• Access Controls: Authentication of users in order to access files
• Performing regular patches of updates
• creating secure accounts with required privileges
• scrutinizes all incoming and outgoing packets of data through a firewall
• encryption of data, during transmission
• Log files to detect any breach

• It is a feature used to prevent unwanted changes to be made on the data contained in a sheet by limiting the ability to make changes

• camera film speed, position (end of film), distance, light
• washing machine amount of water, speed of wash/temperature/time
• fridge temperature, display panel
• air conditioning temperature, timing, display pane

(a)

• Hardware required by each computer to connect to a network is a Network Interface Card / NIC / network adapter

(b)

• Computer A adds computer D’s address to packet
• Computer A sends packet to switch
• Switch looks at address on packet  Switch compares to stored list of addresses on network
• Switch forwards packet to computer D’s address

Describe how the computer on board the aeroplane uses GPS to find its exact location

– satellites transmit signals to onboard computers
– computers receive/interpret these signals
– system depends on very accurate timing/use of atomic clocks
– each satellite transmits data indicating location and time
– computer in aeroplane calculates location based on at least three satellites
– at least 24 satellites in operation at any one time
– position accurate to within one metre
– can also calculate altitude of aeroplane
– ref to “triangulation”:

Give two benefits of using GPS in this application

– safer as the known location is exact/more accurate
– reduces the possibility of pilot error
– allows accurate estimation of arrival time
– display and guide the pilot to the nearest airport in case of emergency

SECTION A (40 MKS)

Answer all the questions in this section.

1. a) What is disk formatting?                                                        (1mk)

b) Indicate whether the following devices are used for input or output  (2mks)

i) Plotter

ii)Light pen

iii)Mouse

iv)Visual display unit

2.a)Explain why the following and give one reason why they are not allowed in a computer laboratory. (2mks)

b) For each of the following give one reason why they are not allowed in a computer laboratory.  (2mks)

i) Smoking

ii)Eating foods

3.Distinguish between Real, integer and Character data types as used in programming (3 mks)

4.The cells k3 to K10 of a worksheet contain remarks on student’s performance such as very good, good, fair and fail depending on the average mark.  Write a formula that can be used to count all students who have the remark “very good”      (3mks)

5.a) State the purpose of registers in a computer system               (1mk)

b)Name two multiprogramming operating systems                   (2 mks)

6.a) A series file comprises of records placed in positions 1 to 10.  State the position of the end of file marker.      (1mk)

  b)State the purpose of each of the following: (2mks)

 i)File server software

ii)Communication software

7.a) Name the control structure depicted by the flowchart below.                   (1 mk)

b)Explain the following terms as used in program implementation.      (2mks)

 i)Parallel running

 ii)Direct change over

8. Consider the linear arrays:

 i) AAA (5:50)

 ii)BBB (-5:10)

 iii)CC (18)

Find the number of elements in each array (3mks)

9.Define the term artificial intelligence  (2 mks)

10.Name two types of relationships that can be applied in database design  (2mks)

11.Explain binary Coded Decimal code of data representation (1 mk)

 a)Indenting

 b)Alignment

 c)Word wrap

12.Outline two ways in which a computer can be used in hotels               (2 Marks)

13.a)Explain Binary Coded Decimal code of data representation (1marks)

 b)Write the number 4110 in BCD notation (1 mk)

14.Arrange the following data units in ascending order of size.

   BYTE, FILE, BIT, NIBBlE     (2mks)

15.State two health issues that may result from prolonged use of computers     (2 mks)

SECTION B (60 MARKS)

16. a) State the stage of program development in which  (4 mk)

i) A flowchart would be drawn

 ii)The programmer would check whether the program does as required

 iii)The user guide would be written

iv)The requirements specifications would be written.

b)State the output of the following flow chart segment                  (1mk)

c) i)Draw a flowchart to compute the combined resistance ® of two resistors R1 and R2 in parallel using the formula;

                      (5mks)

ii)Write a program using Pascal or C languages for the flowchart in C (i) above. (5 ½ mks)

17. a)List three paragraph formatting activities in word processing  (3mks)

 b)Differentiate between bolding and highlighting text (2mks)

c) The following information shows the income and expenditure for “bebayote “ matatu for five days.  The income from Monday to Friday was Kshs. 4,000, 9,000, 10, 000, 15,000 and 12,000 respectively while the expenditure for the same period was Kshs.  2,000, 3,000, 7,000, 5,000 and 6,000 respectively

i)Draw a spreadsheet that would contain the information.  Indicate the rows as 1, 2, 3 …. And the columns as a, B, C    (4mks)

ii)State the expression that would be used to obtain:

 I Monday’s profit  (2mks)

 II Total income (2mks)

III)Highest expenditure (2mks)

18.a) Subtract 0112  from 10012 (1mk)

 b)Using two’s compliment, subtract 7 from 4 and give the answer in decimal notation (4mks)

c) Convert

i) 91B16  to octal    (3mks)

ii) 3768   to hexadecimal   (3mks)

iii) 9.62510 to binary  (4 mks)

19.a) Explain what the following DOS commands will do when executed.

    i)  A: \copy *.* B:    (2 mks)

   ii)   C: \> ERASE*. DOC   (2mks)

  iii)   b: \> Md EXAMS  (2mks)

 b)  i)  With the aid of a diagram, explain hierarchical (tree) network topology   (3mks)

  ii)List two advantages and two disadvantage of hierarchical network topology.  (4 mks)

   Advantages:-

   Disadvantages:

20. a)Name and explain the function of the keyboard keys represented by the following symbols.

  b) Simulation is one of the application areas of computers        

  i) What is meant by the term simulation      (1mk)

  ii)Name two application areas of simulation   (2 mks)

 iii) State three advantages of computer based simulation (3 mks)

 c) Explain three ways in which computers have impacted education (3mks)

CLI

• Commands have to be typed in full with no mistakes
• Requires memorization of commands
• Uses less memory

GUI

• Due to graphics, GUI uses a lot of memory
• GUI is more user friendly
• Cannot operate properly if memory is low

Comparison

• Both carry out file management
• Both are operating systems
• Both control software and hardware

specify output requirements
design documents/screen displays
data for input/storage
form design
storage devices
file structures/access/design
data security/back up files
systems flowchart etc.
implementation i.e. pilot/intermediate/parallel running
testing strategy
training
hardware/software
programming/algorithms
validation
user manual
technical documentation
entering data into system

The Fetch – Execute cycle is a sequence of actions, performed by the processor as it fetches
a program instruction from its memory, determines what the instruction wants to do and
carries out those actions. The stages of the cycle are provided below.

• Fetch the instruction – the processor fetches the instruction from a memory address stored in a program counter and transfers the instruction, via a data bus, to an instruction register. At the end of the fetch operation, the counter points to the next instruction that will be read in the next cycle.
• Decode the instruction – the processor decodes the instruction stored in the instruction register, including getting any operands required to complete the instruction.
• Execute the instruction – the decoded instruction is executed.
• Store the result – the result generated by the execute phase is stored in the main memory, and/or sent to an output device. The program counter is updated with feedback from the arithmetic logic unit (ALU), to a different address from which the next instruction will be fetched.

• The users may not have gained enough confidence to run the new system
• It may be very inconveniencing in case the new system fails or faces problems
• The weaknesses of the old system may not be corrected or may still be transferred to the new system

• 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

Parallel

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

Serial

• connect a computer to a modem

State four threats that compromise data integrity

• Human error
• natural disaster
• data transmission errors
• software bugs

How threats to data integrity can be minimised:

• Backup data preferably on an external storage media
• control access to data by enforcing security measures
• design user interfaces that minimise chances of invalid data entry
• using error detection and correction software when transmitting data over the network
• using devices that directly capture data from the source such as bar code readers, digtal cameras, and optical character readers

Branch of computer science based on enabling computers to
behave like humans/mimic aspects of human intelligence
• AI is implemented in software.
• Combines psychology, biology, linguistics, mathematics, neuroscience,
and philosophy (ethics)
• AI is not the same as the general intelligence of human beings

Uses – Any of the following:
• Game playing (chess, quiz, video games)
• Analytics (analyse buying patterns, predicting behaviours, predictive
text, financial markets)
• Image processing (recognising objects/patterns)
• Logistics (scheduling, order fulfilment)
• Control systems (cars, manufacturing, weapons, navigation)
• Expert systems (medical, mechanical, electrical diagnosis)
• Neural networks (simulating neuron behaviours as in brains)
• Natural languages processing (chatterbots, chatbots, speech
recognition)
• Robotics (dangerous situations, help aged or disabled)

Ethical issues – Any of the following:
• Take the work of humans, thereby affecting employment rates
• Is a computer to be trusted to make decisions (life-death)?

• If a computer discovers something that humans can’t prove, should it be
accepted as truth?
• Do AI machines have rights?
• Will people be comfortable interacting with machines that are
considered intelligent?

• (Cache) Stores regularly accessed instructions/data
• Reduces the need to access instructions/data from the main memory
•  Makes up for the difference in speed of the CPU and main memory

Program counter // PC
• Stores the address of the next instruction to be fetched
Memory address register // MAR
• Stores the address where data/instruction is to be read from or saved to
Memory data register // MDR
• Stores data that is about to be written to memory // Stores data that has just been read from memory
Current instruction register // CIR
• Stores the instruction that is currently being decoded/executed

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

• Application software refers to software that is designed to help the computer user to accomplish specific tasks
• Examples of application software include; Internet browsers, word processors, spreadsheets, databases etc
• System software is software that performs tasks needed to operate the hardware and provide services to other software
• Examples Operating Systems, Networking software, utility programs(encryption, backup, disk defragmentation software, ...)

• Any new or changed files since the last backup

• Portable
• Light
• Faster access speed
• No moving parts
• Efficient power consumption
• Durable
• Small physical size
• Large storage capacity