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Q&A-KCSE Computer Studies Paper 1

Describe two features you would expect to see in the expert system’s interactive user interface.

– multiple choice/yes-no answers
– easy to understand interface e.g. use of icons/drop down menus etc.
– output shown as % probabilities of fault

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Convert the following:

(a) the binary number \(1111 1100_2\) to hexadecimal.

(b) the denary number \(138_{10}\) to hexadecimal.

(c) the hexadecimal number \(5D_{16}\) to denary.


(a) \(F C_{16}\)

(b) \(8 A_{16}\)

(c) \(93_{10}\)

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Explain, using examples where appropriate, the meaning of these computer terms

(a) byte ..................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(b) compiler ............................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(c) handshaking .....................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(d) technical documentation ..................................................................................................
..........................................................................................................................................
......................................................................................................................................[2mks]
(e) simulation .........................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2

(a) byte

  • fixed number of bits, 8 bits
  • represents a character


(b) compiler  program

  • converts/changes/translates high-level language into machine code/machine language/low-level language/object code
  • changes each high-level language instruction into machine code instructions
  • produces an independent program capable of being executed by itself
  • all (syntax errors) listed
  • converts the whole program before execution/in one go
  • converts source code to object code

(c) handshaking

  • exchanging of signals to establish communication between two devices/computers e.g. printer and computer, modem and computer

(d) technical documentation

  • documentation to ensure that the system can be maintained/updated/altered/developed/upgraded
  • trouble shooting/correcting errors/correcting faults
  • explanation of what the program does/how the system works
  • contains file structures
  • algorithms/flow charts/pseudo code
  • program listings
  • hierarchical chart

(e) simulation

  • studying the behavior of a system by using a model/represents real-life/mathematical representation
    e.g. flight simulator (or others), hazardous applications results can be predicted
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At which stage of the system development life cycle does the changeover to a new system take place?

  • Implementation
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State the characteristics of each of the following network topologies (KCSE COMPUTER STUDIES 2021 )

i) Mesh Topology  (2mks)

  • a host/node is connected to one or multiple hosts
  • a   host/node in point to point connection with every other host or a few hosts
  • hosts/nodes in mesh topology also work as relays for other hosts which do not have point-to-point links

(ii) Ring Topology (2mks)

  • each host/node connects exactly to two other hosts
  • data travels around the ring in one direction through all intermediate hosts
  • failure of any host results in the failure of the whole ring

State the characteristics of each of the following network topologies (KCSE COMPUTER STUDIES 2021 )

i) Mesh Topology  (2mks)

  • a host/node is connected to one or multiple hosts
  • a   host/node in point to point connection with every other host or a few hosts
  • hosts/nodes in mesh topology also work as relays for other hosts which do not have point-to-point links

(ii) Ring Topology (2mks)

  • each host/node connects exactly to two other hosts
  • data travels around the ring in one direction through all intermediate hosts
  • failure of any host results in the failure of the whole ring
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A web server has an internet protocol (IP) address. Give three characteristics of an IP address.

  • consists of values between 0–255 / 0–FFF
  • values are separated by full stops/colons
  • it is a unique address
  • can be static or dynamic
  • can be public or private
  • can be IPv4 / have four groups of digits
  • can be IPv6 / have eight groups of digits
  • in IPv6 :: can replace groups of zeros.
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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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Outline a factor that can influence the performance of a network.

  • The different factors that can influence the performance of a network include: bandwidth, network design, data collisions, and excess broadcast traffic.
  • The bandwidth can influence through the method of transmission and medium used
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Factors to consider when choosing DTP software. (4 marks)

  1. Availability in the market
  2. Initial and maintenance cost
  3. User friendliness
  4. Compatibility
  5. User needs

State two benefits of using robots

  • reduced labour costs/do not need paying
  • reduced cost of goods
  • improve speed of production/productivity
  • high degree of accuracy/precision/less errors
  • can operate where humans can not go
  • do not take breaks/holidays/get tired
  • work 24 hrs a day
  • reduce accidents at traffic lights
  • improve traffic flow
  • can work in dangerous conditions

802.3 is the standard for ethernet wired networks and 802.11x is the standard for ethernet
wireless networks.
Outline why standards such as these are important in the development of network devices and
software.

  • Standards specify a set of rules for hardware and/or software used in network communications. Because all manufacturers must adhere to the standards when manufacturing network hardware or software, it means that all devices should be able to communicate, regardless of manufacturer.
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State two benefits of using computerised traffic control systems.

  • Better/improved traffic flow control
  • reduces accidents
  • keeps delays to a minimum
  • reduces pollution
  • cars use less fuel

Describe one effect of not having primary keys in tables in a relational database

Without a primary key, a table in a database may have duplicate rows, making data not uniquely identifiable. This can lead to issues with data integrity and challenges in maintaining relationships between tables. Retrieving and updating specific records becomes problematic, and setting referential integrity constraints is impossible, potentially leading to loss of data.

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State the type of software that is needed for logging onto the Internet and finding websites selling goods and services.

  1. logging on
  2. finding websites

logging on

  •  dial-up/communications software/ISPsoftware

finding websites

  •  browser/search engine
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List Three file organisation methods in a computer

  • Sequential
  • Random
  • Serial
  • Indexed-sequential
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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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The Unicode character set is used to represent text that is typed into a computer.
(a) Describe what is meant by a character set.

(b) One disadvantage of using the Unicode character set, instead of the ASCII character set, is
that the text stored takes up more storage space.

  • All the characters and symbols that can be represented by a computer system.
  • Each character and symbol is assigned a unique value.

(b) One disadvantage of using the Unicode character set, instead of the ASCII character set, is

that the text stored takes up more storage space

  • Each character is encoded using more bits

 

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Describe the main characteristics that distinguish high-level programming languages from low-level languages.

  1. Low level languages do not resemble natural languages they are made up entirely of bit patterns
  2. Low level languages produce code that is executed faster as it is already in a format the CPU can execute / does not need to be translated.
  3. High level languages are easier to understand / learn as commands are more like English / identifiers can be meaningful .
  4. High level languages are easier to use leading to fewer errors.

State the symptoms of a computer virus

  • Unfamiliar graphics or quizzical messages appear on the screen
  • Programs taking longer than usual to load
  • Less memory allowance than usual
  • Unusual error messages occurring more frequently
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State two computer-based careers  that have arisen as a result of  computer-based data processing in a factory    (2 marks)

System analyst

Web designers

Network administrators

Database administrators

Programmers

Computer technicians

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