What Is Computer Software, Application Software And Systems Software?

A computer’s software refers to a program (or a group of programs) which give a computer instructions on what to do and how to operate. Software programs can provide one main task, or multiple main tasks.

As an example, a program designed to edit digital photographs has one key task (i.e. to allow for editing of photos) – naturally it would have numerous sub-tasks though (i.e. red eye removal, color correction features, resizing and cropping/cutting of an image).

On the other hand, a computer’s operating system (a complex piece of software which basically handles and runs the entire computer) would carry out many main tasks – for example handling input and output (i.e. the user typing in with a keyword, or audio coming out of speakers), memory allocation, managing the computer’s hardware components (these are the electrical components which power a computer) and much more.

Software can be grouped into roughly two groups: application software and systems software. Essentially, software which facilitates just one main task (for example, photo editing software as in the above example) would be counted as application software. This is contrasted to systems software which refers to complex, multi-task programs which help to run the entire system – such as an operating system.

These two main groups of software are discussed in more detail below:

Application Software

This is software which is installed on an operating system (See “Systems Software” below for more information). As mentioned above, this type of software tends to perform just one main task. Another example of application software would be a website browser: this is the program which you are probably using right now to view this article. Examples of a browser include Internet Explorer, Google Chrome and Mozilla Firefox. In short, their main task/function is to facilitate you in surfing the internet.

Other types of application software are as follows:

  • Word Processing – this type of software allows you to type up documents and letters. Examples include Microsoft Office Word and Open Office.
  • Antivirus Software – this type of software helps protect your computer system against malicious threats such as viruses and malware. Examples include Norton Antivirus, Kaspersky Antivirus and AVG Anti-virus.
  • Photo Editing – this type of software can be used to edit and manipulate photos and other digital images in various ways. Examples include Paint.net, Corel PaintShop Pro and Adobe Photoshop.

Systems Software

This type of software is quite accurately described as being at the very core of any computer system. Without systems software, a computer could not really function. In short, it manages every aspect of a computer system – from how the hardware interacts with the software (‘drivers’) to giving the user an interface and platform to interact with the system (‘operating system’). The operating system – or ‘OS’ – is the software that loads up after your computer is switched on. It’s where all application software is installed on. Examples of an OS include Microsoft Windows (XP, Vista, 7 etc), Linux (Ubuntu, CentOS) and Apple Mac OS X.

Other types of systems software include device drives (these make the hardware components function correctly with the software and computer system) and utilities (these are also called ‘utility tools’ and they help monitor, maintain, check and analyze different parts of a computer; such as ‘Task Manager’ and ‘Disk Defragment on Windows OSes).

Wide Area Network (WAN)

Types and Characteristics of WANs

What is a WAN?

There are two prevailing definitions of a Wide Area Network (WAN). The book definition of a WAN is a network that spans large geographical locations, usually to interconnect multiple Local Area Networks (LANs). The practical definition of a WAN is a network that traverses a public network or commercial carrier, using one of several WAN technologies

What are its Main Components?

The main components for a WAN are routers, switches and modems. These components are described below in the hardware section.

CPE – Devices on the subscriber premises are called customer premises equipment (CPE).

The subscriber owns the CPE or leases the CPE from the service provider. A copper or fiber cable connects the CPE to the service provider’s nearest exchange or central office. This cabling is often called the local loop, or “last-mile”.

DTE/DCE – Devices that put data on the local loop are called data circuit-terminating equipment, or data communications equipment (DCE). The customer devices that pass the data to the DCE are called data terminal equipment (DTE). The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud.

Hardware

In a WAN you will need various types of hardware components for it to function. The typical items of hardware that you will need in a WAN are:

Router – An electronic device that connects a local area network (LAN) to a wide area network (WAN) and handles the task of routing messages between the two networks. Operates at layer 3, and makes decisions using IP addresses.

Switch – A switch is a network device that selects a path or circuit for sending a unit of data to its next destination. Operates at layer 2, and uses MAC addresses to send data to correct destination.

Modem – Short for modulator/demodulator, a modem enables a computer to communicate with other computers over telephone lines. Operates at layer 1, where signals are converted from digital to analogue and vice versa for transmission and receiving.

Wan Standards

WANs operate within the OSI model using layer 1 and layer 2 levels. The data link layer and the physical layer. The physical layer protocols describe how to provide electrical, mechanical and functional connections to the services provided by the ISP. The data link layer defines how data is encapsulated for transmission to remote sites.

Encapsulation

Encapsulation is the wrapping of data in a particular protocol header. Remember that WANs operate at the physical layer and the data link layer of the osi model and that higher layer protocols such as IP are encapsulated when sent across the WAN link. Serial interfaces support a wide range of WAN encapsulation types, which must be manually specified. These types include SDLC, PPP, Frame delay etc. Regardless of WAN encapsulation used it must be identical on both sides of the point to point link.

Packet and Circuit Switching

Circuit switching and packet switching are both used in high-capacity networks.

The majority of switched networks today get data across the network

through packet switching.

Circuit-switching is more reliable than packet-switching. Circuit switching is old and expensive, packet switching is more modern.

General Routing Issues

What is a Routing Protocol?

A routing protocol is a protocol that specifies how routers communicate and exchange information on a network. Each router has prior knowledge of its immediate neighbours and knows the structure of the network topology. The routers know this because the routing protocol shares this information.

Protocol

RIP (Routing Information Protocol) was one of the most commonly uses protocols on internal networks. Routers use RIP to dynamically adapt changes to the network connections and communicate information about which networks routers can reach and the distance between them. RIP is sometimes said to stand for Rest in Pieces in reference to the reputation that RIP has for breaking unexpectedly and rendering a network unable to function.

Routing Algorithms

Distance Vector

This type of routing protocol requires that each router simply inform its neighbours of its routing table. The distance vector protocol is also known as the bellman-ford algorithm.

Link State

This type of routing protocol requires that each router maintain a partial map of the network. The link state algorithm is also know as Dijkstra’s algorithm.

IGRP

IGRP is a type of distance vector routing protocol invented by cisco used to exchange routing data in a autonomous system. Distance vector protocols measure distances and compare routes. Routers that use distance vector must send all or a portion of their routing table in a routing update message at regular intervals to each neighbour router.

Addressing and Routing

What does routing mean?

Routing is the process of deciding how to move packets from one network to another.

The directions also known as routes can be learned by a router using a routing protocol then the information is passed from router to router along the route of the destination.

IP Address’s

Every machine connected to the internet is assigned an IP address. An example of an IP address would be 192.168.0.1. IP addresses are displayed in decimal format to make it easier for humans to understand but computers communicate in binary form. The four numbers that separate an IP address are called Octets. Each position consists of eight bits. When added to together you get 32 bit address. The purpose of each octet in an IP address is to create classes of IP addresses that can be assigned within a network. There are three main classes that we deal with Class A, B and C. The octets of an IP address are split into two parts Network and Host. In a class A address the first octet is the network portion, this determines which network the computer belongs to, the last octets of the address are the hosts that belong to the network.

Sub netting

Sub netting allows you to create multiple networks within a class A, B or C address. The subnet address is the address used by your LAN. In a Class C network address you would have a subnet mask of 255.255.255.0. A subnet mask identifies which portion is network and which is host. For example 192.168.6.15 the first octet three octets are the Network address and the last octet being the host(Workstation). It is important to subnet a network because gateways need to forward packets to other LANS. By giving each NIC on the gateway an IP address and a Subnet mask it allows the gateways to route packets from LAN to LAN. Once the packet arrives at its destination, the gateway then uses the bits of the subnet portion of the IP address to decide which LAN to send the packets.

Circuit Switched Leased Lines

A circuit switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Here are some terminologies associated with a Circuit switched network.

Frame relay is a telecommunication service designed for cost-efficient data transmission between local area networks (LANs)

Basic rate interference is a service used by small business for internet connectivity. An ISDN BRI provides two 64 Kbps digital channels to the user.

Primary rate interface (PRI) is a telecommunications standard for carrying voice and data transmissions between two locations

All data and voice channels are ISDN and operate at 64kbit/s

Packet Switching

http://www.raduniversity.com/networks/2004/PacketSwitching/main.htm – _Toc80455261

Packet switching refers to protocols in which messages are broken up into small packets before they are sent. Each packet is then transmitted over the Internet. At the destination the packets are reassembled into the original message. Packet switching main difference from Circuit Switching is that that the communication lines are not dedicated to passing messages from the source to the destination. In Packet Switching, different messages can use the same network resources within the same time period.

http://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode

Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and protocolwhich encodes data into small fixed-sized cells.

ISDN is used to carry voice, data, video and images across a telephone network. ISDN stands for integrated services Digital Network. Isdn also provides users with a 128kbps bandwidth. This is done through frame relay. Frame relay complements and provides a service between ISDN, which offers bandwidth at 128 Kbps and Asynchronous Transfer Mode which operates in somewhat similar fashion to frame relay but at speeds from 155.520 Mbps or 622.080 Mbps. Frame relay is based on the older X.25 packet switching technology and is used to transmit analogue signals such as telephone conversations.

PSDN stands for packet switched data network and is a data communication network. Packet switched networks do not establish a physical communication signal like the public telephone does (circuit switched network) Packets are sent on a fixed length basis and assigned with a source and a destination address. The packets then rely on the routers to read the address and route the packets through the network.

Mobile and Broadband Services

Digital Subscriber line(DSL) is mainly used to bring high bandwidth connections to homes and small business’s over a copper wire telephone line. This is can only be achieved if you stay within the range of the telephone exchange. DSL offers download rates of up to 6mbps allowing continuous transmission of video, audio and 3D effects. DSL is set to replace ISDN and compete with the cable modem in providing multimedia to homes. DSL works by connecting your telephone line to the telephone office over copper wires that are twisted together.

Asymmetric Digital Subscribers Line is most commonly used for home users. It provides a high download speed but a lower upload speed. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream.

http://en.wikipedia.org/wiki/Symmetric_Digital_Subscriber_Line

Symmetric Digital Subscriber Line is a digital subcriber line which runs over one pair of copper wires. The main difference between ADSL and SDSL is the difference in upload and download speeds. SDSL allows the same upstream data rate and downstream data rate as ADSL upstream can be very slow.

[http://searchnetworking.techtarget.com/sDefinition/0],,sid7_gci558545,00.html

HDSL High bit-rate Digital Subscriber Line, one of the earliest forms of DSL, is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that provides equal bandwidth in both directions.

IDSL is a system in which data is transmitted at 128 Kbps on a regular copper telephone line from a user to a destination using digital transmission.

The Local Loop enables operators to connect directly to the consumer via copper local loops and then add their own equipment to offer broadband and other services. This process involves operators accessing local exchange buildings to connect to a network of copper lines which connect them to homes and businesses. BT is an Example of a Local Exchange. The local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit.

Benefits of using DSL

DSL can provide virtually instantaneous transmission of voice, data and video over ordinary copper phone lines. A DSL connection can eliminate delays when waiting to download information and graphics from the Internet. It provides users with a cost effective high speed Internet connection. Another benefit is that a DSL connection is always on-line (like a LAN connection) with no waiting time for dialling or connecting.

There are now more than 10 million broadband connections in the UK. By December 2005 there were 9.792 million broadband connections in the UK and the average broadband take up rate during the three months to December was more than 70,000 per week.

Recycling Metal What You Should Know

It seems that everyone is making the effort to recycle these days, but few really understand what materials can be recycled. While we’re all aware of the more common ones like paper and plastics; metal seems to be a tough one to remember. It is true though; you can recycle metal as long as you know what metal items and how to go about it. As a matter of fact, the amount of residential or household metal scrap is incredible! Our homes are filled with metals that can and should be recycled once we no longer have any use for them and these household metals can be divided into several groups: white goods, large household metal scrap and small residential metal scrap.

Recyclable Metal Scrap Categories

White Goods: This term refers to large household appliances and includes things such as refrigerators, stoves, dishwashers, washer and dryers, etc.

Large Household Metal Scrap: This category includes things like patio furniture, aluminum siding, bicycles, window and door frames, barbecues, larger auto parts, etc. Note that microwaves and air-conditioning units can be classified as white good as well.

Small Residential Metal Scrap: Utensils, pots and pans, coat hangers, tools, small auto or bike parts, watering cans, screws, nails, hooks, bolts, pipes and hinges are all a part of this category as well as many other small metal items used for renovations or general household use.

While most items will fit into one of the categories listed above; you may come across items that contain metal that you aren’t quite sure of. These metal-bearing scrap items can also be recycled once they have passed their prime and are no longer needed – a great thing seeing as how our homes are full of these items!

Metal-bearing scrap items include things such as: Extension cords, electrical wires, holiday lights, umbrellas, eye glasses, belt buckles, lamps, handles, computer hardware… the list goes on. This pretty much includes any electrical items that you may have lying around the house as well as most sporting equipment like skates and racquets.

When it comes to recycling these items you should check the regulations with your local government office as some of these items are not able to be left curbside with your other recyclables like glass, papers and plastics. Some municipalities require that you call and make arrangements for pick up while others leave you to make your own arrangements. Luckily there are several options in your local phone directory when it comes to recycling metal scraps-this is a big industry you know! There are several scrap yards that will send a truck to pick up your white goods and such; all you need to do is get them out to the curb for them. There are even places that will pay you for your metal scraps and will happily send someone out to pick up your items if there is enough to make it worth their while. This certainly makes you see spring cleaning in a whole new light, doesn’t it?