1. Application
2. Presentation
3. Session
4. Transport
5. Network
6. Data link
7. Physical

• Network operating systems
• Protocols

• A physical file contains the original data whereas a logical file does not contain any data
• A physical file contains one record format while a logical file can contain up to 32 record formats
• A physical file can exist without a logical file while a logical file cannot exist without a physical file

1. a) Based on Deutro-Isaiah, describe the Messiah. (7mks)

The Messiah would be despised/ rejected

The Messiah would be treated harshly/ arrested/sentenced to death

The Messiah would be reconciling people through His suffering

The death of the Messiah would bring forgiveness of sins of humankind

The Messiah would endure suffering/humiliation without complaining/ would suffer innocently

The Messiah would have nothing attractive

The Messiah would be humble/simple

The Messiah would be highly honored

The Messiah would succeed in His work

He would be despised, rejected, wounded oppressed and afflicted 

He endured pain and suffering which would have been ours. 

Because of our sins he was wounded 

We are healed by the punishment he suffered He was treated harshly but he never said a word 

He was put in the grave with the wicked 

He was buried with the rich even though he did not commit a crime 

He took the place of many sinners and prayed that they might be forgiven.

 A single executable file is produced 

The executable program is portable between machines

The program source code is not available

Code can be optimised/made more efficient 

Entire source code file is converted at once

No special environment is needed to execute the code 

It creates object/machine code

Error report is provided at the end of the compilation

• Artificial intelligence
• Parallel processing
• Natural language processing
• quantum computing

Job scheduling/Process scheduling                                                                                              (2mks)

• Operating systems allocate tasks/processes/jobs to the CPU using priority and FIFO principle

 Memory management                                                                                                                  (2mks)

• OS allocates and de-allocates memory spaces to processes loaded into the RAM
• Swaps processes between main memory and virtual memory created in the secondary storage

(a)

– webcam
– speakers
– microphone
– broadband modem

(b)

– use of CODEC (converts/compresses analogue data into digital data)
– echo cancellation s/ware (allows talking in real time/keeps everything in sync)
– compression s/ware for video/audio
– s/ware to access broadband/networking

State the characteristics of each of the following network topologies (KCSE COMPUTER STUDIES 2021 )

i) Mesh Topology  (2mks)

• a host/node is connected to one or multiple hosts
• a   host/node in point to point connection with every other host or a few hosts
• hosts/nodes in mesh topology also work as relays for other hosts which do not have point-to-point links

(ii) Ring Topology (2mks)

• each host/node connects exactly to two other hosts
• data travels around the ring in one direction through all intermediate hosts
• failure of any host results in the failure of the whole ring

• Processor X is likely to process instructions more efficiently as firstly it has the i7 CPU which is a faster processor as well as the quad core which processes quicker and the higher GHz versus Processor Y

• System software that analyses, configures, optimises and maintains a computer system

(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

• mirrored hard disk/hot standby/second computer
• re-run the old master file with the transaction file

• Hierarchical model  - Records in the database can be related to one parent only but can have more children records
• Network database model - a child record can be linked to  multiple parent records
• Relational database model - organizes data into tables that can be linked or related based on data common to each.

• College authorities are the experts in the problem
• A system Analyst is an expert with computers
• The two need to pool resources to come up with a clear definition
• Agree on the outcomes so that when the system is , there are a set of criteria to judge it by

• This approach causes minimum disruption

• Extra bit on each data-byte that
•  Does not transmit data
• Makes the number of ones in a byte always even or always odd
• Error in the transmission of a bit will make the even/odd wrong
• The problem of two errors in one byte not being found
• Parity block

Advantages

• on-line catalogues can be viewed
• much larger choice of products
• product reviews obtainable before purchase
• orders placed over internet any time day or night
• download software purchased straight away
• good and services usually cheaper on the internet
• programs that can search for best price/cheapest
• very fast placing an order has been placed as customer name, address
• and credit card details are stored so no need to re enter
• buy goods from anywhere in the world
• no need to go to shop/save travelling time

Disadvantages

• spam
• need a credit card to shop on-line/not everyone has a credit card
• hackers could retrieve credit card numbers and use them to buy goods
• security fears - of giving credit card number over the internet/fraud
• goods must be delivered/can not have the goods immediately
• can not touch/handle/see the goods

• Processor

• Used to resize the image
• Used to rotate the image
• Used to move the image