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Q&A-KCSE Computer Studies Paper 1

State the areas where infra-red radio waves are used      KCSE 2018

  • TV remote control communication;
  • DVD remote communication
  • Communication between peripheral devices and the computer
  • Data link over a short distance using mobile phones Radio remote control
  • Remote locking/opening doors/ devices
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Explain the term website as used in the internet

  • A collection of related webpages under the same domain name
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Suggest two advantages of using robots, instead of humans, to build cars in the factory.

  • more efficient than a human
  • more accurate than a human
  • can lift larger and heavier equipment than a human
  • can replace humans working in a dangerous environment
  • reduces running costs, such as wages and overheads
  • can produce consistent results/output
  • can work 24 hours a day // do not need to take breaks.

 

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List two types of network software

  • Network operating systems
  • Protocols
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Confidential information about the students is to be stored on the computer system. Explain the measures that can be taken to ensure that such information remains confidential.

- Passwords
- Hierarchy
- Only allow some staff to access student files
- Only some machines able to access
- Physical location of these machines
- Physical lock on machines
- Encrypted data in files
- Firewall if connected to the Internet

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451/1

COMPUTER STUDIES

PAPER 1

THEORY

DECEMBER 2021

TIME: 2 HOURS

 

FORM TWO END OF TERM TWO 2O21 EXAM

451/1

COMPUTER STUDIES

PAPER 1

THEORY

TIME: 2½ HOURS

 

INSTRUCTIONS TO CANDIDATES:

  • Write your name and ADMISSION number in the spaces provided above.
  • Write the date of examination and sign in the spaces provided.
  • This paper consists of two sections.
  • Answer all the questions in section A.
  • Choose one topic to answer in section B
  • All answers must be written in the spaces provided in this question paper.
  1. SECTION A
  2.  Answer all questions in this section
  3. What is a computer?                                                                                                            1mks
  4. State three physical components that make up a computer                                                 3mks
  5. State the hardware technological differences between the second generation and third generation computers                                                                                                          2mks
  6. State and explain three characteristics of a computer                                                         3mks
  7. State the functions of the following special memories in a computer                                3mks
  8. Buffers
  9.  
  10. Registers
  11. Cache
  12.  
  13. Define the following as used in data representation in a computer                                  (5mks)
  14. Bit
  15.  
  16.  
  17. Byte
  18.  
  19.  
  20. Nibble
  21.  
  22.  
  23.  
  24. Word
  25.  
  26.  
  27.  
  28. Word-length
  29.  
  30.  
  31. State two reasons why a DVD is superior to a typical compact disk                               (2mks)
  32. State three advantages of flat panel monitors over cathode ray tube monitors                   3mks
  33. Explain the following terms as used in word processing                                                  3mks
  34. Section breaks
  35. Thesaurus
  36. Superscript
  37. State two advantages of  impact printers                                                                             2mks
  38. State the function of the following keys on the computer keyboard                                  3mks
  39. Enter key
  40. Insert key
  41. Delete key
  42. State the technology used by the following secondary devices to store data                      3mks
  43. Magnetic storage devices
  44. Solid state storage devices
  45. Optical storage devices
  46. State three reasons why an operating system is important in a computer                         3mks
  47. A typical computer’s main memory consists of both volatile and non-volatile memory.
  48. i)  Explain what is meant by the term volatile memory                                          (1mark)
  49. ii) What is normally stored in the non-volatile part of a computer’s main memory (1mark)
  50. Explain why having cache memory can improve the performance of the CPU         (2mks)
  51. What is a computer system?                                                                                           (1mk
  52. Give two differences between a solid state drive (SSD) and a hard disk drive (HDD)   2mks
  53. State three categories of software classified according User license agreement              (3mks)
  54. State two disadvantages of Random Access Memory                                                       (1mk)
  55.  
  56.  
  57. a) Explain the functions performed by the following components of a processor   (2 marks)
  58. Control unit
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What is a web browser?

  • A software which can display a webpage on a user's computer screen
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State the advantages and disadvantages of the command-line interface

Advantages

  • It is quicker to type commands
  • Little memory needed
  • Little processing power needed

Disadvantages

  • Commands have to be typed precisely
  • There is a large number of commands to be learnt
  • It is not user friendly
  • The user has to remember commands
  • Users cannot transfer data between applications
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What is repetitive strain injury?

  • the pain felt in muscles, nerves and tendons caused by repetitive movement and overuse.
  • Injury as a result of repetitive use of parts of the body while performing work
  • Strains and injuries due to prolonged typing and use of the mouse
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Explain how virtual memory can compensate for the limited  RAM capacity in a computer.

  • VM is used when RAM is full  i.e part of the secondary storage used as (temporary) RAM/VM
  • Data from RAM is moved to the secondary storage/VM (to make space in RAM)
  • RAM can then be filled with new data
  • When data in VM is needed it is moved back to RAM
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Describe each of the following types of a program errors, giving an example in each case.

(i) Syntax error.
(ii) Logic error.
(iii) Arithmetic error/runtime error

(i) Incorrect use of language, e.g. PLINT instead of PRINT
(ii) A mistake in the structure of the solution, e.g. a jump goes to the wrong line
(iii) Inappropriate arithmetic is used, e.g. division by 0 is attempted

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Describe two health risks associated with the increased use of computers.

  • RSI in wrists or fingers from prolonged typing or repeated clicking of mouse button
  • headaches/eyestrain/dry eye from staring at a monitor for long periods of time/glare from monitor
  • back ache/strain from sitting in the  same position for a long time/using chair with no adjustment
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One facility of a Software Development Environment is to convert source code to machine code.  Name and briefly describe four other facilities commonly found in a Software Development Environment.

  • Editor: this allows a programmer to enter and edit source code
  • Automatic formatting:  Correctly indents code
  • Automatic colour coding:  Changes key words, literals and annotation to different colours
  • Linker: this is a program which allows previously compiled code, from software libraries, to be linked together
  • Loader: this is a program which loads previously compiled code into memory.
  • Debugger: this is a program which helps locate, identify and rectify errors in a program
  • Syntax error detection:  Highlighting syntax errors before code is translated
  • Trace: this is a facility which displays the order in which the lines of a program are executed, and possibly the values of variables as the program is being run
  • Break point: this is a facility which interrupts a program on a specific line of code, allowing the programmer to compare the values of variables against expected values.  The program code can then usually be executed one line at a time.  This is called single-stepping
  • Variable watch: this is a facility which displays the current value of any variable.  The value can be 'watched' as the program code is single-stepped to see the effects of the code on the variable.  Alternatively a variable watch may be set, which will interrupt the program flow if the watched variable reaches a specified value
  • Memory inspector: this is a facility which will display the contents of a section of memory
  • Error diagnostics: these are used when a program fails to compile or to run.  Error messages are displayed to help the programmer diagnose what has gone wrong
  • Emulator: will provide and emulator to run the code/app so no physical device required
  • Context sensitive menu:  SDE suggests available options
  • Statement completion:  SDE will complete a statement such as adding an ‘end if’ to an ‘if’ statement GUI creation:  Allows programmer to create a GUI by dragging and dropping controls (buttons, etc...) onto a form.
  • Publisher: facility to package up and deploy program as an easy to install package
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Distinguish between transcription and transposition types of errors and give an example of each  (4mks)

Transcription Errors: Transcription errors involve the incorrect entry of data due to mistakes made during the copying or typing process. These errors can occur when transferring information from one source to another.

Transposition Errors: Transposition errors specifically refer to errors where the order of characters or digits is accidentally reversed or swapped. This can happen during manual data entry or when processing information.

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A computer operates as a binary digital device. Explain why binary is used to represent computer data.

  • Binary can represent two states because computer circuits use transistors, which can either be on or off
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Your friend wishes to install a wireless network in his office. Explain to him the difference between guided and unguided media

  • Guided media uses cables to connect to computers whereas unguided media uses waves.
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Differentiate between Physical and logical topologies

  • Physical topology deals with the placement of nodes
  • Logical topology deals with the data flow  in the network
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Explain each of the following function of an operating system

Job scheduling/Process scheduling                                                                                              (2mks)

  • Operating systems allocate tasks/processes/jobs to the CPU using priority and FIFO principle

 Memory management                                                                                                                  (2mks)

  • OS allocates and de-allocates memory spaces to processes loaded into the RAM
  • Swaps processes between main memory and virtual memory created in the secondary storage
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Describe the principles of operation of  laser printers and describe how they are applied in real-life scenarios

  • A laser printer makes use of powdered ink and static electricity to print
  • Unlike inkjet printers which print line-by-line, laser printers print the whole page in one go

Steps

  • The data from the  file to be printed is sent to a printer driver
  • The printer driver checks that the data is in an understandable format
  • The printer driver checks if the printer is able to carry out the print job
  • The data is sent to the printer and is stored in a printer buffer
  • A printing drum in the printer is given a positve charge. A laser beam removes the positive charge in some areas. This leaves negatively charged areas which matches the characters/images to be printed
  •  
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What is entity integrity?

  • It ensures that each row has a unique and non-null primary key
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