3.2.7 Consequences of uses of Computers

The computer misuse act 1990- to protect against unauthorised use of computer systems (called hacking or cracking).  There are three levels of severity:

1.  accessing data/programs that you are unauthorised to
2. access  with an intent to commit or allow other people to commit further offences
3. Unauthorised modification of computer material
   
   
   Regulation of Investigatory powers act 2000 (RIPA)- This act prevent interception of public and private messages that are moving but it does allow governments to intercept message if they have the correct warrant.
   
   
   Copyright designs an patents act 1988- this act protects creative media with copyright protection this then means that you can only copy or use copyright items with the owners permission and must acknowledge them.
   Design right then protect how something looks,patents protect how something works and what it does,trademarks protect the name or logo used by a business.

   
   

   Health and safety regulations 1992- this makes employers look after there staff and provide the proper equipment to use a computer long term without getting injury

   
   

   
   

   DRM-stands for digital rights management and they try to control and limit the use of digital media, limit when you can use digital media E.g. limit number of plays, limit only to play on a specific device , count number of install.

   Proprietary software comes with a license which covers who can use the stuff and how many copys they can make.

   
   

   Code of conduct- this is not a law but varies company to company  and is the rules on how employees can use their work computer.

   
   

   Use of robotic- advantages: they are much more accurate and precise than humans,cant get bored,reduce the risk to human life and if made properly resistant to the elements.

   Disadvantage: they cant learn or cope well when they are outside their mission parameters,at the moment they cant make complicated decisions,they sometimes still need a human operator and are usaly built for very specific objectives.

   
   

   
   

   
   

   
   
   The data protection act 1984 and 1998- there are 8 key point to compile with in this act 
   
   

Logic gates

Logic gates- logic gates are the fundamental elements that are used to create all types of computers, modern day processors are comprised of billions of microscopic gates that allow a computer to do all its functions.They use input and run them through different gates and sequence's to get an outputs,inputs and outputs are always in binary.

Truth table-are quick and clean methods (to prevent confusion) of writing down all the possible out puts for various curcitis or individual gates as each type of gate has its own truth table.

And gate-Have two inputs and only gives a on current (a numerical vale of 1) when there are two on inputs otherwise the outputs will all be off (a numerical value of 0) they look like this:

Not gates-only take one input in and reverse the value,this is then the output here is the truth table and what they look like.

Or gate-take in two inputs and as long as at least on input is 1 the output will always be 1.

Xor gate- exclusive or gates work exactly like or gates, the only difference is if there are two on inputs the output will be 0.

Nand gates-work exactly like and gates but you reverse the and out put so its a counciled down version of a and gate followed by a not gate.

Nor gates- an or gate followed by a not gate simplified.

Boolean algebra- is the algebraic way of representing a truth table and is used to simplify large logic gate diagrams

Input devices- a piece of equipment that is used to input a piece of data or instruction into the computer

Output- equipment that is use to get data outside of the computer for viewing

 Input devices                

Optical mouse- this works by using a laser that is fired at the surface and then reflected back at the optical lenses which determines how far the mouse has moved

Voice recognition-this works by using a microphone to record analogue sound and saves it on sound drivers and turns it into digital and compares it to any function on the computer.

Keyboard-this works by depression of the keys making contact and making a current flow.

Touch sensitive-the screen is slightly electrified and when you put your finger on the screen the tiny electro signals from your finger disturb the flow on the screen allowing the device to follow your finger

Graphics tablet-this work by having 2 plates of glass and when you put pressure on the screen to draw the picture these two plates of glass are pushed together allowing a current to flow .

Camera

Device readers

Smart card reader- the card holds a small chip that when plugged into the card reader provides power to and the reader can then access the data on the chip and send and retrieve data over a secure connection.

Magnetic stripe reader-as the card is passed the reader the reader reads the way the card has been magnetised and converts that into binary and reads how much you card has and changes this to the new value.

Optical readers-this works by shining a laser at the exam sheet and where the answer is crossed out the light is not reflected and the cpu recognises this and marks you according to weather or not you got the right answer.It has to be pre-programed though to know were the right answers are.

Barcode reader-this works by each bar representing a number from 0 to 9 and the reader sends out light and waits for the reflection, the bars don’t reflect the light and the reader builds a image of the barcode up and works out the value according to the different bar sizes. Has to be pre-programed

Optical character reader-this reader is pre-programed to recognise different characters and uses the lack of reflection of light to build up the characters and then auto recognises them and turns them into text on a screen.

Radio frequency identifier reader-this works by tags sending out a small radio signal and if the tag is passed by a receiver the radio signals and sets of a current and sets off an alarm. 

finger print scanner-this works by taking a photo of your finger prints and analyzing the contors of your finger it can also be done with light.

Flatbed scanner-light is used to find where  characters are due to no reflected light then turned ito electrical signal that sets the ink use

CRT-In a cathode ray tube, the "cathode" is a heated. The heated filament is in a vacuum created inside a glass "tube." The "ray" is a stream of electrons that naturally pour off a heated cathode into the vacuum. The  high-speed beam of electrons flies through the vacuum in the tube and hits the flat screen at the other end of the tube. This screen is coated with phosphor, which glows when struck by the beam.

Plasma screen-Ech pixel is controlled by a voltage and when charged gas in the pixel is ionized turning the gas into plasma that gives off UV light that when it hit the phosphorus coated  screed turns into different tones of red green and blue.

LCD-in a LCD screen each pixel is divided into sub-pixel of  filters and when a current is passed through the liquid crystal cells a change in polarization makes light

Primary storage- is data that is lost when computer turned off and can be accessed by the processor

Secondary storage-Is storage keeps permanent copies of data and programs in a way that can be easily accessed by a computer and it can't be directly accessed by the processor

Ink jet printer-scans the image at a very fine level and sprays different amounts of red, green and blue to form an image.

Plotter-same as an ink jet printer but on a much larger scale

Laser printer-uses a laser to scan the image and like a photocopier  were tone on a drum is charged negatively and the paper is passed over the drum the charged toner is attracted to the paper.

Impact printer-is mechanical and hammers a character against the paper which hit a ink strip like a type writer

Speakers-the sound card tells the cpu to send an electrical impulse to the speaker causing a pulse in the cone producing sound.

Bit	Smallest unit (a 0 or a 1)
Byte	8 bits
Kilobyte (kb)	1024 Bytes
Megabyte (MB)	1024x1024 Bytes
Gigabyte (TB)	1024x1024x1024 Bytes billion bytes
Terabyte (TB)	1024x1024x1024x1024 Bytes

Hard disk - secondary magnetic storage that can be up to 2TB and is mainly used for storing programs and data

Floppy disk- - secondary magnetic storage that's out-date but would move files below 1.4MB around

Magnetic tape cartridge-- secondary magnetic storage that is used to back up and archive data because of its massive capacity of 800GB

USB flash drive-secondary solid state storage that replaced the floppy disc and is rapidly increasing in capacity +64GB

Memory card- secondary solid state storage that's used for cameras and it capacity is just like usb's

3.2.1 Fundamentals of Computer Systems key words

Hardware is the physical electronic components of the computer e.g. the mother board and graphics card.

Software is the programs and data that run upon the hardware, there are several types of software:

High level software:

System software-software that performs the tasks needed to operate the hardware, again this software can be broken down into 4 other sub sectors these are operating system(performs the tasks that are needed to drive the hardware and acts as an interface for the hardware); library programs(These are programs that  other programs use to get to other things like to access the internet or use printers) ;utility programs(Programs that normally run in the background and usually helps to analyse, optimise and configure your computer like antivirus ) and finally translator programs.

The three translator programs are: an assembler is used to translate assembly code(slightly easier to work with that machine code but still difficult)  into machine code.

A compiler translate the whole source code and maximises it until object code is produced which can then be run, it's fairly slow but only has to be done once and it needs no other program to run it.

A interpreter analyses high level programming like VB and instead of going through a compiler it follows the program out line by line. This is means that the program runs slowly but can be run straight away but has to be done every time you want to use it unlike a compiler ,its often used for simple adverts on the web.

Application Software-is software that allows the user to do generic tasks like writing a letter or listening to music(this is what most people think of as software) but it can be separated into 3 categories.

General purpose-used for many tasks and fairly diverse examples are word processors and spreadsheets usually bought off the shelf they give the user the same thing to everyone else.

Special purpose-does one task very well but can't do much else like route planning software or internet browsers.

Bespoke applications-this is software that is taylor made for a company and the customer get exactly what they want a good example is air traffic control software, can be made by payed for contractors or in-house programmers. Very expensive.

Generations of programing language:

1st gen- machien code the only code the computer can really understand in binary

2nd gen- assembly code

3rd gen-imperative high level as in VB and Java

4th gen- declarative this is were you basicaly tell what the computer what you want to do and it pretty much works it out

Key words and notes for revision 1

The internet is the whole network of networks that’s sends information along thousands of different global paths to other computers.

The web is a small part of the internet that is comprise of webpages, multimedia, text and things that use HTML as structure and transportation.

The intranet is a miniature internet that is private to a network. That can only be accessed internally like the school network.

The extranet is a part of the intranet that has been published to the public like the schools Jogport.

A router is a specialise computer that knows enough about its local part of the internet to send packets generally to the right direction to get to the wanted location. There are many of these to redirect info at each junction of the internet.

Packets are small amounts of data that were part of a larger data e.g.  a document  that has been downloaded. They are broken down into three parts:  The header-this contains the sender’s and receiver’s ip address and the packet sequence; the payload that contains the broken down information and finally the trailer that checks for errors during the send and receive process. 

The domain name is for the use of people to be an easily remembered instead of the ip address. Composed of a top level domain followed by sub domains (first level, second level etc….) working from right to left.

The ip address   is the computers version of a domain name that is binary; they are 8 bite binary number. Every computer has a unique ip address to stop packets from going to the wrong computer.

Domain name server translates the human domain name to the computers ip addresses to locate .They are scattered all over the internet and are constantly updated.

Isp or internet service provider are people like sky that provide you with an internet connection.

Internet registries are people that check for availability of ip addresses and hand them out.

Internet registrars’ are the people who monitor domain name and the people who you buy the rights to a domain name.

URI stands for uniform resource identifier and is the general term for unique identification

URL stands for uniform resource location and uses the specific location in the website address bar for instance

The client is a computer on a network that is sending the request for the resources off the internet from another computer e.g  your computer asking a website to download a file.

The server is the computer on the network that the client is asking for the resources, it is made up from many small computers to make towers.

TCP/IP is code for Transition Control Protocol over the Internet Protocol and are responsible for together moving info around the internet.TCP breaks down the information and turns it into packets of data and transmits it. The IP is responsible for finding other computers and rerouting it around the internet. The TCP/IP can be broken down into 4 layer and is call the TCP/IP protocol stack. The 4 layer are:

The application layer- this is the specific networking application e.g a web browser.

The Transport Layer - this layer breaks the data into small packets and in the header adds the source and destination ports and the packet sequence

The network layer- this layer adds the source and destination IP address to the headers in the packets

The link layer-this layer adds the MAC address to the packet and puts the data on the cable to the nearest router on the network

Here are some common protocols and their port numbers. (sourced for Mr.Klines' Powerpoint)

h/w

Hypertext Markup Language (HTML) is the main markup language for web pages. HTML elements are the basic building-blocks of webpages.
HTML is written in the form of HTML elements consisting of tags, enclosed in angle brackets (like <html>), within the web page content. HTML tags most commonly come in pairs like <h1> and </h1>, although some tags,  are unpaired as they are self-closing, for example <img>. The first tag in a pair is the start tag, the second tag is the end tag. In between these tags web designers can add text, tags, comments, and other types of text-based content.


The HTML tags that I will need to know for the exam are:

<html></html> Creates an HTML document <body></body> Sets off the visible portion of the document <head></head> Sets off the title and other information that isn't displayed on the Web page itself <title></title> Puts the name of the document in the title bar <a href="URL"></a> Creates a hyperlink <p> Creates a new paragraph <br> Inserts a line break <p align=?> Aligns a paragraph to the left, right, or center <ol></ol> Creates a numbered list <li> Precedes each list item and adds a number <ul></ul> Creates a bulleted list <h1></h1> Creates the largest headline <h6></h6> Creates the smallest headline <img src="name"> Adds an image CSS Cascading Style Sheets (CSS) is a style sheet language used to describe the presentation  look and formatting of a document written in a markup language. Its most common application is to style web pages written in HTML. CSS is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation, including elements such as the layout, colours, and fonts.This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple pages to share formatting, and reduce repetition in the structural content. While the author of a document typically links that document to a CSS style sheet, readers can use a different style sheet, perhaps one on their own computer, to override the one the author has specified. CSS specifies a priority scheme to determine which style rules apply if more than one rule matches against a particular element. In this so-called cascade, priorities or weights are calculated and assigned to rules, so that the results are predictable.The CSS specifications are maintained by the World Wide Web Consortium (W3C). A style rule is made up of three parts, a selector, a property and a value: selector {property : value } useful one are selector {color:blue} this would make that line of text blue selector{font-size12px:} this would make the size of the font the value you have chosen selector{font-family:"Times New Roman", Times, serif;} this choses the type of font there are a number of attributes that can be changed a short list would be: fonts,links,lists,tables,text(colour)and background colours

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