COMPUTER STUDIES QUESTIONS WITH ANSWERS
Explain the following data communication modes:Â (a) simplex (b) half-duplex (c) full-duplex14/11/2022 Explain the following data communication modes: (a) simplex (b) half-duplex (c) full-duplex (a) Simplex communication is the mode in which data signals flow in one direction only in a communication channel and cannot flow back in the opposite direction. (b) Half-duplex communication is the mode in which data signals flow in both directions of the communication channel, but they do so in one direction at a time. (c) Full-duplex communication is the mode in which data signals flow in both directions in a communication channel simultaneously.
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Explain the importance of repeaters in a communication system. Different mediums have different attenuation rates. To avoid signal loss in the medium due to attenuation, repeaters are introduced at appropriate points on the network (attenuation points) to receive the weak signal, clean it, amplify it then send it over to the next section of the medium in the network.
When data is being transmitted from a source to a destination, it could face challenges that may cause it to get lost. Highlight these challenges.
(a) State the name used for this technique.Multiplexing Using an illustration, depict how this concept worksA multiplexer carries many data signals on the same physical transmission channel from a source while a demultiplexer separates the combined signals at the destination
Differentiate between the following:(a) Signal modulation and demodulationModulation is the process of superimposing a low frequency (low power) data signal on a high frequency (high power) carrier signal to enable its transmission over long distances in the medium. Demodulation, on the other hand, is the extraction of a data signal from a modulated carrier signal which has been used to transmit over the network. (b) Modulation rate and baud rate Modulation rate is the term used to express the performance of a modulating circuit. It shows the rate at which the modulated signal is processed to represent data. It is measured in pulses per second or the baud hence, it also known as baud rate. (c) Bandwidth and throughputBandwidth is the maximum rate at which a transmission channel can convey data. It is measured in bits per second (bps). On the other hand, throughput is the instantaneous rate at which a particular channel is transmitting data, and may be swab equal to or lower than the maximum bandwidth available. (d) Baseband and broadband signalsA baseband signal takes the entire bandwidth of the physical channel; hence, it is transmitted alone. A broadband signal, on the contrary, divides the physical channel into many frequency channels; hence, it allows many signals to be transmitted through the medium in a multiplexed manner.
A signal wave has three salient properties: frequency, wavelength and amplitude. Describe each one of them.
Differentiate between a stand alone computer and a networked computer. A stand alone computer is one that is used alone and has no connection to a network while a networked computer is connected to a local or wide area network and can share resources with other computers on the network.
What is signal encoding? Signal encoding is the process of representing a data signal using different voltage levels and polarities in a network circuit. A voltage level of +5 volts may mean a one (1) while a -5 volts level may mean a zero (0). In this case, the polarity of the signal, (+) or (-), indicates the different meanings of the signal.
What is a data signal? A data signal is a voltage level in a computer network circuit which represents the presence of data ready for transmission, reading or storage.
What is data communication? Data communication is the process of transmitting encoded data from one point to another in a computer network. In most cases, the data is encoded using analog or digital means for transmission or storage.
What is a computer network? A computer network is an interconnection of computers through a communication medium that enables the computers to exchange data or information (communicate).
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COMPUTER STUDIES PAPER 1 REVISION KIT 2022 TERM 2 MODEL17092022002![]()
Musato high school wanted to setup a network connectivity to be used in school. Mention three internet connectivity requirement that the school must have to get the connection.
Using relevant examples distinguish between a formula and function.
John is a first-year student at JKUAT. He is expected to login his student portal to access online assignments. Mention three ways in which he would prevent virus from infecting his computer.
Describe the term portability as used in the following context.Hardware
Mention three factors to consider when choosing an ISP for internet connectivity.
DESCRIBE FOUR WAYS IN WHICH ICT CAN BE USED TO IMPROVE HEALTH CARE PROVISION
PETER USED A COMPACT DISK RECORDABLE TO SAVE HIS WORK. ½ OF THE DISK WAS USED TO STORE VIDEO FILES WHILE ¼ OF THE REMAINDER WAS TO SAVE AUDIO FILE. NOTE THAT CD-RECORDABLE IS 700MB. CALCULATE THE REMAINING SPACE IN BYTES.Video =0.5 x 700= 350 …………………… ½ mark
Audio = 0.125 x 700=87.5 ………………… ½ mark Total = 437.7 …………………… 1mark Remaining spaces (700-437.5) = 262.5MB ………… 1mark Program Control Structuresprogram control structures are blocks of statements that determine how statements are to be executed, in structured programming languages, there are three control structures namely; sequence, selection and iteration (looping) SequenceIn this structure, the computer reads instructions from a program file starting from the first top line and proceeding downwards one -by -one to the end. This is called sequential programming execution i.e. SelectionIn selection control, execution of statements depends on a condition which is either a true or false There are four types of selection controls. Namely:
The IF....THEN selection is used if only one option is available. All other options are ignored Format: IF <condition> THEN Statements; ENDIF IF....THEN....ELSE This type of selection is suitable where there are two available options General Format IF <condition> THEN Statements; ELSE Statements; EndIF Nested IF Selection This type of selection is used where two or more options have to be considered to make a selection. General Format IF <condition> THEN statements ELSE IF <condition> THEN statements ELSE IF<condition> THEN Statements ELSE Statements ENDIF ENDIF ENDIF CASE Construct This is an alternative to the Nested IF especially where there are several options to choose from. Its preferred because it reduces the many lines of code. However, the boolean expression for the case selection can only be expressed using integers and alphabetic characters only. The General format should be CASE integer OF or CASE Char OF Example: Case x of label 1: statement 1 label 2: statement 2 label 3: statement 3 . . . label n: statement n-1 Else statement Endcase Iteration (looping)Iteration is also referred to as looping or repetition. Its designed to execute the same block of code again and again until a certain condition is fulfilled. The three main looping controls are:-
The "WHILE" loop is used if a condition has to be met before the statements within the loop are executed. General Format WHILE condition DO statement ENDWHILE The REPEAT....UNTIL loop The REPEAT....UNTIL loop allows the statements within it to be executed at least once since the condition is tested at the end of the loop. General Format REPEAT statements UNTIL <condition> The FOR Loop
The FOR loop is used in circumstances where the execution of the chosen statements has to be repeated a predetermined number of times. General Format //pseudocode for 'FOR" loop that counts from the lower limit FOR loop variable = lower limit to upper limit DO statements ENDFOR |
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