16. The Central Processing Unit (CPU) in a

computer consists of (1) input, output and processing (2) control unit, primary storage and secondary storage (3) control unit, arithmetic logic unit, memory unit (4) All of the above

17. Which instruction is used for loading data

into CPU accumulator register from memory? (1) Load (2) Storage (3) Machine (4) Access

18. Where does computer add and compare data?

(1) Hard disc (2) Floppy disc (3) CPU chip (4) Memory chip

19. What is the brain of the computer?

[SSC CGL 2016] (1) Keyboard (2) Mouse (3) CPU (4) Printer

20. CPU is fabricated as a single integrated

circuit which is known as (1) Motherboard (2) Microprocessor (3) ALU (4) CU

21. The CPU chip used in a computer is

partially made of (1) copper (2) iron (3) gold (4) silica

22. The main job of a CPU is to

(1) carry out program instructions (2) store data/information for further use (3) process data and information (4) Both 1 and 3

23. The main purpose of time-sharing

techniques used in computers is to make the best use of the (1) CPU (2) peripherals (3) secondary storage (4) floppy discs

24. The CPU is made up of two smaller

components (1) ALU and CU (2) ALU and RAM (3) RAM and ROM (4) RAM and CUz

25. The CPU comprises of control, memory and

..... units. [SBI PO 2013] (1) microprocessor (2) arithmetic/logic (3) output (4) ROM (5) input

16 Learn, Revise & Practice ~^ Computer Awareness

26. What is the responsibility of the logical unit

in the CPU of a computer? [IBPS Clerk 2015] (1) To produce result (2) To compare numbers (3) To control flow of information (4) To do Maths work (5) None of the above

27. Which unit of computer helps in

communication between the memory and the arithmetic logical unit? [IBPS RRB PO Mains 2017] (1) CMU (2) CCU (3) UPS (4) CPU (5) ALU

28. Which part of the computer is used for

calculating and comparing? [IBPSClerk2013] (1) ALU (2) Control unit (3) Disc unit (4) Modem (5) None of these

29. Pick the one that is used for logical

operations or comparisons such as less than, equal to or greater than etc. (1) ALU (2) CU (3) Input unit (4) MU

30. What does ALU in computing denote?

[IBPS Clerk 2014] (1) Application and Logic Unit (2) Algorithm Logic Unit (3) Arithmetic Layered Unit (4) Arithmetic Legal Unit (5) Arithmetic Logic Unit

31. How many types of arithmetic operations

does the ALU of computer perform? (1) 4 (2) 2 (3) 5 (4) 8

32. Processors contain a control unit and a/an :

(1) Control unit [SSC CGL 2016] (2) Primary storage unit (3) Input unit (4) Arithmetic logic unit

33. Which of the following executes the

computer commands? (1) Arithmetic unit (2) Logic unit (3) Both ‘1’ and ‘2’ (4) Control unit

34. Which unit is a combinational digital

electronic circuit that performs arithmetic and bitwise operations on integer binary numbers? [IBPS RRB PO Mains 2017] (1) BOU (2) AEU (3) CPU (4) ALU (5) UPS

35. Internal memory in a CPU is nothing but

(1) a set of registers (2) a set of ALU (3) microprocessor (4) bus

36. Which among the following is a small set of

data holding place that is a part of the computer processor and may hold an instruction, a storage address, or any kind of data? [IBPS RRB PO Mains 2017] (1) Register (2) WAN (3) Bus (4) Address (5) Processor

37. The portion of the CPU that coordinates the

activities of all the other computer components is the [SBI PO 2015] (1) motherboard (2) coordination board (3) control unit (4) arithmetic logic unit (5) None of these

38. Which among the following is an important

circuitry in a computer system that directs the operation of the processor? [IBPS PO 2016] (1) Memory (2) Address Bus (3) Accumulator (4) ALU (5) Control unit

39. The part of a computer that coordinates all

its functions, is called its [IBPS Clerk Mains 2017] (1) ROM program (2) System board (3) Arithmetic logic unit (4) Control unit (5) None of these

40. The control unit controls other units by

generating [IBPS Clerk 2011] (1) control signal (2) timing signal (3) transfer signal (4) command signal

41. Control unit of a digital computer is often

called the (1) clock (2) nerve centre (3) Both ‘1’ and ‘2’ (4) IC

Computer Architecture 17

61. The name of the location of a particular

piece of data is its (1) address (2) memory name (3) storage (4) data location

62. Which of the following is used to connect

the different external devices? (1) Address bus (2) Data bus (3) Control bus (4) External bus

63. Which is not an integral part of computer?

[SBI Clerk 2012] (1) CPU (2) Mouse (3) Monitor (4) UPS (5) None of these

64. A device that not only provides surge

protection, but also furnishes the computer with battery backup power during a power outage is [IBPS RRB PO Mains 2017] (1) Battery strip (2) UPS (3) Surge strip (4) USB (5) Memory

65. A temporary storage area, attached to the

CPU, for I/O operations is a (1) chip (2) buffer (3) register (4) core

66. To measure the speed of the processor, ..... is

used. (1) processing speed (2) clock speed (3) memory (4) unit

67. A uniform interval of CPU time allocated

for use in performing a task is known as (1) real time (2) seek time (3) down time (4) time slice

68. What is the full form of DMA?

(1) Direct Memory Access (2) Dynamic Memory Access (3) Direct Metho Access (4) Double Memory Access

69. The machine cycle includes

(1) fetch (2) decode (3) execute (4) store (e) None of these

70. When machine instructions are being executed

by a computer, the instruction phase followed by the execution phase is referred to as (1) program cycle (2) machine instruction (3) instruction cycle (4) task cycle

71. ....... is the process of carrying out commands.

(1) Fetching (2) Storing (3) Decoding (4) Executing

72. The processor must have two inputs

(1) instructions and data (2) information and data (3) input and output (4) CPU and instructions

73. ............. defines the parameters of the action

and depends on the operation. (1) Op-code (2) Operand (3) instructions (4) Data

74. Pipeline strategy is called implement

(1) instruction execution (2) instruction prefetch (3) instruction decoding (4) instruction manipulation

75. On the motherboard, the connection points

for chips are referred to as (1) slots (2) sockets (3) ports (4) lines

Computer Architecture 19

ANSWERS

1. (5) 2. (1) 3. (1) 4. (1) 5. (2) 6. (1) 7. (3) 8. (1) 9. (1) 10. (5)
2. (^) (2) 12. (^) (2) 13. (^) (2) 14. (^) (4) 15. (^) (3) 16. (^) (3) 17. (^) (1) 18. (^) (3) 19. (^) (3) 20. (^) (2)
3. (4) 22. (4) 23. (1) 24. (1) 25. (2) 26. (2) 27. (4) 28. (1) 29. (1) 30. (5)
4. (^) (1) 32. (^) (4) 33. (^) (3) 34. (^) (4) 35. (^) (1) 36. (^) (1) 37. (^) (3) 38. (^) (5) 39. (^) (4) 40. (^) (1)
5. (^) (2) 42. (^) (4) 43. (^) (1) 44. (^) (4) 45. (^) (2) 46. (^) (3) 47. (^) (1) 48. (^) (3) 49. (^) (2) 50. (^) (1)
6. (2) 52. (1) 53. (1) 54. (2) 55. (4) 56. (1) 57. (3) 58. (3) 59. (2) 60. (2)
7. (^) (1) 62. (^) (4) 63. (^) (4) 64. (^) (2) 65. (^) (2) 66. (^) (2) 67. (^) (4) 68. (^) (1) 69. (^) (5) 70. (^) (3)
8. (4) 72. (1) 73. (2) 74. (2) 75. (2)