1. Give definition to information and communication technologies

Information Communication Technology (ICT) includes all the technologies used for communication of information. These include devices such as computers, internet and intranet, local and wide area networks (wired and wireless), voice mail, e-mail, audio visual systems, compact discs and video discs, broadcast receiving systems and telecommunication systems, media, printed media, virtual learning centers, instructional software, education television, satellite communication, cable TV, conventional and interactive radio used in teaching and learning.

Information and communication technologies (ICT) is term that covers all advanced technologies in manipulating and communicating Information. Information Technology means the processing and distribution of data using computer hardware and software, telecommunications, and digital electronics.

ICT three main components are

– Computers; used to process data into information,

– Communications networks; transmission of information,

– Know-how; the technology used for the transmission

2. Describe computer systems

A computer is an electronic system that can be instructed to accept, process, store, and present data and information. It is made up of two component parts: hardware and software.

– Hardware is a general term for the physical components that make up a computer system, for example keyboard, mouse, monitor, processor, circuit board and so on.

– Software is a general term for the programs that control the computer system. Software is any set of instructions that tells the hardware what to do and how to do it.

There are two types of software:

-systems software: programs that allow the hardware to run properly, e.g.operating systems

-applications software: programs that allows the user to do specific tasks, e.g.

Main components of computer systems:

- input devices: keyboard, mouse

- output devices: monitor, printer

- secondary storage devices: DVD R/W drive, removable hard drive.

3. Give definition to Operating system.

An operatingsystem isthe mostimportantsoftware thatrunson a computer. Everygeneral-purposecomputermusthaveanoperatingsystemtorunotherprograms. Italsoallowsyouto communicate withthecomputerwithoutknowinghowtospeakthecomputer'slanguage. Itmanagesthecomputer's memory, processes, andallofitssoftware and hardware, i.e. managesalltheotherprogramsin a computer. The other programs are called applications or application programs.Most of the time, there are many different applications  running at the same time, and they all need to access your computer's central processing unit (CPU), memory, and storage. Theoperatingsystemcoordinatesallofthistomakesureeachprogramgetswhatitneeds.

The structure of OS consists of 4 layers:

• Hardware (Hardware consists of CPU, Main memory, I/O Devices, etc. );

• Software i.e. Operating System (Software includes process management routines, memory management routines, I/O control routines, file management routines);

• System programs (This layer consists of compilers, Assemblers, linker etc.);

• Application programs(This is dependent on users need).

Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).

Classification of Operating systems

• Multi-user

• Multiprocessing 

• Multitasking 

• Multithreading

• Real time

Allmodernoperatingsystemsuse a graphicaluserinterface, or GUI (pronounced gooey). A GUI letsyouuseyourmousetoclick icons, buttons, and menus, andeverythingisclearlydisplayedonthescreenusing a combinationofgraphics and text.

Eachoperatingsystem's GUI has a differentlookandfeel, soifyouswitchto a differentoperatingsystemitmayseemunfamiliaratfirst. However, modernoperatingsystemsaredesignedtobe easytouse, andmostofthebasicprinciplesarethesame.

Thethreemostcommonoperatingsystemsforpersonalcomputersare MicrosoftWindows, AppleMac OS X, andLinux.