Network - Introduction

Introduction to Network

Advantages of Network


1. (a) Explain what is meant by 'computer network'.


Computer Network is a group of two or more computer systems linked together.
A computer network is a group of computers and other computing hardware devices, e.g. printers, that are linked together through communication channels either ; cables or  Wi-Fi.


  (b) Explain what is meant by a 'local area network'.


The computers are connected close together in a limited area or on a single site. e.g. in the same building, house office or school building.


(c) Describe two ways in which the computers can communicate with each other.
To communicate computers can be physically connected by cables, over Wi-Fi, home routers with built in WAP functionally or even a wireless access point allowing wireless devices to connect to the network.


2. Describe the advantages to the users of creating a computer network rather than all users using stand-alone systems.
With a computer network each user does not need their own device connected directly to their computer as devices (printers) can be shared. Files can be shared across networks with other users, so there is no need for storage mediums (CD, DVD, USB, Memory stick). Also, Users are able to communicate and work collaboratively on the same document as well as sharing the same internet connection using a router which directs traffic to the correct users.
Users can access their own personal files from any computer giving greater flexibility.
If all data is stored centrally it makes it easier to back it up. A network provides greater security with usernames and passwords, monitoring the activity of each user but also prevents illegal installation of software. Having a computer network is usually cheaper as you buy licences for a network software rather than buying a version for each stand-alone computer.
3.Sugguest some disadvantages of creating and using a computer network.
Creating and using a computer network may be expensive with the cost of extra hardware and infrastructure. Sharing may create disadvantages, some users may use up too much bandwidth creating problems for other users. Malfunctions could cause loss of files and incompletion of work if data is stored on a central file, creating a higher risk of viruses spreading and easier for hackers as they don't have to search for files on all the stand-alone computers.

Functions of an operating system

Operating Systems



Explain what is meant by an 'operating system'

• The operating system is a software necessary to run all computing devices. It deals with controlling all aspects of the computer e.g. controls and organises the general operation of the copmuter. The OS makes it easier to write applications. It sits betweeen applications and hardware on the computer.
• Kernel is the lowest level of OS and controls the hardware

When is the operating system loaded?

• The operating system is part of the computer booting and loading up. when you turn the computer on the operating system must be loaded from the Hard Disk into RAM befrore the computer can be used.

List some commonly used operating systems:

Operating system	Use
Windows		Personal computers
Linux		Personal computers
MacOS		Macs
UNIX		Mainframes
Symbian, Androids		Mobile phones

Explain how the operating system controls the software and hardware on the computer

• The operating system manages communications between software and hardware. For example: 

                 - Loading and saving data and programs

                 - Communicating with peripherals such as a mouse or a printer

                 - Organizing data stored on a hard disk

                 - Displaying information on the VDUMessages are sent to and from the operating system where the task is read and performed by the operating system

Describe two types of user interfaces provided by the operating system

• Graphic User Interface (GUI) - icons that load your programs that show up on your desktop, colours that set the background colour
interacts with computer using a pointing device (e.g. mouse or trackball). Most popular form is a Windows, Icon, Menu and Pointer (WIMP) system. The features  include:

Window : An area of the screen which is used to display a particular program or piece of work. Many windows can be displayed on the screen at the same time. e.g.

Icon : An informative picture / symbol displayed on the screen which the user chooses to select an action. Icons can usually be used to represent software packages, documents and hardware devices. e.g.

Menu : A list of options which the user can pick from. Menus can be pull-down (selected from a menu bar at the top of the screen) or pop-up (selected by pressing a mouse button). e.g.

Pointer : A symbol such as an arrow which is moved by a pointing device and can be used to select objects.

Advantages

Disadvantages

Most operations are self-explanatory so that you do not have to remember lots of commands. Some operations are much easier using a GUI with a pointer. e.g. selecting text or drawing pictures. Often you can have more than one program running at the same time, each of them using different windows. Often GUIs are WYSIWYG. What you see on the screen is what you get if you do a printout. Often with a GUI many programs use a similar interface, so it is easier to learn how to use a new program. Most GUIs provide good help facilities.

GUIs can take up a lot of memory and need to be run on a fast computer. If you have a slow computer, a GUI may work slowly or not at all.

• Command User Line Interface (CUL) - interaction with a computer using a command line interface usually follows these two steps :
  • The user types a command e.g. "dir".
  • The computer carries out the command and displays its results.

Advantages	Disadvantages
An experienced user who knows a package well can enter commands quicker than he could select options using lots of menus. Can be used on a computer which has very little memory and is slow.	It is very difficult to remember all the possible commands and exactly how they should be typed. Error messages are not usually very helpful.

Explain what is meant by a 'multitasking operating system'


A multitasking operating system is allowing the computer to perform more than one task/program at once.


Explain the difference between client and server operating systems

• Client Operating Systems - optimized to do everyday tasks like word processing, internet browsing
• Server Operating Systems - highly customized and optimized for hosting demanding applications

UNIT 2 - Software

UNIT 2 - SOFTWARE

Software is the program that runs on a computer

-          Includes: Application software and system software – operating systems, drivers, film ware, servers

-          System software – controls and makes use of hardware

-          Applications software – programs which world tasks. Microsoft word

-          Software is written by programmers using various programming languages

Alan Turning thought of a device which will do any task when given the instruction to do so

-          Instructions are loaded into the RAM from the hard drive and fetched – decoded and executed by the CPU. These instructions are a program i.e. software

-          CPU understands Binary – machine code long winded and difficult. So programmers use high level

Software

-          The operating system – necessary to run all computing devices

Functions of The operating system

-          Sits between your applications and hardware of your computer

-          Deals with controlling all aspects of the computer

-          Makes it easier to write applications

-          Kernel is the lowest level of OS and controls the hardware

Functions – Manages hardware

-          Manages hardware and software resources of the system

-          In a desktop computer theses resources include: processor, memory, disk space and more

- EG; when you wish to save a document the application passes the document to the OS

 

- OS needs to use different instructions to save to a hard disk compared to solid state drive

 

- OS uses special software called device driver to translate specific instructions

Each different piece of hardware will have a device driver to communicate between the OS and hardware.

 

Device drivers are used to communicate

Peripheral Management

-          Computer has peripherals in order to input output and store instructions data. The signal which controls them is a device driver controlled by the software. Each peripheral has its own driver depending on manufacturer there are some genetic device drivers ion windows 7/8 

-          Application software doesn’t need to know about the devices it passes on requests from the users to the program

-          Interpret signal id generally by a program which tells the Operating System to stop a program using a device and make the CPU do a task for another programme with the device

User setting

-          Applets – a small application that does a single task

Firm ware

-          The initial starts up before device drivers are loaded on. This is stored permanently on ROM chips e.g. BIOS- basic input output system which does initial start-up of a computer.

-          Also runs on a simple devices such as TV remote or camera

Server

-          The word server applies to the hardware (the computer) and software

-          Server software resounds to the requests of other programs (clients). It is used on the internet and on smaller networks like we have in school e.g. when we ask to print – the server software processes the request and delivers the data to the client

-          Any computer can be a software, just install software data

Functions

Multitasking

-          The operating system controls multitasking making it look like the computer is running more than one program at once

-          It does this by switching between programs very quickly

-          The #CPU is so fast there are times when the RAM can’t keep up (video buffing) so the CPU is instructed by the OS to do something in this time

Memory management

-          The OS controls the memory management allocating RAM space to programs

-          Determines how much memory each app had and what to do if the memory becomes full

-          Manages virtual RAM

-          Tracks where data and programs are at any one time to make efficient use of the memory and ensure nothing is lost

Security

-          OS must protect processes from each other and users=s from each other because PCs are used by multiple users at home or on a network and on the internet.

-          Manages

-          Tracks who owns each file and what privileges the user has on each file/folder e.g. admin rights

-          Passwords to login allow you to protect your phone from other users but also allow you to use networked computers on your own profile.

 User Interface – how you interact different types

-          OS provides a user interface

-          This is what the other user sees when they wish to use the computer system

-          There are different types of user interfaces, each with their own advantages and disadvantages

User interface – command line interface

-          This is used to be the only way to operate a computer

-          Commands are typed in at a prompt to run programs or perform actions

-          Does not need a powerful computer

-          Fast to get things done

-          Not suitable for beginners as you need to know the commands before you can operate the computer used by technicians

Menu

-          Often seen on devices where the input device is limited TV remote

-          As all the options are there to be seen Simple and easy for novices

-          Simple to navigate and easy to determine what to do

Graphical user interface GUI

-          Popular with ease of use

-          Is the way we most often control the computer

-          Programs run in windows, icons represent files and apps

-          Actions may have metaphors dragging a file on to the trash can mean delete the file for example,

-          Intuitive and easy for beginner

Voice recognition

-          Still evolving but is becoming more widely used e.g. call centres ask the user to say numbers and yes/no. apple iPhone has voice recognition as part of OS – Siri

Windows

-          Windows Operating System currently 8.1 keeps the GUI and all applications looking similar so that a user can easily use them. They all use code that is part of windows itself

-          It has a huge range of capabilities, far greater than OS itself

MAC OS

-          On PC this is currently Yosemite. This is based on a UNIX system and has led to the iOS for mobile devices. It is a proprietary system which has enabled new ways of thinking about how a user interacts with the OS

-          More reliable artists media

LINUX

-          Open source range of OS’ based on the UNIX Kernal. UNIX works on command line but the new versions of LINUX run a GUI. It is a small OS and is therefore fast and uses less memory. It is very versatile and is used on servers and mobile devices – ANDROID

How RAM affects performance

1 (a) ‘RAM’ and ‘ROM’ are acronyms. State what the letters RAM and ROM stand for.

• RAM - Random Access Memory
• ROM - Read Only Memory

(b) State the differences between RAM and ROM.

• RAM a form of volatile memory, it loses all data when power is turned off, ROM is not volatile.
• ROM is read only, it cannot be changed, data can be written to the RAM by the computer.

(c) Explain why ROM is required by the computer.

• ROM is needed by the computer so instructions can be remembered by the computer (e.g. configuration settings). BIOS - basic input output system - is stored on ROM so the computer has boot up instructions.  

2. Explain the function of RAM in a computer system.

• RAM is a physical type of volatile memory. It sends instructions to and from the CPU inorder to load documents and programs. when programes are open they are, loaded onto the RAM. RAM allows you to open a number of documents at any one time - however this does slow down your system. To over come this, a bigger RAM should be installed, most computers come with 1-4GB of RAM installed.

3. Explain what happens when there is not enough RAM to store all of the required data

• When the RAM is full data is swapped out from the CPU on to a hard disk, this is known as Virtual memory. The least used page is most likley to be swapped out, but if it is referenced it will be swapped back for another file/page.

4. Explain how inserting more RAM in a computer affects its performance.

• With more RAM in a computer more instructions can be prosessed on the RAM meaning that less swapping, in and out, of data to the hard drive is needed.  Constant swapping in and out of data slows down the speed at which programs run. so, increaseing RAM increases the speed of the operating system aswell as increaseing the amount of programs that can be ran at once.