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EXPERT SYSTEM

An expert system is a computerised system that attempts to reproduce the decision-making process of an expert human being. Expert system use a knowledge base and a set of rules. 

Building an expert system is known as Knowledge engineering and it is composed of three main components :

Knowledge base

Is a database that allows the storage and retrieval of the knowledge provided by a collection of experts. It contains knowledge about the specific area for which the expert system can be used.

Inference engine

Part of the expert system that makes judgements and reasoning using the knowledge base and user responses. It is designed to produce reasoning based on  a set of rules.

User interface

Is the way the user interacts with the expert system. They are often graphical in nature and have a range of selection processes or typing methods to allow the user to provide responses.

       Expert systems are mostly used for medical diagnosis, car mechanical diagnosis, playing chess, providing financial advice, troubleshooting computer and printer issue, identifying items, and using telephone helpdesk. 

expert system company, check : http://www.expertsystem.com/

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NETWORK

Network is a set of computers and devices connected together so they can communicate and share resources.

A single computer is known as standalone and up until 1990s, computer in homes and organisations were largely stand-alone devices. The way a network is designed is called its architecture. A network architecture can be described by its geographical and physical  nature, by how the data is stored and accessed on it.

Topology – Network topology is the layout of the connections (links, nodes, etc.) of a computer network. There are two main types of topology. Network topologies may be physical or logical. Physical topology means the physical design of a network including the devices, locations and cables.

Network has advantages and disadvantages – networking comps will mostly outweigh the disadvantages

Advantages :

File servers can be used to store data in a central location. Makes it easier to keep the data secure and create back-up copy.

Users can share their data with other users on the network

Communication can be sent from one comp to another

Users can access their data from different computers on the networK

LAN & WAN

Local Area Network

Local area network (LAN)  is a network that covers a small geographical area.  Found at home , schools, unis and small businesses.

Wide Area Network

Wide area network (WAN) is a network that covers a large geographical area ( Example: Banks). More clients and more servers in a WAN. Can be confined in a country or spread across several countries. Banks, police force and hospitals. The internet is a global WAN. Several LANs can be connected to form a WAN. A business that has several different branches can operate their network this way.

LAN and WAN can be compared using several different factors.

LAN and WAN describe geographical architecture of a network and how it is physically structured. They do no describe how data is accessed.

Two architectures for storing and accessing the data is: The client server and the peer-to- peer Data Transfer rates; LAN – Can have up to 1 GB per second, WAN – restricted to less than 200 MB per second

Data transmission errors

LAN – Few errors as data packets are sent by short distance

WAN – Greater chance of error packets are sent over longer distances

Connection Method

LAN – Restricted in a small area. Copper wire, fibre optic cable or radio waves

WAN – Expanded to wider location. Copper wire, optics fibre or microwaves are used. Can often use public telephone network systems, leased lines, transmission towers and satellite communication.

Security

LAN – Comparatively high as security can be easier to implement over smaller number of devices and connections.

WAN – Comparatively low security is difficult to implement across higher number of devices and connections

Ownership

LAN - Owned by individuals and organisations

WAN - Elements of the network often use communication infrastructures owned by others.

CLIENT-SERVER & PEER-TO-PEER NETWORK

Client-server

A client-server network uses a dedicated computer to store data, manage resources and control user access. The computer is known as a server. The server acts as a central point on the network that other computers connect to. A computer that connects to the server to access the data and resources it manages is known as a client. A client server network will usually have at least one server and several clients. A network may have more than one server , each one dedicated to handling a specific function. E.g. one server may handle access whilst another handles data storage. Spreading the load across several servers helps to keep the network running efficiently.

Peer-to-peer

Peer-to-peer has no central server to manage the network. Each computer shares its data and resources with all the others. No computer has control over another. Each computer is known as a peer. Users store data on their own computer. They may allow other users to access their files. They can if they wish keep their files private. Individual peers may provide resources that others do not, e.g. a peer may have a printer attached to it.

ARCHITECTURE : 

ADVANTAGE & DISADVANTAGE :

VIRTUAL PRIVATE NETWORK

Companies or organisations may want to allow users to access a network , often a LAN, from a remote location. They use external resources to create this connection. The external resources will be owned by the owner of the LAN, this makes access to the LAN network much less secure. This can be a concern to the owner of the LAN and the users who want to remotely access it. The issue of security can be overcome by implementing a VPN. Once connected to the VPN, the remote computer then has secure access to the LAN’s resources, just as if it were connected directly to the LAN. Security is implemented through the use of tunnelling protocols and encryption. SSH: Secure shell tunnel protocol uses encryption to securely transmit raw data packets across an unsafe network to make it safe.

INTRANET & EXTRANET

Intranets are privately owned that use Internet technology. E.g. web pages for internal use in an organisation,( organisational info, historical data and news). Email and Instant messaging can also be used for internal communication. Training vids can be streamed and watched by employees.Intranets use client-server architecture often using several servers. A web server hosts the Intranets web pages, while an email server handles email communication. Anther server deals with user accounts. Example of an Intranet is a VLE. (Virtual Learning Environment).

A schools VLE will allow parents to access their child’s marks, attendance and reports. A doctor’s surgery may be able to access a local hospital’s extranet to make appointments for a patient. Access to an Extranet is through an organisations website. A user logs in using an email address and password that will notify the Extranet that the user is an authorised external user.

INTERNET AND WWW

Internet use the Internet protocol suite (TCP/IP) to link devices worldwide.

WWW  is an information space where documents and other web resources are identified by Uniform Resource Locators (URLs), interlinked by hypertext links, and can be accessed via the Internet.

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FILE AND DATA MANAGEMENT

FILE TYPES

When data is saved, they are stored in a file, which different software application save in different ways(types).

Here are some file types :

Text : .txt : Stores plain text without any formatting and is useful for transferring data between application, but any formatting will be lost.

Comma separated value : .CSV : stores structured data as plain text in rows with each columns separated by commas. it is useful for transferring data between databases and spreadsheet or other applications which require data in structured format.

Rich text format : .rtf : stores text-based documents and includes the formatting(rich text).

Microsoft word XML document : .docx : stores m’s word processing in open XML format by saving all objects separately  within a compressed file.

Portable document format : .pdf : used to share read only documents that can be accessed by any PDF reader software. Now commonly used for storing documents in the web as its content can be indexed by search engines.

Open document text : odt : open-source file type for word processor documents and can be opened by open-source word processing software and is not tied to one manufacturer.

Open document spreadsheet : .ods : open-source file type for spreadsheet documents and can be opened by open-source spreadsheet software and is not tied to one manufacturer.

Open document Presentation : .odp : open-source file type of presentation that is used by open-source presentation software and is not tied to one manufacturer.

Hypertext markup language : .html : stores web pages that can be opened by any web browser.

Extensible markup language : .xml : file that uses markup language to define objects and their attributes. Used to transfer data between application and can be rad by simple text editor.

Audio video interleave : .avi : Microsoft’s method of storing video files with very little compression. file sizes are big but no data is lost.

moving pictures experts group(MPEG) layer-4 : .mp4 : audio and video are compressed and videos can be shared across the internet.

Waveform audio file format : .wav : stores audio file as waveform data and enables different sampling rates and bit rates. This is the standard format for audio CDs but does not include compression so files are large.

MPEG layer-3 audio compression : .mp3 : stores audio file ina compressed format approximately 10% the size of .wav files, enabling the audio to be shared across the internet.

Bitmap image : .bmp : Stores imager as uncompressed rarter images, storing each pixel individually. Large files but can be accessed by any software.

Joint photographic experts group : .jpg : stores images as compressed raster images, mostly used by digital cameras and is a common format for web graphic but it uses lossy compression meaning the quality can be lost.

Portable network graphic : .png : compressed raster image and can include background transparency colours making it useful when the images are required on different colour background.

Scalable vector graphic : .svg : stores image as 2D vector graphics. it is a standard format for using vector graphics on the web.

Executable program file : .exe : Stores program object code which enables the program to be executed by the computer.

FILE MANAGEMENT

Knowing your format : 

Proprietary file format are file types that have been developed by software manufacturers solely for use within their software. Open-source file formats are file types that have been developed for the purpose of being used by any proprietary software or open-source software. Generic file format enable data to be transferred between software-won’t include any formatting i.e. CSV or TXT.

Knowing file access :

Indexed sequential access - many years ago, data was often stored on a tape which required records to be written one after another onto the tape, it is also accessed the same, storing the data serially and accessing it serially. Therefore it would take a long time to access a needed file from it because you need to read the whole file from the beginning to get into required data/record.

Direct file access - records are stored in random order with no sequence. When storing a file, a hashing algorithm(calculation) is performed on the key field to determine the the storage address where the record should be stored-and when you need the record, the same calculation is put to search for it.

Hierarchical database management system - was created in 1960s and is not commonly used today. It relies on a tree structure which deals with one-to-many relationship and can only work in one direction.

MANAGEMENT INFORMATION SYSTEMS

A management information system (MIS) provides summary information to managers to enable them to make decisions. This additional software collates data from more than one database and interconnect the data form those databases to produce reports/charts that analyse all the data together- this is called executive information system.

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BRIDGING THE DIGITAL DIVIDE GAP

There are a lot of ways to solve this digital divide and the first can start from you.

Open mindedness and will

Sometimes all it needs is just for you to be open minded and motivated, not only studying and broadening your own knowledge it is also important to spread that positivity and knowledge to teach others. Things like volunteering to tech the elders and kids at public library can be an easy step into bridging the gap.

Government and community

Government and local community have also stepped in into bridging the gap.

http://www.computerweekly.com/news/2240218791/Government-pledges-to-reduce-digital-divide-by-25

https://publicadministration.un.org/egovkb/Portals/egovkb/Documents/un/2012-Survey/Chapter-5-Bridging-the-digital-divide-by-reaching-out-to-vulnerable-populations.pdf

http://www.analysysmason.com/About-Us/News/Insight/Bridging-digital-divide-Jul2013/

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DIGITAL DIVIDE

Digital divide is an economic and social inequality with regards to access, use of or impact of information and communication technologies (ICT). In short, digital divide is a gap between people that have access to any ICT and the one who does not.

Factors which contributes : 

CAUSES 

City and rural areas

Geographic location can have an effect on their access to technology services and one aspect of this geographical location is whether you live in a city or rural area.

Access to internet can differ between city and rural area, although the availability of broadband services is expanding in most countries, it is different between the people that lives in the cities and rural areas.

People that lives in rural area tend to have less access to high-speed broadband, these are caused by the infrastructure that are needed might not be installed as much in rural area than in cities and the cost to to build the required infrastructure would be very expensive. The concentration in rural area is not as much as in the city therefore there are not much potential customer to recuperate the cost of building infrastructure for high-speed access.

It can be also caused by the demographics of each places, for example, in cities houses and building are far closer to each other while in rural area each houses nor villages might be far apart from each other. the strength and speed of coverage will often depend on how close together the network masts are, with those close together providing better coverage at a greater speed and this cannot be attained when the places are far away with each other especially when the building cost is high.

Developed and Underdeveloped countries

Places with greater access to modern technologies are places like USA, Europe and northern part of Asia, and these are mostly consist of developed countries.Areas where access is more restricted are the under developed countries such as Africa, India, and south Asia. These are because countries that are underdeveloped would rather use their finance in more important resources such as health service and do not have the extra money to fund on technology development. 

Socio-economic groups

The rich and the poor digital divide can also occur in more developed countries. More financially stable people might be able to afford access to high-speed internet and high performing technologies than the ones with lower financial income, and these can impact on their level of education and ecommerce, essentially creating a greater digital divide.

High and low performing technologies

Those with higher performing technologies and can afford it may be able to enjoy a better experience than those with lower performing technologies.  They may be able to watch movies, and listen to music with much higher quality than those with lower performing technology, because they have technologies that can handle the high level of bandwith needed for the high quality entertainment.

Cultural, motivation,fear and age

Some people believe that ICT is only for particular people like the young ones, the brainy and the middle class and some also believe that ICT is not an important matter, and tends to think important things are only personal communication, kinship and having strong family values.

These beliefs can also cause loss in motivation to learn about ICT, as the people in their environment think that learning about ICT are only for certain people, it makes them lose interest in actually learning about it. Also lack of time and effort will make the digital divide bigger.

Many people are also not using technologies because they are not confident in their own ability thus making them feel scared of attempting, therefore it is better not to try. Some people are also scared of causing problem as they experiment/learn their way through computer and therefore prefer not to try. It might also be because they are scared that the stories they’ve heard about identity theft, internet scam and fraud might happen to them.

Not only because of lack on motivation, fear and cultural, this digital divide also happens in generation gap, some people that are of older generation did not know about these technologies and therefore don’t know how to use it. They also might have beliefs, fear and lack in motivation like listed above, and these generation gap is making the digital divide bigger.

Do you know the kind of efforts people and government are putting to bridge the gap in digital divide? -next coverage:Bridging the gap of digital divide.

Demographic : a particular section of population.

Economic : relating to a country in terms of their production and consumption of goods and services.

Broadband : a method of faster data transmission that can carry several channels of data at once.

Infrastructure : the physical structure that are needed for a service or operation.

Ecommerce : business that is conducted electronically.

Bandwith : the amount of data that can be transmitted at one time.

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E-SAFETY, AND HEALTH & SAFETY

E-SAFETY

Protecting personal data to avoid online exploitation, bullying and identity theft, it also deals with software issues like malware.

A person should be careful about revealing their personal data, such as their bank details, medical records, their salary, and sometimes sensitive data like their political view.

Some simple measure to improve our e-safety :

Only open recommended websites from trusted source, i.e a teacher,

Use search engine with filter to remove inappropriate content,

Do not open any attachment from senders you do not recognise,

Be very cautious when revealing personal data,

Be cautious of pictures or comment you post or send to people,

Do not become friends on social networking site unless you know the people,

Never arrange a face-to-face meeting with the person you met online,

make sure you set all privacy controls that are available on social media accounts,

Report and block any unwanted users,

Use nickname or pseudonym when using internet for entertainment, i.e. playing games.

Way of keeping yourself safe online when using social network :

Report anyone that posts anything abusive about you online, similarly if you post anything abusive about anybody, you could face criminal proceeding.

Make sure the password you use on social networking site are strong and make sure to change it frequently, as it can be difficult to prove that it wasn't you who did something through your account if someone did get a hold of it, make sure to also log out of any account when you log in at public use PC.

Think twice before posting something online, despite deleting it once you post something, you can’t take it back again.

Revealing personal data can also lead to personality theft. Types of measure people get to collect your personal data :

Phishing

Pharming

Smishing

Vishing

Trojan horse

Worms

Spyware

Malicious Adware

Rootkit

Malicious bots

Ransomware

HEALTH & SAFETY

As well as e-safety, issues that can occur when using a computer system, there are also health and safety issues to be aware of.

Health issue :

RSI (repetitive strain injury)

Carpal tunnel syndrome

Backache and muscle spasm

eyestrain

Deep vein thrombosis

Fatigues

Safety issues :

Fire can occur when computers overheat, therefore you should keep a computer in a cool room. In case of fire, make sure CO2 fire extinguisher is nearby. Make sure that you do not over-plug a plug socket.

Trailing wires can trip a person, make sure wires are secured by cable management which will clip cables together and make then less risky.

Spilt drinks can cause computer to short/die/broken, and when food is trapped near the keyboard it is hard to use the computer (unhygienic), therefore make sure to not eat and drink near a computer or in a computer room.

Electric shock can occur if a user touch an open wire and if liquids are spilt on an electrical devices, make sure to handle the wire carefully and replace old/broken wire straight away, also keep liquids away from electrical devices.

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SENSORS

A sensor is an input device that records data about the surrounding physical environment. The sensor inputs this data into computer system to be processed. Once it has been processed, if necessary, an output can be triggered as a response. find more about monitoring and control.

Motion sensors

A motion sensor detects any movement, it can do this either passively or actively. Passive motion sensor is a passive infrared sensor, detects any presence of infrared energy in surrounding environment. Active motion sensor is microwave sensor, where it emits microwaves and detects the changes in reflection it receives back when bouncing off nearby object.

Pressure sensors

Pressure sensor measure pressure, normally of a liquid or a gas. The measure of pressure is based upon the force it takes to stop a liquid or gas from expanding. Most modern sensor pressure sensor use a principal called piezoresistance where a specific level of pressure is linked to a specific level of charge through a substance and if a change in level of charge i detected then it is interpreted as a change in pressure.

Moisture and humidity sensor

Humidity sensor monitor and measure the humidity that is in the air through measuring both moisture and temperature and percentage of moisture present at certain temperature is expressed as level of humidity. 

Temperature sensors

Temperature sensors monitor and measure the temperature of an environment or object.

Light sensors

Light sensors monitor and measure light.

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SOFTWARE

SYSTEM SOFTWARE

Programs that are designed to maintain or operate the computer system.

Operating system

Operating system manages the hardware within a computer system. Operating system manages hardware by carrying out tasks such as: allocating memory to software, sending data and instructions to output devices, responding to input devices such as when key is pressed, opening and closing files on storage devices, giving each running task a fair share of processor time, sending error messages to application or users, and dealing with user logons and security.

Device driver

Device driver is the software that comes with external hardware and sends customised instruction to that specific component i.e. issuing command such as ‘print’or dealing with graphics display on screen.

Utilities

Utilities are part of system software and are designed to perform functions which maintain the computer system.

Compilers

A compiler translates a program written in a high-level programming language into machine code which a computer can understand.

Interpreter

Interpreters also translate a program written in a high-level programming language into machine code, but it uses a different method. Instead of translating the whole source code at once, it translates one line at a time; which can be inefficient.

Linkers

Linker combine object files together to form a single executable file. Computer program often consist of several parts(modules) of programming code where each modules carries out specified task within the program and a linker compile all those modules together.

APPLICATION SOFTWARE

Programs that are intended for productivity or carry out a task for the user.

Word Processing

word processing is primarily used to process words and carry out tasks such as writing a letter, producing a report producing coursework, creating a menu, mail merging and writing a book.

Spreadsheet

Spreadsheet software is mainly used for performing calculations and modelling. Spreadsheet are often used for financial and statistical information.

Database management system

Database management system (DBMS) are used for viewing and editing data within a database. A DBMS can provide features such as data entry screen, filters and queries, making a form or report, graphs, linking tables(on relational database), etc.

Graphics manipulation software

Graphics manipulation software is designed to manipulate graphics and depending on the software’s complexity, their features vary. The most basic bitmap and graphic manipulation software can include drawing shapes, changing canvas size, resizing image, adding layers, selecting colour, adding text, etc. Type: raster, vector.

Photo editing software

Photo editing software is a specific type of graphics manipulation that is focused on editing photographs.

Video editing software

Video editing software is used to capture a moving images(video) and to enhance raw videos by trimming/clipping it, giving effects and transition also putting in music or removing, adding titles, speeding it up, etc.

Communicating software

Communicating software can cover a range of tasks such as instant messaging, audio conferencing, video conferencing and e-mail.

Web authoring software

Web authoring software is used for creation and editing of websites.

Control and measuring software

Control and measuring software is used for controlling devices that are not part of the computer system. Measuring software is used to measure values in the real world. Measuring software will measure values form sensors and control software will control devices, i.e. lights or motors.

Apps

An app/app is another name for a program. It is a piece of software that ca run on a desktop computer or on a mobile phone.

Applets

An applet is a small program designed to carry out a specific task. An applet cannot run on its own but must be executed form within another piece of software. Applets are known as add-ons.

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Destine-I

That string of destiny, Would it end with a happy ending?

My antagonising heart cry out as I repent severing the rope of fate, now lost in void, the ultimate abuse I receive from myself keeps telling me, Invictus ... was the death of me. Thought I had an unconquerable soul, yet it was just pure decadence thinking that I can be the captain of my fate. Now my life brings me nowhere, to the vacant future, nullifying any possibility of alteration.What will become of me? another question that repeats through the day. Can someone come and save me? yet another request my heart cry out.

 with no other excuse except for being a weak and vulnerable person, my lazy self indulge me in a day full of nothingness.

haaahhhhh.... always sighing, dreaming that I could be like Van Gogh, an aspiring person who wanted to change and actually changed himself while creating beautiful things. Will I ever change? oh how ironic of me, stuck in melancholy without doing anything... pathetic.

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HARDWARE

 Hardware is categorised into input, output and storage devices.

                                                        MAIN

Mother board

Mother board is a printed circuit board (PCB) which connects to the main components of a computer. Motherboard always include main bus that’s used to transfer data between hardware components however, some of the components may be the integral part of the motherboard, i.e. Universal serial bus(USB) ports, network port,integrated graphic cards etc. 

Random access memory (RAM)

Random access memory(RAM) is a memory that is used to store currently active programs and data. The more data that is available to the computer, the more data and programs can be used at the same time. RAM is volatile, meaning the content will be lost when the power is off(one of the reason why the content you are working on might be deleted if you haven’t saved it into secondary storage, RAM is the type of memory that can be read and written to.

Read only memory (ROM)

Read only memory (ROM) is the type of memory that can be read but not written to, ROM is non-volatile, meaning the content will be retained even when there is no power (because ROM is powered by a small long-life battery).

MORE ON MEMORY.

Graphic card

Graphic card is also known as a video card, display adapter, or graphics adapter. It generates signals needed to display the output image from the computer, sometimes graphic card is integrated to computer and does not require a separate card. Graphic performance can be improved as a separate processor can be used for graphics.

Sound card

Sound card generates signals needed to output a sound  from computer to the speaker or set of speakers. Sound card have single output for audio(green socket), a single input for microphone(red socket) and a single input for line level devices(Blue socket). Separate sound card that connects with separate motherboard expansion is necessary for high quality or surround sound-which enable multiple output for front, rear, centre, and sub-woofer speakers.

Hard disk drive

Hard disk drive (HDD) is the most common form of secondary storage for a computer do to its relatively low cost per Mega Byte(MB). Data stored on hard disk is non volatile.

Solid state drive 

Solid state drive (SSD) is another secondary storage drive  and it is also non volatile.

                                                  EXTERNAL

Cloud 

Cloud or storage cloud is a storage space of which the services are hosted over the internet and not in the same physical location as the computer is being used. Data is stored on banks or servers that are accessed remotely. Physical device where data is being stored is owned by the hosting company rather than person or organisation using the data.

Monitor

Monitor is a device which enables the visualisation of computer’s output, monitor connects to the graphic card.

Keyboard

Keyboard is a device that consists of buttons used to input texts or to control part of an interface, some countries have different buttons on keyboards used i.e. China has more buttons due to their alphabets.

Mouse

Mouse is a pointing device used to manipulate computer screen.

Printer

Printer is an output device which produces hard copy (Printout) for computer (usually onto paper), some printer also include scanner (this is what you call MFP or Multi-function peripheral. 

Speaker

Speaker is a device which provide sound output and usually connects with the green socket of sound card.

Camera

Camera captures still and moving images(Video) which can be then stored into computer, camera attached to a computer is called webcam.

Scanner

Scanner is an input device which capture a 2D document in the form of an image.

Optical character reader

Optical character reader (OCR)  is the recognition of printed or written text characters by a computer. This involves photo-scanning of the text character-by-character, analysis of the scanned-in image, and then translation of the character image into character codes, such as ASCII, commonly used in data processing. In OCR processing, the scanned-in image or bitmap is analysed for light and dark areas in order to identify each alphabetic letter or numeric digit. When a character is recognised, it is converted into an ASCII code. Special circuit boards and computer chips designed expressly for OCR are used to speed up the recognition process.

Magnetic ink character reader

Magnetic ink character reader (MICR)  is a technology used to verify the legitimacy or originality of paper documents, especially checks. Special ink, which is sensitive to magnetic fields, is used in the printing of certain characters on the original documents. Information can be encoded in the magnetic characters.

Optical mark reader

Optical mark reader (OMR)  is a method of entering data into a computer system. Optical Mark Readers reads pencil or pen marks made in pre-defined positions on paper forms as responses to questions or tick list prompts. The OMR data entry system contains the information to convert the presence or absence of marks into a computer data file.

Barcode reader

Barcode reader  also called a price scanner or point-of-sale ( POS ) scanner, is a hand-held or stationary input device used to capture and read information contained in a bar code . A barcode reader consists of a scanner , a decoder (either built-in or external), and a cable used to connect the reader with a computer. Because a barcode reader merely captures and translates the barcode into numbers and/or letters, the data must be sent to a computer so that a software application can make sense of the data.

Pen drive

Pen drive  also referred as USB flash drive is a portable device which allows user to transfer data (text, images, videos etc) to and from computer quickly. Users can easily read and write the data on the Pen Drive by plugging it into the USB port on the computer. Pen Drives are quite compact and can fit easily into the pocket; they run without battery and draw power from the USB connection itself. Both Floppy disks and CDs are now being gradually replaced by Pen Drive as a preferred means of data storage. Its because latter offers mass data transfer and storage capability and at a much faster rate.

Portable Hard disk drive

Portable HDD is An external hard drive is a storage device located outside of a computer that is connected through a USB cable or wireless connection. An external hard drive is usually used to store media that a user needs to be portable, for backups, and when the internal drive of the computer is already at its full memory capacity. These devices have a high storage capacity compared to flash drives and are mostly used for backing up numerous computer files or serving as a network drive to store shared content.External hard drives are also known as removable hard drives.

Blu-ray disc drive

Blu-ray disc drive is an optical disc format designed to display high definition video and store large amounts of data.Blu-ray is the successor to DVD. The format's name comes from the fact that a blue laser reads from and writes to the disc rather than the red laser of DVD players. The blue laser has a 405 manometer (nm) wavelength that can focus more tightly than the red lasers used for writable DVD. As a consequence, a Blu-ray disc can store much more data in the same 12 centimetre space.

see also :Magnetic tape, CD and DVD

Memory card

Memory card or flash memory is a storage device mostly used in digital camera.

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UTILITY SOFTWARE

Utility programs are part of the operating system of a computer and are routines which carry out important tasks which are necessary from time to time on the system. They do not produce a pretty picture, or a letter which can be sent to someone so they are not application programs, but the types of job that they do are so important that the system could not run without them. There are many examples of utility software but we shall limit ourselves to just a few:

The surface of a disk can store so much data that the computer cannot handle it all at once so it needs to be split up so that data stored on it can be found again. When it is new, a disk surface is blank so the computer “draws lines” on the surface to split it into small areas. The process is called formatting and it is carried out by a utility program called a disk formatter.

When files are to be stored on a disk they need to be managed. This includes arranging for them to be stored in a certain place, finding files again after they have been stored, moving them around to get them in a sensible order and deleting them when they are not needed any more. All of these actions are carried out by utility programs called file handlers.

A computer system is made up of lots of different sorts of hardware, each piece of which needs instructions about how to work. These programs are called hardware drivers.

Some files are very large. In most files it is possible to find simple ways of reducing the size of the file while keeping all its meaning. This can be very important when files are being sent from one computer to another as the communication is sped up. The programs that reduce the size of files are called file compressors.

When files are being sent from one computer to another it is possible that they may contain a virus which will infect the receiving computer. A virus checker (scanner, killer,..) is a utility program which keeps a constant check on files searching for viruses which it will delete(remove) if it finds any.

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USER INTERFACE

The means of communication between the user and the machine is known as the user interface and consists of both hardware and software. There are different types of interface, which are useful in different situations and for different types of user.

Form based :

If the majority of the input to a system is of a standard type, in other words the computer knows what sort of input to expect, then a typical interface will produce a form on the screen to be filled in. This sort of interface would be used where an operator is inputting information while asking a customer questions over the telephone. The interface;

Prompts the operator to ask all the questions.

Makes the operator input the information in the correct order.

Ensures that the information is input in the correct format by having specific areas to input the data.

Makes the checking of the information easier.

The characteristics of a form based interface are that;

It has specified areas for the data. For example, boxes for input of coded material like the date or the gender of the customer, and areas to be filled in with textual information.

It has a cursor which moves to the next box to be filled in, sometimes the box is highlighted to make it clear to the operator where the data is to be inserted.

Some of the boxes are more important than others and the cursor will not move on until some data has been supplied.

It checks that what has been input is sensible for that box before moving on to the next.

Menu based:

Menu based interfaces are used in situations where the operator tends not to know what the options are that are available. Examples of this would be information systems for tourists or users of a particular service. A list of choices is made available followed by a further set of choices based on the first choice, and so on until the result is obtained.

Imagine a system at a train station in a popular holiday location. The first screen may ask for the general area of interest (accommodation, trips, shopping, entertainment..), once the choice of accommodation has been made the next screen may offer different standards of hotels. The next screen may offer different price bands, and finally a list of all the available properties that match the previous choices. Input is often done using a touch screen because of the location of such systems and because the people who use them are often in no way computer literate, meaning that simple systems are essential.

Graphical:

Graphical interfaces are called GUI (graphical user interface) or WIMP (windows, icons, menus, pointer). The terms describe what the user sees on the screen. There are many different types, but the user would expect to be able to view different applications or files on the screen, this is done by putting each into its own boarded area known as a window.

The user will expect to be able to select options by use of menus of choices and by using small pictures which represent the different options available. Choices are selected by the user by using some sort of pointing device to indicate choice, typically this would be a mouse.

Natural language:

Sometimes referred to as a conversational interface, the computer will ask questions which elicit a response which gives the user the impression that they are talking to the computer. The trick is that the system restricts itself to questions to which the only sensible answers are the ones that it knows. If the user leaves the expected responses, a message is produced; this makes clear that a further attempt is required.

Command line:

Or command based interface is one where the user types a series of commands at the keyboard which tell the computer what their intentions are. The user needs to know what the possible commands are, and also needs to understand the way files are stored on the system. The characteristics of a command based interface are;

The user needs to know what commands are available.

The user needs to understand the commands.

 The user needs to understand the way that material is stored in the computer system.

Because of the above points there are two very important characteristics about a command based interface. First, the system is very much more open than in the other types of interface. Other interfaces restrict the options that the user has available to them. The second characteristic is that command based interfaces can only be used by computer literate people because you not only have to understand the commands and their uses but you also need to understand something about how the computer operates, particular how information is stored.

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OPERATING SYSTEM

Batch Processing:

When computing was still a new science, there were not enough machines to satisfy the demand for processor time from students in universities who wanted great calculations done, firms who wanted their payroll worked out, and many others. The big problem was the „speed mismatch‟ between the user sitting at the keyboard that was very slow, and the machine which was very fast

There are two simple solutions to this problem, one is to buy more machines and the other is to make the machines work more effectively by taking away the slowest part of the system – the human being. This problem gave rise to the development of batch processing.

A batch processing operating system is one that does not allow for interaction between the user and the processor during the execution of the work.

Nowadays, batch processing tends to be used where

There are large amounts of data to be processed,

The data is very similar in nature and…

It requires similar processing,

The computer system has identifiable times when it is not being used, and so has available processor time

The application does not require human intervention. -Typical examples of applications which would be done using batch processing include production of bank statements from customer files, production of gas (electricity, telephone) bills from customer records, the compilation of high level language programs where a number of users want programs compiled

Real-time:

A real-time O.S. is one which can react quickly enough to affect the next input, or process to be carried out. Most real-time systems are based on control of some process in the real world or on information handling. A chemical plant has a reaction vessel where the temperature is critical to the result of the process. The temperature is monitored by a computer which accepts input from a sensor and then makes a decision whether to adjust the heating elements in the vessel. In this example, it would not be sensible for the computer to be running any O.S. that is not real-time because if there was a delay in the decision making process, it might mean that the reaction is corrupted in some way.

Single User:

As the term implies, a single user O.S. is specifically one that is used to control a system which has only one user, and their programs, at any one time.

Multi-tasking:

This is a type of O.S. that allows several applications to be available simultaneously. On a simple single user system you will probably be used to having a number of things running at the same time.

PS: most single user OS is also multitasking and vice versa.

Multi-user:

Again, as the name implies, this type of O.S. services more than one user simultaneously. There are two types of multi-user O.S.:

A network system comprises a number of computers linked together for the purposes of communication and sharing of resources. Normally one of the machines is used to control the rest of the system, this machine is called the server. Networks are important because they allow hardware and software to be shared and also mean that a single copy of the information on a system is needed, and so can be kept up to date relatively easily.

 A time-sharing system has a single (normally powerful) computer which is connected up to a number of terminals. These terminals are not computers as in the case of the network system, but have a very limited amount of processing power. Again, such a system allows communication between users on the system and also allows sharing of hardware and software across the system. At the moment it is difficult to tell the difference between the two types of multi-user system, but be careful because a network system is not really a multi user system as each computer is only being used by one person at a time.

Distributed:

A distributed system is one that allows software and data files to be distributed around a system. An ordinary network will have a server controlling it and the access to the hard drive, which is connected to the server. This speeds up access to the data but means that if data is updated on one part of the system it may not be on others, which means that the different versions of the data need to be compared and amended on a regular basis.

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HARDWARE AND SOFTWARE

A COMPUTER SYSTEM CONSIST OF HARDWARE AND SOFTWARE.

The hardware is the physical part of the system. All computer systems require at least four types of hardware.

An input device is any piece of hardware that allows data to be transmitted to the Computer processor. No computer, however powerful, is of value unless able to be given instruction and carry out those instruction.

An output device is any piece of hardware that allows the computer processor to Convey information, or the results of its processing. There is no point in having a Computer system carrying out processing of any sort unless the results of that Processing can be either reported, or projected.

Storage is any piece of hardware which can store data outside the processor in a form which is suitable for input back into the processor. This is necessary because data must be saved for future use if the processor is switched off and for transfer from one machine to another.

The software of a computer system is the various sets of instructions which tell the System how to do things. These sets of instructions are collected together in workable groups known as programs.

 Operating system software is a set of programs, known as system programs, which control the operation of the computer system. They are responsible for the way that the pieces of hardware communicate with each other and for monitoring the way that the hardware of the system is used.

User interface software is used to provide a method of communication between the person using the system and the system itself. Put very simply it is what you see on the screen when you are using the computer.

Translator software is necessary because the computer uses a language that is difficult for human beings to understand and a computer is not capable of understanding human language. The translator software provides the computer with the equivalent of an English-Spanish dictionary so that it can look up what things mean.

Utilities, or utility programs, are system programs designed to carry out common tasks, for instance the programs that control output to the printer or the storage of data.

Programming languages are used to write sets of instructions that the processor can understand because it has a translator for that language. There are many different programming languages, each of which has been designed to solve a particular type of problem by having commands that are useful for solving the problem.

Common applications software includes word processors, graphics, spreadsheets, and many others.

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CHECKING DATA’S AND INFO’S ACCURACY

Validation : to check whether data matches acceptable rules.

Verification : to verify that the entered data matches with original source.

Types of validation and verification explained.

Proofreading : manually checking entered information. By reading both the original source and entered information side by side, you can check whether information entered is accurate or not; but it will take longer than verification or validation, and you might miss out some readings therefore it is good to proofread more than once.

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CODING, ENCODING AND ENCRYPTING DATA

Coding: is representing data by assigning code to it for classification or identification.

Coding data to be stored into computer is similar with coding data while messaging i.e. LOL=laugh out loud, FYI=For your information, BTW=by the way, etc.

Advantages: data can be presented in small spaces, less storage space is required, data can be input quicker, validation is also quicker, data can be confidential(only people who know the codes can interpret it), and if correct codes are used then data can be input consistently.

Disadvantages: codes might be difficult to interpret, may not be enough codes, similarity in some letters and numbers can be confusing, may be less efficient if person does not know the codes and have to take time looking it up, and misinterpretation of information can cause the information to be lost.

Encoding: storing data in a specific format.

when data is encoded,it is stored in specific format;

Text : text is encoded as a number that is then represented by a binary number. A common encoding method is ASCII (American Standard Code for Information Interchange). visit: HERE or HERE

Images : encoding is also used to store images and is encoded as bitmaps. Images can be encoded into a variety of different file types; JPEG/JPG, GIF, PNG, SVG.

Sound : when sound is encoded, the sample rate, bit depth and bit rate are stored. original analogue turn to digital analogue when sound is recorded and broken down into thousands of sample per second. bit rate is calculated using: Bit rate(kbps)=sample rate(kHz)*bit depth(bits)*number of channels.therefore file-size can be found by File size(bits)=bit rate(kbps)*time(seconds). There are 8 bits in a byte, to measure storage you need to divide file size by eight. 

Video : when video is encoded it needs to store images as well as sound. images is stored in frames, and a standard video would have 24 frame per second(fps) while HD uses 50 to 60 fps.

Although stored, to save space, it still needs to be compressed. There are 2 types of compression:

Lossless compression : reducing the file size to 50% without losing quality.

Lossy compression : reducing the file size by reducing the bit rate/image size/resolution, which means some of the quality is lost.

Advantage :enabling real time streaming of music and video, reducing time taken to download files,enabling more storing into storage media, enabling transparent background in files such as PNG and GIF, data can be manipulated.

Disadvantage : required codex might not be installed therefore file can’t be opened with desired format, not all software is capable of opening different file types, some hardware such as music and video players only play a certain format, quality is lost when using lossy compression, text using ASCII or UNICODE needs to be encoded using correct format or else characters wont be recognised.

Encryption : scrambling data so it cannot be understood without decryption key .

caesar cipher : is a secret way of writing used to convert a message into encrypted message. created by Roman Emperor Julius Caesar so that he could communicate in secret with his generals. Caesar cipher is also known shift cipher because it selects replacement letters by shifting along the alphabet i.e.

Symmetric encryption : where both sender and recipient have the key

Asymmetric encryption : also known as public-key cryptography

Find more of symmetric and asymmetric encryption HERE and HERE.

Hard disk : disk encryption will encrypt every data stored on a disk can also be stored in backup tapes and Universal Serial Bus (USB) flash memory. If the whole medium is is encrypted then anybody trying to access the data will not be able to understand it and it is usually accessed by entering password or finger print.

HTTPS (Hypertext Transfer protocol Secure) : It uses SSL (Secure Socket Layer) or TSL (Transport Layer Security) to encrypt and decrypt pages and information sent and received. A secure web can be spotted by its address beginning with https:// and the S stand for Secure i.e. 

Email : email encryption uses asymmetric encryption, this means recipients of emails must have private key that matches public key used to encrypt the original message. Encrypting email will also encrypt any attachment.

Encryption only scrambles the data so that if it is found, it cannot be understood. It does not stop the data from being intercepted, stolen or lost. However, a strong 256-bit AES encryption is virtually impossible to decrypt.

If you’d like to know more about digital representation such as Hz, bits etc. CHECK  MORE ON REPRESENTATION OF INFORMATION.

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QUALITY OF INFORMATION

Information is of  a good quality if :

It is accurate

It is relevant

It is up to date

With enough level of detail (not too much, not too little)

and must be complete.