Computer Awareness Study Material – Computer Architecture

Computer Awareness Study Material – Computer Architecture

Computer architecture deals with the functional behavior of a computer system as viewed by a programmer. It can also be described as the logical structure of the system unit that housed electronic components. The computer architecture forms the backbone for building successful computer systems.

Components of Computer
A computer consists of following main components

1. Input/Output (I/O) Unit Central Processing Unit
2. Memory Unit

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

• It accepts the instructions and data from the user.
• It converts these instructions and data in computer in acceptable format.
• 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. video monitor, printer and plotter, etc.
The following functions are performed by an output unit

• It accepts the results produced by the computer which are in coded form and hence cannot be easily understood by us.
• It converts these coded results to human acceptable, form.
• It supplies the converted results to the user.

Central Processing Unit (CPU)
It consists of 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

• The CPU transfers instructions and input data from main memory to registers, i.e. internal memory.
• The CPU executes the instructions in the stored sequence.
• 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 (1C) 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 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

• Logical operations (AND, NOT, OR, XOR)
• Arithmetic operations (addition, subtraction, multiplication and division).
• Bit-shifting operations (shifting or rotating a word by a specified number of bit to the left or right with or without sign extension).
• Comparison operations (=, <, <=,>,> =)

Registers
These are special purpose and high speed temporary memory units. Registers are not referenced by their address, but are directly accessed and manipulated by the CPU during execution. Registers store data, instructions, address and intermediate results of processing.
The number and size of registers vary from processor to processor.

Control Unit
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.

Microprocessor
The microprocessor 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.

• Intel 4004 was the first microprocessor made by Intel in 1971 by scientist Ted Hoff and engineer Frederico Faggin.
• Some of the popular microprocessors are Intel core i7, Intel, 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.
The needed instruction for processing and any kind of intermediate results are also stored in primary memory. Together with these, the final output is also stored in primary memory before transferring it to the output unit. Another kind of memory is referred 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. The biggest piece of silicon housed in the system unit of a computer is motherboard.
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.

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.
In other wouds, 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

• The command to access the memory or the I/O device is carried by the control bus.
• The address of I/O device or memory is carried by the address bus. The data to be transferred is carried by the data bus.

2. External Bus The external bus 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.

Instruction Cycle
The instruction cycle represents the sequence of events that takes place as an instruction is read from memory and executed.

A simple instruction cycle consists of the following steps

1. Fetching the instruction from the memory.
2. Decoding the instruction for operation.
3. Executing the instruction.
4. Storing in memory.

In above steps, step 1 and 2 instructions are same and known as fetch cycle and step 3 and 4 instructions are different and known as execute cycle.

Instructions Format
Computer understands instructions only in terms of 0’s and l’s, which is called the machine language. A computer program is a set of instructions that describe the steps to be performed for carrying out a computational task. The processor must have two inputs; instructions and data.
The instructions tell the processor what actions are needed to be performed on the data. An instruction is further divided into two parts; operation (op-code) and operand. The op-code represents action that the processor must execute and the operand defines the parameters of the action and depends on the operation.
Machine cycle is defined by the time, that takes to fetch two operands from registers and performs the ALU operation and stores the result in a register.
Pipelining improves execution speed by putting the execution steps of several instructions into parallel.
Sockets are the connecting points of chip on the motherboard.
Load instruction is used for loading data into CPU accumulator register from memory.

QUESTION BANK

1. On the motherboard, the connection points for chips are referred to as

1. slots
2. sockets
3. ports
4. lines
5. None of these

2. Internal memory in a CPU is nothing but

1. a set of registers
2. a set of ALU
3. microprocessor
4. bus
5. None of these

3. The word ‘computer’ usually refers to the central processing unit plus

1. external memory
2. internal memory
3. input devices
4. output devices
5. None of these

4. Which of the following is a part of central processing unit?

1. Printer
2. Keyboard
3. Mouse
4. Arithmetic Logic Unit
5. All of the above

5. Control unit of a digital computer is often called the

1. clock
2. nerve centre
3. Both ‘1’ and ‘2’
4. IC
5. None of the above

6. 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
5. None of the above

7. A group of bits that tells the computer to perform a specific operation is known as

1. instruction code
2. micro-operation
3. accumulator
4. register
5. None of the above

8. ……….. are special purpose and high speed temporary memory units.

1. registers
2. ALU
3. CU
4. CPU
5. None of these

9. Memory unit that communicates directly with the CPU is called the

1. main memory
2. secondary memory
3. auxiliary memory
4. register
5. None of the above

10. Where does computer add and compare data?

1. Hard disk
2. Floppy disk
3. CPU chip
4. Memory chip
5. None of these

11. Pipeline strategy is called implement

1. instruction execution
2. instruction prefetch
3. instruction decoding
4. instruction manipulation
5. None of the above

12. 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
5. machine cycle

13. Which computer memory is used for storing programs and data currently being processed by the CPU?

1. Mass memory
2. Internal memory
3. Non-volatile memory
4. PROM
5. None of the above

14. Following are names of motherboard except

1. system board
2. main board
3. planar board
4. logic board
5. computer board

15. The central processing unit is an example of

1. peripheral
2. output unit
3. software
4. program
5. hardware

16. Which of the following include as type of input?

1. data
2. programs
3. commands
4. user response
5. All of these

17. …….. selects, interprets and executes instructions in a CPU.

1. Control unit
2. ALU
3. Memory
4. Storage
5. Input unit

18. CPU retrieves its data and instructions from

1. secondary memory
2. auxiliary memory
3. main memory
4. All of these
5. None of these

19. …….. the raw facts from which……….. is derived.

1. Data, information
2. Data, output
3. Input, information
4. Output, input
5. Information, message

20. The address of I/O device or memory is carried by the

1. data bus
2. expansion bus
3. address bus
4. system bus
5. None of these

21. ………… is the process of carrying out commands.

1. Fetching
2. Storing
3. Decoding
4. Executing
5. None of these

22. Pick the one that is used for logical operations or comparisons such as less than, equal to or greater than.

1. ALU
2. CU
3. Input unit
4. MU
5. None of these

23. The………. is responsible for decision­ making mechanisms.

1. CPU
2. MU
3. ALU
4. CU
5. None of these

24. Which of the following components is the most essential for the computer system to work?

1. Input system
2. Output system
3. Storage system
4. Monitor
5. CPU

25. A(n)………. device is any device that provides information, which is sent to the CPU.

1. input
2. output
3. CPU
4. memory
5. processing

26. Which of the following controls the machine cycle?

1. Control unit
2. Memory unit
3. Logic unit
4. Arithmetic unit
5. None of these

27. Which of the following executes the computer commands?

1. Arithmetic unit
2. Logic unit
3. Both ‘1’ and ‘2’
4. Control unit
5. None of these

28. The machine cycle includes

1. fetch
2. decode
3. execute
4. store
5. All of these

29. Which instruction is used for loading data into CPU accumulator register from memory?

1. Load
2. Storage
3. Machine
4. Access
5. Cycle

30. Computations and logical operations are performed by the

1. RAM
2. ALU
3. register
4. control unit
5. None of these

31. Who invent the first microprocessor?

1. Vint cerf
2. Terence Percival
3. Heorku
4. Ted Hoff
5. None of the above

32. The system unit

1. coordinates input and output devices
2. is the container that houses electronic components
3. is a combination of hardware and software
4. controls and manipulates data
5. does the arithmetic operations

33. To measure the speed of the processor,…… is used.

1. processing speed
2. clock speed
3. memory
4. unit
5. speed measurement

34. The CPU is made up of two smaller components

1. ALU and CU
2. ALU and RAM
3. RAM and ROM
4. RAM and CU
5. None of these

35. The term……. designates equipment that might be added to a computer system to enhance its functionality.

1. digital device
2. system add-on
3. disk pack
4. peripheral device
5. None of these

36. It is also called the brain of the computer, is responsible for processing data.

1. Motherboard
2. Memory
3. RAM
4. Central Processing Unit (CPU)
5. None of the above

37. Which circuit board is used in all electronic systems such as computer, calculators, digital system?

1. Architecture
2. Printer
3. Value
4. Register
5. None of these

38. Another name for a logic chip is

1. PROM
2. memory
3. microprocessor
4. ROM
5. RAM

39. Microprocessors can be used to make

1. computer
2. digital system
3. calculators
4. All of these
5. None of these

40. CPU stands for 

1. Computer Processing Unit
2. Central Processing Unit
3. Computer Protection Unit
4. Central Processing Upload
5. None of the above

41. The communication line between CPU, memory and peripherals is called a

1. bus
2. line
3. media
4. All of these
5. None of these

42. The control unit controls other units by generating                           

1. control signal
2. timing signal
3. transfer signal
4. command signal
5. None of these

43. The main circuit board of the system unit is

1. computer program
2. control unit
3. motherboard
4. RAM
5. None of these

44. This component is required to process data into information and consists of integrated circuits.    

1. Hard disk
2. RAM
3. CPU
4. ROM
5. None of these

45. Which is not an integral part of computer?

1. CPU
2. Mouse
3. Monitor
4. UPS
5. None of these

46. The load instruction is mostly used to designate a transfer from memory to a processor register known as

1. accumulator
2. instruction register
3. program counter
4. memory address register
5. None of the above

47. The basic goal of computer process is to convert the data into                

1. files
2. tables
3. information
4. graphs
5. None of these

48. Arithmetic logic unit and control unit sections have special purpose locations called

1. registers
2. RAM
3. BIOS
4. I/O
5. ROM

49. Which part of the computer is used for calculating and comparing?

1. ALU
2. Control unit
3. Disk unit
4. Modem
5. None of these

50. The CPU comprises of control, memory and ….. units.             

1. microprocessor
2. arithmetic/logic
3. output
4. ROM
5. input

51. ‘C’ in CPU denotes

1. Common
2. Central
3. Convenient
4. Computer
5. Circuitry

52. A microprocessor is the brain of the computer and is also called a

1. microchip [RBI Grade B 2014]
2. macrochip
3. macroprocessor
4. calculator
5. software

53. If a processor has a word size of 32 bits compared to a processor with a word size of 16 bits, it can                at a time.

1. twice as much .
2. half as much
3. thrice as much
4. the same amount
5. a forth as much

54. Which of the following company developed the microprocessor?

1. Intel
2. IBM
3. Microsoft
4. Apple
5. Google

55. What does ALU in computing denote?

1. Application and Logic Unit
2. Algorithm Logic Unit
3. Arithmetic Layered Unit
4. Arithmetic Legal Unit
5. Arithmetic Logic Unit

56. The main circuit board in the computer that connects the parts of the computer is the

1. motherboard
2. father board
3. match board
4. hard drive
5. special board

57. Which of the following manages computer resources? 

1. ALU
2. BUS
3. Control unit
4. I/O unit
5. Secondary memory

58. What is the responsibility of the logical unit in the CPU of a computer? 

1. To produce result
2. To compare numbers
3. To control flow of information
4. To do Maths work
5. None of these

59. Which of the following is not a function of the control unit?       

1. Read instructions
2. Interpret instructions
3. Execute instructions
4. Direct operations
5. Provide control signals

60. ………… is when the more power-hungry components, such as the monitor and the hard drive, are put in idle. 

1. Hibernation
2. Power down
3. Standby mode
4. The shutdown procedure
5. None of these

61. The portion of the CPU that coordinates the activities of all the other computer components is the   

1. motherboard
2. coordination board
3. control unit
4. arithmetic logic unit
5. None of these

62. Which among the following is an important circuitry in a computer system that directs the operation of the processor

1. Memory
2. Address Bus
3. Accumulator
4. ALU
5. Control unit

63. What is the brain of the computer called?

1. Keyboard
2. Mouse
3. CPU
4. Printer

64. 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

ANSWERS