KCSE COMPUTER STUDIES REVISION KIT 1

What is a COM device?

A COM device is a hardware component used to read and write data on microfilm or microfiche in form of  small microscopic images.

Differentiate between primary memory and auxiliary memory.

1. Primary memory access the processor directly while auxiliary memory does not
2. Primary memory stores data or information temporarily while auxiliary memory stores data permanently. 
3. Primary memory have higher storage capacity than auxiliary memory

A school intends to purchase a new software for exams analysis and financial management in the school accounts office.  List items that should accompany the software.

1. Documentation to provide the users with both technical and operational information about the software.
2. Certificate of authenticity to avoid acquiring pirated copies which is an offence or the pirated software may not function as expected.
3. Installation disk
4. Licence
5. Cash receipt 

Differentiate the following terms as used in computing:

a) Storage device and storage medium

• STORAGE DEVICE: This is the computer hardware that facilitates writing and reading of information in the storage media in a format that the computer  is able to understand and manage/manipulate.
• STORAGE MEDIA: This is the actual surface where data is stored.  The storage patterns and  technology will differ from one media to another in accordance to the media being used.

b) Removable storage media and fixed storage media.  

• Removable storage media is a storage media that can be moved from one computer to another and accessed by their specific ports or drives on the respective computers while fixed storage media are storage media that is inside the computer's system unit and can not be moved freely and easily from one computer to another. 
• Removable storage media is a storage media that can be moved from one computer to another and accessed by their specific ports or drives on the respective computers while fixed storage media are storage media that is inside the computer's system unit and can not be moved freely and easily from one computer to another.

​With the aid of a well labelled diagram, define the following terms as used on a magnetic storage media. 

Parts of a disk platter

Tracks

• Tracks are concentric circular regions on the surface of the disk;

Sector

• Sectors are pie-shaped wedges that intersect each of the tracks.

Cluster

• A cluster is a group of sectors 

​List four things that happens to a disk during formatting

1. All data in the disk is erased.
2. The surfaces of the disk are checked for any physical and magnetic defects.
3. New tracks and sectors are imprinted on the disk surface.
4. A file allocation table (FAT) is created to record where data is stored.

​List any four types of threats data is exposed to on a networked environment 

1. Viruses/worms.
2. Unauthorized access (Threats to Privacy and Confidentiality)
3. Alteration.
4. Fraud
5. Sabotage

List the three core principles of data security.

1. Confidentiality
2. Integrity
3. Availability

​Differentiate the following terms

i) Website and web portal

• Website - this is a group of related web pages or other resources located on a web server.  The first page on a website is called a homepage.
• Web portals - These are web pages which offer specialized services such as searching, e-mail, sports updates, financial, news and links to the selected websites.  A portal acts as a map or navigator around the internet since when a hyperlink on the portal is clicked, the linked web page appears. 

ii) Hyperlink and hypertext

• Hyperlinks - this is a link used to navigate from one webpage to another.  They are identified by a different colour of text (usually blue and underlined), when clicked upon the linked web page is opened.
• Hypertext: This is text linked together in a complex, non sequential web of associations in which the user can browse through related topics.  Or text which contains links to other texts. 

​List any four components of the system unit

1. The microprocessor chip (CPU)
2. Main memory chips
3. All support circuitry (motherboard)
4. The expansion slots where additional components can be plugged.

Differentiate  the following terms.

​i) DYNAMIC RAM and Static RAM

• DYNAMIC RAM (DRAM): Dynamic RAM have the characteristics of losing their contents with time and therefore they need to be periodically refreshed by a special generator circuit in order for the chip to retain data.
• STATIC RAM (SRAM): Information stored in the static ram don’t change as long as the computer is ON and therefore, they do not require electric current to be periodically generated to refresh the contents of this memory. Or
• DYNAMIC RAM (DRAM): Dynamic RAM chips are smaller and simpler in design.
• STATIC RAM (SRAM): Static RAM chips are larger and more complicated. 

ii) Mask ROM and PROM

• Mask read only memory:- The contents of the ROM are written by the manufacturer during the manufacturing.  Once the data has been written by the manufacturer it cannot be changed or their contents are only written once.
• Programmable Read only Memory (PROM):- This memory is supplied while blank and allows the user to record data on it only once and after the contents are written to it cannot be erased.

​Your parents have asked you to advice on the choice of printer for home use.  List three considerations that would help in this exercise.

1. The initial cost of the printer.
2. Maintenance cost of the printer
3. The compatibility of the printer to your computer hardware.
4. Availability and reliability of the printer i.e. the availability of its spare parts and ease of maintenance.
5. The printing speed
6. Printing mechanism i.e. impact or non-impact
7. Purpose of the printer i.e. office work, business, photo printing, mass printing etc.
8. Portability i.e. can it be moved from one place to another?
9. Enhancements capabilities like WI-FI, USB, SD Card slots, fax, Display board etc.

​Distinguish between a line printer and a page printer.

Line printers print one line of text at a time while page printers print a whole page at a time.

Modern office use a secondary storage device for backing up data on day-to-day basis.  Give two reasons why magnetic tapes are not a suitable choice and suggest the best storage device to use.

Reasons

1. It has a very slow data access time when compared to other forms of storage media.  and access to information on magnetic tape as it is sequential i.e you cannot go directly to an item of data on the tape.
2. It undergoes wear and tear; therefore it cannot be used as a day to day storage device.  It is usually used by large organisations for backup storage of data.
   
3. After a file is recorded on the tape, it is hard to update.
   

Best storage device:- Flash disk or external hard disk.

​Explain two features of a DVD that enables it to store more information than a CD-R 

1. The tracks on the DVD are densely packed compared to CD-R tracks.
2. Data can be recorded in layers on a DVD.

​State the importance of the following in programming

i) Assembler
It is a language processor that translates assembly language code into machine readable form. 
ii) Compiler
It translates the source code written in high level language into object code at once and this object code is usually executable on its own.

A form four class sat for an exam in eight subjects.  A student must get an average of 50% in order to pass.  A report is required that will show the name, marks obtained by each student per subject, the average mark and whether the student has passed or failed.
​
i) Write a pseudocode used to solve this problem

Start
        Enter student name
        Enter the eight scores for eight subjects
        Calculate the total and average as
        Total = a + b + c + d + e + f + g + h
        Average = Total/8
        If average > = 50
        Comment = pass
        else comment = fail
        Print student Name, Eight marks, Average score and comment .
Stop

​ii) Draw a flowchart for this report 

Flowchart

​System software can be divided into four types of system software.  List the four types of system software.

1. The operating system.
2. Firmware
3. Utility software
4. Networking software

​Define the term operating system as used in computing

Operating system is a set of complex programs that work together to control the execution of user programs and enables the user to access the hardware and software resources of the computer.  Or it’s the main /major program in the computer that control the execution of other programs and gives access to hardware resources.

​Briefly explain how the operating system manages the computer resources listed below.

i) The main memory
 The operating system may organise the main memory into blocks of sizes called partitions or page frames. All the opened programs are allocated a page frame in the main memory where only a section of the program instructions are stored as it awaits execution. Once the program part has completed executing, the operating system moves it back to the secondary storage device (hard disk) and another section loaded into the memory. This cycle continues until the entire program completes executing.
 
ii) The secondary storage devices
 The operating system manages the storage and retrieval of data on secondary storage devices. It also utilizes the free space on hard disks to enhance the performance of the computer by temporarily holding tasks on it that were in RAM ready for processing but have to wait for sometime.
 
iii) Communication devices and ports
 The operations of a computer depend entirely on the communication between various devices and programs in and out of the computer through sending and receiving messages from one another and from the processor. The operating system controls the overall communication process between various tasks and computers by setting the various components ready to receive or sent information and also controlling the flow of information and data around the computer during processing until the final results is communicated to the user through the output devices.
 External communication can be achieved by connecting an external device to a communication port using a communication medium such as cables or even wireless communication. 

The operating system have several functions in a computer, explain how the operating system performs the following functions.

i) Error handling
 The operating system has many ways of alerting the user of errors he/she makes. The operating system being a manager that oversees all the activities of the computer, it monitors all the user activities. Due to this, the operating system has the ability to identify errors made by the user and where possible suggestions on how to correct the errors made. On the other hand, the operating system monitors the status of the computer system by performing error checks on both hardware and software.
 
ii) Resource control and allocation
The operating system uses the IRQ number to identify the resource being requested by processes, poor resource allocation would result to an undesirable condition referred to as deadlock (this is whereby a process holds the requested resource and fails to release it, yet it is requesting for a resource held by another process) 

​Distinguish between a command line based operating system and a menu driven operating system

Command-line based operating system was used by the first operating systems which only provided the user with a black screen to type a command at the prompt. The computer reads the typed command from the command line and executes it while a menu driven operating system provide the user with a list of options that represent computer commands for the user to choose from.

​Computer students visited a local TV station in the city and noticed that the News presenter in the studio was communication in real time with other four reporters through a webcam and a microphone connected to a notebook PC nearby.  The live images of the other reporters were projected on a white board mounted in the studio. 

i) Describe this type of communication
Video conference - It is whereby members of a particular group are able to hold meetings/discussion in real time mode though each individual is  far apart geographically.
ii) State any TWO advantages and ONE disadvantage of this type of communication. 
Merits
​ - It minimizes the travelling cost incurred by members.
 - It does not require large room for holding meetings (saves on space)
 Demerits
 - Requires that each members must have ICT equipment that may be costly.
 - There must be constant connection to the net for its effectiveness.  
b) Currently there is a shift in technology towards digital technology from analog. State any THREE advantages of digital technology over analog technology.
- There is quality in the images being transmitted.
- Digital transmission is cheaper than analog in terms of frequencies.
- It requires less equipment for its operation (one can give signal to a service provider for distribution) 
c) i) Documentation is usually not considered as a system development stage. Why is this so?
This is because every stage in structured approach to system development (SDLC) is usually documented before proceeding to the next stage. 
ii) Differentiate between internal and external documentation.
Internal documentation - These are comments that the programmer gives within the source code explaining particular lines of code. They are non-executable. 
External documentation - These are written materials that the analysts come up with detailing how the system is  installed, run and maintained. They are in the form of manuals. 
iii) State THREE types of documentations available at the end of the programming  project.
User oriented documentation
Programmer oriented documentation
​Technical documentation

​Distinguish between absolute cell reference and relative cell reference

Absolute reference - it is a reference that refers to specific cells within the worksheet and therefore  even if copied to other cell, they do not change.  They use the dollar sign
Relative reference - This is whereby the cell addresses used in a formula or function keeps on changing when copied to other cells within the worksheet.

​A small garage owner wants to use computer software to calculate  his staffs wages and also to give quotes to customers for repair work done on their car.  Describe four benefits to be gained from using spreadsheet software to solve these problems. 

• It is faster in calculations once the expressions have been designed.
• It adjusts the results of a formula/function automatically (automatic recalculation)
• Outputs from these software are usually neat and presentable.
• They utilize powerful aspects of computer like speed in performing their operations.

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