KCSE COMPUTER STUDIES REVISION KIT 2

Study the flowchart below and write an appropriate pseudo code of the same

Hint:
Before answering this question, you should determine which control structures to use. Since the condition comes before the statement and since there is looping/repetition, the for loop becomes relevant to use. 
Solution
For count = 1 to 10 Do
PRINT “ Enter a Number (N)’
INPUT N
Sum = Sum + N
END FOR
Display sum

Differentiate between optical and magnetic scanning techniques used for input and give two
examples in each case.

Optical scanners

• Capture data using light. A special type of concentrated beam of light is passed over the object, image or text which need to be entered inside the computer. The scanner converts it into digital form example:-

1. Optical mark recognition (OMR)
2. Optical bar recognition (OBR)
3. Optical character recognition (OCR)

Magnetic scanner

• Capture data by using magnetic technology i.e.

1. Magnetic ink character recognition (MICR)
2. Magnetic strip recognition

Name the three main types of human computer interface

1. Command line interface
   
2. Menu driven interface
   
3. Graphical user interface

Distinguish between a folder and a subfolder.

A folder - is a named storage area where the user can store related files to enable easy access
Sub folder – this is a folder inside another folder

Draw an illustration of a USB interface and explain its function.

USB port and its interface

A USB interface is a high speed bound transmission media capable of reaching a bandwidth of high 12MBPS and a low speed of 1.5MBPS. Its capable of transmitting data in either direction (bi-directional) and with a set of  two differentially driven data wires that can transmit data simultaneously.
USB interface has also the properties of hot plugging (when used as an interface, the computer user does not necessarily need to restart the computer for changes to take effect)
The USB is compatible with asynchronous and isochronous data transfer methods and is capable of carrying electrical power within its conductors; that is why its commonly used to charge portable devices.
The USB specification limits the length of a cable between full speed (or high speed) devices to 5 meters (16 feet 5 inches) and for low speed devices the limit is 3 meters (9 feet 10 inches).
It is commonly used to support I/O devices, including: keyboards, mice, game port, serial port devices, digital audio, printers, scanners, modems, joy sticks, and other telecommunication devices. 

More information on USB interface sourced from tyco electronics

Differentiate between parallel and serial port interface cables

Parallel Cables	Serial Cables
Transmit information simultaneously using a set of many conductors (wires)	Support transmission of data one bit at a time
Transmit data faster than serial cables	Are slow in transmission of data
Transmit data over short distances	Transmit data over long distances
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Explain the following storage disks
i) Zip disks
ii) Jaz disks

Zip disks
They are high capacity disks that resemble the floppy disks. They are slightly larger and thicker in size .It can hold as much as 250MB 
Jaz disks
They are small portable disks with high storage capacity of about 1GB to 2Gb.They are used to store data that require large storage

Give four examples of optical disks.

LS- 120 superdisk (SD)
Digital versatile disk (DVDs)
​Compact disk (CD)
Optical card
Optical tape

What do you understand by the following terms:
i) Industrial espionage
ii) Eaves dropping
iii) Surveillance

i) Industrial espionage
–Spying on your competitor to get information that you can use to counter or finish competitor. The aim is to get ideas on how to counter by developing similar approach or sabotage.
ii) Eavesdropping
-Tapping into communication channels to get information
iii) Surveillance
This is keeping of a profile of all computer activities done by another person

Differentiate between the following: 
i) surf/browse
ii) Hyperlink

Surf / browse
- It is the process of accessing internet resource like the web page and website
Hyperlink
It is a text on picture on an electronic document especially webpage that cause other web pages to open when the link is clicked.

Explain two functions performed by the UPS

1. Filters power by eliminating brownouts and power surges before it enters into the computer
2. Alerts the user when power goes off
3. Temporary stores power to let the user save his/her work before the computer goes off

List three data processing methods

1. Manual
2. Mechanical
   
3. Electronic

Define the term internet.

Internet is a large network of networks that covers the whole world and enables millions of computers from different organizations and people to communicate globally.

List four services offered by internet

1. World wide web
   
2. Electronic mail
   
3. Electronic commerce
   
4. Electronic learning

Differentiate between fourth generation languages and third generation languages

Third generation

• Used integrated circuits (ICs) to process data
• Were large in size compared to fourth generation language
  

Fourth generation

• Used VLSI-very large scale integrated circuits to process data
• Were smaller in size compared to third generation

State three communication methods without cables

• Microwave
  
• Satellite
  
• Radio transmission
  
• Microwave communication
  
• Infrared Communications
• Bluetooth and Zigbee
• Paging systems
• Broadband wireless access
• Cellular telephone systems
• Cordless Phones

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