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Q&A-KCSE Computer Studies Paper 1

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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Give three features of a data protection act.

  • data shall only be used for the specific purpose for which it was collected
  • data shall be adequate/relevant/not excessive
  • data shall be accurate/up to date
  • data shall not be kept any longer than necessary
  • individuals have the right to see data about them (and have it changed if inaccurate)
  • sufficient means taken for security/integrity of data
  • data shall not be transferred to a country with lower protection laws
  • data users must be registered
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Explain why a developer, who is good at both low-level and high-level programming, would normally use high-level languages when writing programs.

  • High-level languages have built-in functions;
  • High-level languages have built-in libraries;
  • High-level languages have more support/help;
  • High-level languages have structures (such as selection and iteration);
  • High-level languages can be less machine-dependent/more portable;
  • It (usually) requires fewer lines of code to be written;
  • It is (usually) quicker to develop code in high-level languages;
  • It is easier to find mistakes in code;
  • The code is easier to maintain//understand;
  • It is easier to structure code in high-level languages;
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 State two components of the CPU

Any two from:

  • Registers
  • Clock
  • CU
  • ALU
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Define Data Security

  • Is the protection of programs and data in computers and communications systems against unauthorized modification, access or disclosure
  •  
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There are four change-over methods used in the implementation stage of the system development life cycle (SDLC): direct change-over, phased, parallel and pilot.

Direct Change-Over

  • A date is chosen for the shutdown of the old system, then at that time, the old system
    is turned off and the new system is implemented

Phased

  • Parts of the new system are implemented in stages or for a period of time, both the old and the new system are running together until all parts of the system are implemented.
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State any four applications of electronic spreadsheets

  • Financial accounting
  • Prediction and forecasting
  • Inventory keeping
  • Budgeting
  • Keeping records
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State the differences between a hub and a switch

 

  • switches can send and receive data simultaneously - they are full duplex
  • a hub is half duplex- only one host can communicate at a time.
  • a hub broadcast signals to all computers connected in a network while a switch directs data to its intended destination
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Describe a typical situation that requires the use of:

(i) a high-level language

(ii) a low-level language.


High level languages are used in situations when:

  1. Speed of execution is not a critical factor, such as in office applications.
  2. a programmer needs to use complex commands that perform complex tasks.
  3. A programmer wants to make use of standardised library / sub routines.

Low level languages are used in situations when:

  1. a program must execute quickly such as real time applications
  2. a programmer needs to write code that interacts directly with the hardware, such as device drivers
  3. a programmer needs to perform a specific command not available in a HL language.
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Explain one drawback to a user if the program is distributed as freeware

The user is not allowed to access the source code so, they cannot tailor the software to their needs and  they cannot fix any bugs in it

The software is still covered by copyright

The user must get the owner’s permission to do anything beyond using it

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What are the functions of the system clock in the CPU?

  • It dictates the speed at which data is transferred between these components and enables the sequential execution of instructions in the correct order.
  • generates a timing signal that is used to synchronize communication between CPU components and the rest  of the computer system
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Define patch as used in the operating system

Refers to a small piece of software designed to update, fix, or improve a specific part of the operating system or an application.

NB: Patches are typically released by the software's developer or the operating system vendor to address security vulnerabilities, software bugs, or to add new features or enhancements

State two functions of utility software

  • Repairing files
  • Compression
  • Defragmentation
  • Back up
  • Anti-virus / anti-spyware / anti-malware
  • Firewall
  • Managing application updates
  • Format disks/drives
  • System analysis tools
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Explain the following terms

(a) Disk mirroring

(b) Encryption

(c) Backup

(a) Disk mirroring- Data is written on two or more disks simultaneously.

(b) Encryption - Contents are scrambled so they cannot be understood without a decryption key

(c) Backup - A copy of the data is taken and stored in another location

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Give two examples of each of the following application packages       

a)Spreadsheets                                                                                                                               (2mks)

  • Microsoft Excel
  • Lotus 1-2-3
  • Google Sheets
  • OpenOffice Calc

                                           Any 2 @ 1mk

 

b) Word processors                                                                                                                          (2mks)

  • Microsoft Word
  • Wordpad
  • Corel WordPerfect
  • Lotus Word Pro

 

                                         Any 2 @ 1mk

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State the functions of the following:

  1. Hub
  2. Router
  3. Switch
  4. Bridge

Bridge: Joins together two networks that use the same base protocols.

Hub: Copies all packets of data to all devices on the network.

Router: Stores the addresses of computers on the network and transfers data between devices.

Switch : Analyses each data packet and sends it to the computer it was intended for.

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Give one application of each type of data transmission. Each application must be different

Parallel

  • sending data from a computer to a printer
  •  internal data transfer (buses)

Serial

  • connect a computer to a modem
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Xpat ICT has been tasked to construct a network for an organisation. Explain three factors that the company should consider when selecting the medium for the connectivity (KCSE 2021 Computer Studies Q19c)

  • Security
  • Installation cost
  • bandwidth the medium can support
  • Flexibility e.g wireless media
  • Distance
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Ahmed uses the Internet for some time and is puzzled by the terminology.
(a) Draw a line to match each description to the appropriate technical term.

  • a computer that responds to requests to provide information and services over the Internet - an Internet server
  • defines how messages are transmitted and formatted over the Internet-HTTP
  • software that enables users to access/view documents and other resources on the Internet - Browser     
  • numerical ID for each device on the Internet-IP address
  • unique ID for a network interface card  -MAC address
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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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