COMPUTER STUDIES MARKING SCHEME

PAPER 1THEORYJULY / AUGUST, 2019

TIME 2 ½ HOUR

CHANIA ZONEJOINT INTER-SCHOOLS EVALUATION TEST

(CZJISET)1. Name the parts labeled in the diagram below of a page layout properties [3 marks]

i ii iii

i- Hyper link to insert a link to a web pageii- Bookmark to make a link to a given position in the pageIii-cross reference making a page number containing an item where the page can be selected automatically

2. Explain briefly how an uninterruptible power supply (UPS) may help to protect acomputer system and its data. [1 mark]An uninterruptible power supply (UPS) contains surge protection circuitsand one or more batteries that can provide power during a temporary orpermanent loss of power.

3. How is data verification different from data validation? [1 mark]Data verification is the checking for mistakes when data is copied from one place to another ,Validation ensure that data is reasonable, acceptable e.g. a person’s height being 10 metersGive one example of data validation technique [1 mark](i.e., transcription errors(transposition errors, substitution errors)Give one example of data verification technique [1 mark]Type checks, Range checks,size checks

4. What kind of program is normally contained in a ROM chip and Explain briefly the mainpurpose of such a program. [2 marks]

ROM contains the basic input/output sytem (BIOS), which is a sequence of

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instructions the computer follow to load the operating system and other files when the computer is first turned on.

5. Distinguish between system software and application software. [2 mark]System: -software that manage computer resources.

Application: - software that user uses to solve his/her problems, carry out user task

6. Give the similarities between optical mark readers and optical character readers. [2 marks]

Data capture devices

Use light to capture data/read documents (i.e. optical)

Input devices

(Any 2 @ 1 mark each)

7. In word processing, distinguish between text insertion and overtyping. [2 marks]Text insertion: -introduction of a new text (character) between existing text (characters)Overtyping: - introduction of new text / character by placing the new text / character in place of the old text. (i.e. replacement of old text with new text)

(Difference must be showed. marked as a whole)

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

(i) interrupt [2 Marks]

temporary break in (CPU normal) execution of instructionsto allow it to handle request from a device/peripheral/programcaused by external eventcan be hardware or software generated

e.g. printer out of paper, <BREAK> key pressed, error in program

(ii) buffer [2 Marks]

Temporary memory/storage (area)to compensate for speed difference of device and CPU

used in transfer of data between computer and componentsallows CPU to carry out other functions while printing (etc.)

e.g. printer buffer, keyboard buffer [2]

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9. Explain the following spreadsheet concepts:

(i) Automatic Recalculation. [1 mark]Automatic change of a value in a cell as a result of changes in other cells values associated to the by formulae.

(ii)What if analysis [1 mark]Manipulation of values in a spreadsheet so as to see the likely outcome of such action. Used in decision-making. Simulation of situations using spreadsheets.

10. Explain briefly why the advancement of computer technology has caused environmental hazards. [2 marks]Computer technology advances so rapidly that the life of computer is just a few years.The increasing turnover rate of computer equipment results in a rapidly growing waste stream that is hazardous to our environment.

11. (i)What is telecommuting? [1 mark]Telecommuting is a work arrangement in which employees work away from acompany’s standard workplace, and often communicate with the office using some type of communications technology.(ii)State four benefits of telecommuting. [2 marks]Reduce time and expense spent traveling to the office.Eliminate travel during unsafe weather conditions.Allow a more flexible work schedule.Require less office space, furniture, and so on.(ii)How is e-commerce different from e-business? [1 mark]E-commerce is a term to describe purchasing goods or services online. E-business is an umbrella term to describe doing business on the Internet, which has also included e-commerce.

12. (i)What is a coprocessor? [1 mark]A coprocessor is a special processor chip or circuit board that assists the processor in performing specific tasks.(ii)How does parallel processing work? [1 mark]Parallel processing divides up a problem so that multiple processors work on their assigned portion of the problem at the same time.(iii)What is pipelining? [1 mark]With pipelining, the CPU begins executing a second instruction before it completes thefirst instruction, which results in faster processing.

13. (i)What is a driver program? [1 mark]A driver program interprets the device to the operating system. An internal interface between the hardware and the operating system(ii). Give one example of hardware device that may serve more than one purpose (e.g., input

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and output). [2 marks]A floppy drive or magnetic drive is an input device when data is retrieved from the floppy disk into the computer, and it is an output device when data is written onto a floppy disk.

14. (i)How is a patent different from a trademark? [2 marks]A patent is an exclusive right granted for an invention.A trademark is a formally registered symbol or sign identifying certain goods orservices as those produced or provided by a specific person or enterprise.(ii)What is the difference between unauthorized access and unauthorized use? [2 marks]Unauthorized access is the use of a computer or network without permission.Unauthorized use is the use of a computer or its data for unapproved or possibly illegalactivities.

15. (i)What is a workstation? [1/2 mark]A workstation is a networked computer used to access the contents of the central computer (i.e., the server).(ii)What is a server? [1/2 mark]A server is the central computer in a network used to manage network resources.

SECTION BAnswer question 16 (compulsory) and any other three questions from this section

16. (a) Explain the three control structures in programming [3 Marks]

Selection – A course of action is chosen depending on the outcome of a particular event or decision.Repetition – An action or set of actions is repeated over and over again until either the required number of repetitions is reached or a condition is met which halts the repetition

Sequence-the statements following each other in a given order

(b)State and describe three types of error can occur in programming [3 Marks]

(i) Syntax errors- are mistakes in the programming language’s keywords or control structures. They show up when the program is being entered.

(ii) Runtime errors- show up when the program is run. The program begins to run but the computer cannot carry out one of the instructions and crashes.

(iii) Logical errors-occur when the program runs but produces wrong results. They show up when the program is being tested.

(c)(i) State two differences between a compiler and an interpreter [2 marks]

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A complier translates all high-level language statements at the same time while aninterpreter translates only one high-level language statement at a time.

A complier translates the complete program first before allowing it to run while aninterpreter translates and runs the program at the same time.

(ii)Give one advantage of compliers over interpreters [1 mark]After compilation, the object program can be saved for future use without compiling the source program again.(iii)Give one advantage of interpreters over compliers [1 mark]Since the program statements are translated and executed one by one, it is easier forthe programmer to know which statement is incorrect.(d) Draw the corresponding flowchart for the pseudocodes below. [4 marks]

Assign 0 to A,Repeat adding 1 to A,Until A is greater than or equal to 5,Print A.

17. (a) How is peer-to-peer network different from client/server network, considering howprograms, data and information are stored? [2 marks]For peer-to-peer network, each computer stores data and information on its ownstorage devices. Network operating system and application software must also beinstalled on each computer.For client/server network, the server provides a centralized storage for programs, data,and information

(b)(i) Give three advantages of optical fibers over twisted-pair wires and coaxial cables.[3 marks]

Faster transmission speed due to greater bandwidths. Data can be transmitted digitally. Not susceptible to electrical interference.

(ii) Suggest two disadvantages of optical fibers. [1 mark] More expensive and difficult to install. More fragile than other wire-based communications channels.

Each ½ mark (c) (i)Compare asynchronous and synchronous transmission. [1 mark]

(ii) Give one disadvantage of the c(i) above [1 mark]

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Each ½ mark

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(d) (i)Compare the following Ring ,star and bus network topologies. [1 ½ marks]

any 1 of each 1 /2 mk

(ii)Give one disadvantage of each [1 ½ marks]

Bus Ring Star

any 1 of each 1 /2 mk

(iii)Draw a diagram t represent the ring ,star and bus topologies [1 ½ marks]

(e) (i) Explain the term upload [1/2 mark] Storing a file into a web server (ii)If a 56K modem is operating at full speed, how long does it take to download a 1-MBfile?

[2 marks]

1 MB ÷ 56 Kbps = (220 × 8) bits ÷ (56 × 103) bps7

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= 149.8 s18. (a).Describe the role of the systems analyst. [2 marks]

A systems analyst observes, clarifies and models an existing system; with a view to improving it through computerization (b).Describe 2 techniques used by the systems analyst in requirements specification.[2 marks]

Interviewing those involved with current system; Observing how the current system operates; Identifying the data requirements and the data flow of the current system.(b).In the software development process, what happens at the analysis stage? [1 Mark]

At the analysis stage, the system analyst and the person requesting the software get together to clarify the problem and identify in detail what the solution must provide.

(c)Describe fully what is meant by the term top-down design? [3 Marks]

The problem is set out at the top level as a series of large steps. Each step is then broken down further until at the bottom level, each small step describes a

single task. Each task can be easily coded into the required programming language.

(d)The process of developing such software is an iterative process. What does iterative mean?[1 Mark]

Iteration means that some of the steps in the development process may have to be repeated. At each stage, new details about the problem may emerge, the client may request a slight change, a technological innovation may have to be incorporated, or a error may be detected. The systems analyst will go back through all the previous stages to check that they are still valid and correct.)

(e)(i)What are CASE tools? [1 Mark] Software tools for each stage of the software development process.

(ii)What is the purpose of CASE tools? [1 Mark]They speed up the SD process by automating some of the activities

(iii)What does CASE stand for? [1 Mark] Computer Aided Software Engineering

(f)Identify ant two activities within the design stage of the software development process. [3 Marks] Design of the HCI(Human computer interface) Design of the program structure Design of the detailed logic of the program components.

19. (a).Describe four functions of a single user operating system. [4 Marks]

Memory management – ensuring one program does not overwrite another and that there is enough space to load a file, etc;

File management – the organisation of data and program files on backing storage; Input – output – to manage I/O and to ensure differences in system devices are compensated

for Process management – order of processing of tasks in CPU.

(b)Explain the need for an operating system to have a command language interpreter. [1 Mark]8

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The command language interpreter converts the commands entered by the user to binary , interprets them and passes them on to the appropriate sub-system within the OS for action .

(c)Give 4 examples of the many processes which can be initiated by a user and which are then carried out by the operating system. [4 Marks]

Load file from backing store Print file Save data file to backing store Execute a program file after loading to RAM

(d)What happens if a command entered by the user is not recognized by the operating system?[1 Mark]

If the user enters an invalid command or enters a command with a syntax error then the CLI reports that error to the user, usually through a dialogue box.

(e)Describe an advantage and a disadvantage to storing the operating system in RAM rather than in ROM? [2 Marks] Advantage: computer manufacturer can issue operating system updates very easily so that

computer users do not need to be always buying new systems; Disadvantage: OS may be overwritten or corrupted by mistake(g)Describe three features that a networkoperatingsystem must have that a single user operating system does not need. [3 Marks]

A network OS must ensure data integrity in data transfer across the network; A network OS must allow multi-user access; A network OS must be able to set access rights for different users20. (a)Explain two reasons why computers use the binary system? [2 Marks]

Binary arithmetic is simple to implement because there are only 2 digits and 4 arithmetic rules.

Electronic circuitry has only two voltage levels, pulse or no pulse, so it is easy to distinguish between 0 and 1.

(b)What is meant by the term word in the phrase 16-bit word computer? [1 Mark]A word is the amount of data that is handled by the processor in a single operation, in this case, 16 bits or 2 bytes.

(c)What is the decimal value of the largest integer that can be represented by a byte in a computer which deals only with positive numbers? [1 Mark] 255 or (2^8 – 1). (Remember that one of the 256 bit patterns is for zero.)

(d)What does the acronym ASCII stand for and what is ASCII? [2 Marks] American Standard Code for Information Interchange. ASCII is a binary code that gives each character and symbol on the keyboard a unique binary

code. It allows computers to handle text.(d) Carry out the following binary arithmetic: [3 marks]

(i) 11+11 11+11100

(ii) 11 X 1111

X11

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11 11 1001

(iii) 110/11

{Each at a mark}

(e) Complete the following table and note that no marks will be awarded for answers with missing or unclear working. [ 6 Marks]

BIN DEC HEX

45

B6

11001

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