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

•  map IP addresses to names and criteria
• To map directory services
• Maintain directory of domain names
• To map URL (web address) to IP address

1. Operating system manages the computer hardware thus without it the programs cannot communicate directly to the hardware
2. Provide a user interface through which a user can give instructions to the computer. Without a user interface, it would be difficult to load or run programs
3. other programs depend on the operating system to load them into the memory , allocate resources and schedule processor time, Without operating , there would be nothing to co-ordinate the execution of multiples programs
4. The OS organizes data in files and directories, making it possible for programs to save, retrieve, and modify data.
5. Without it, programs wouldn’t know where or how to store data.
6. The OS controls access to files, memory, and devices, ensuring that one program doesn’t interfere with another.

• It refers to a system software that provides a platform for installation and execution of an application software and also manages the computer hardware

Taking a four-digit 0  binary number i.e (0000)2

In ones complement this is  1111

In twos complement this becomes 1111+1= 0000

So, It is clear that 0 and negative zero is the same in twos complement while in ones complement they are two different values

• two's complement has only one value for zero

1. Hardware failure
2. Corrupted software files
3. Hacking into the system
4. Power failure

• camera
• microwave
• washing machine
• video recorder
• fridge
• sewing machine
• air conditioning
• games console
• electronic game electronic toys
• rice cooker
• dish washer
• TV
• alarm clock
• radio

• switches can send and receive data simultaneously - they are full duplex
• a hub is half duplex- only one host can communicate at a time.
• a hub broadcast signals to all computers connected in a network while a switch directs data to its intended destination

– faster communications now widely available
– safety reasons, e.g. increase in terrorist attacks on international flights
– reduced transportation/accommodation/hardware costs
– environmental issues, e.g. reduced carbon footprint
– increase in multinational working

• Installing the latest versions of antivirus software
• Avoiding downloads from untrusted sites
• Scanning removable storage media for viruses before use
• Scanning attachments for viruses before opening or downloading

• A computer is an electronic device that operates (works) under the control of programs stored in its own memory unit
• An electronic device that accepts data, as input and transforms it under the influence of a set of special instructions called programs, to produce the desired output (referred to as information)

• A compiled program will only execute on a processor of specific type/family/with same instruction set
• A program run using an interpreter can execute on a computer with any type of processor;

Blackout: This is unexpected discontinuation of power supply in the laboratory.

Power sag: Sudden drop of voltage levels that lasts less than a second.

Transients/ surge: High voltage flowing.

Brownout: Partial blackout where there's low voltage flow.

• It transfers data signals from one node directly to another in the network without broadcasting

• Is an integration of sound, text, graphics, and video to convey information

• Recommendation on whether to continue or abandon the project
• Methods used to collect data
• benefits and limitations expected
• the technology required to develop and maintain the project
• Installation and running cost
• Time limit

(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

• Real-time OS reads information from input devices and must respond within a short duration of time to ensure correct performance
• Distributed OS distributes computation among several physical processors which do not share memory or clock

• It ensures that each row has a unique and non-null primary key