Machine Level Architecture

The 3 box model

This diagram explains the basic principles of the CPU(central processing unit) and was named by John Von Neumann in 1945.)

The 3 box model consists of 4 main parts. The processor, which runs programmes and looks after the components. The processor can contain upt 1 billion logic gates or as few as 1 million. The Main memory, whic is also known as the IAS(Immediate Access Storage) The IAS is made up of

• RAM - (Random Access Memory) is volitile and all memory on it is deleted when ever the computer is turned off.
• ROM - (Read Only Memory) is not volitile and the memory on it is not deleted whenever the computer is turned off.
• I/O - (Inputs/Outputs) everything outside the CPU is known as a peripheral and the I/O controllers allow the cpu to communicate with these devices without the CPU knowing exactly how they work. 
• Procesor - Is the brain of the system and controlls all other parts of the CPU. It can do as many ctions per minute as how many time the clock ticks within it, normally around 5 billion times a second in modern computers.
• Buses - Buses allow diffeerent parts of the CPU to communicate with eachother. They travel along wires on at a time carrying a single bit. Most computers have either 32 or 64 of these wires working simultaneously allowing the computer to transfer 32bits or 64bits of information at a time.

Logic Gates and Truth Tables

There are many types of logic these are the 6 main ones


AND Gate
The AND gate will have an output (c) of 1 if both of the inputs (a,b) are also 1, otherwise the output will equal 0.
This can been shown in a truth table like this.
A     B     Q or C
0      1     0
0      0     0
1      1     1
1      0     0

OR Gate
The OR gate doesn't need both inputs to be 1 like the AND gate, but only needs one to equal 1 for the output to be 1. If both are 1 then the output remains at 1.
The truth table for an OR Gate is.
A     B      QorC
0      1      1
0      0      0
1      1      1
1      0      1


NOT Gate
A NOT Gate only has one input unlike other gates and its function is to change what ever the input is.
This is shown on its truth table
A     Q
0      1
1      0
The reason why there is no B input is because there is only one input(A)

NAND Gate
The NAND is a mixture of the AND Gate and the NOT Gate. It gives opposite outputs of an AND Gate.
A     B     QorC
0      1      1
0      0      1
1      1      0
1      0      1

NOR Gate
The NOR Gate is a mixture of the OR Gate and the NOT Gate. It swaps every input around to receive the opposite outputs of an OR Gate.
A     B     QorC
0      1      0
0      0      1
1      1      0
1      0      1

XOR Gate
The XOR Gate is similar to the OR Gate but is exclusive, meaning that if both inputs are 1 te output is 0. But if 1 input is 0 then the input is 1.
A     B     Q or C
0      1      1
0      0      0
1      1      0
1      0      1

Types of Software

System Software
Operating system
Software used to let the hardware of the computer function properly.

Library Programmes
Software used to remember commonly used functions such as printing and other related protocols.

Utilitry Programmes
Perfoms specialised tasks on the computer such as virus checking and file compressing.

Translator Software
Software used to translate all files and commands into machine code suitable for the computer to execute. They can also convert from machine code back to other languages  so that the user can use it.

Application Software
General Purpose
Software that has no specific use. e.g spreadsheet software or a wordpad.

Special Purpose
Software that only has one use e.g a database for an estate agency

Bespoke Software
Software built for a one-off purpose, they cannot be bought off of the shelf e.g software for a airport air control tower.

Hardware Devices

Mouse
used to move acrross GUI(graphical user interface) It works by a laser detecting the movement of the mouse on the X and Y axis.

Keyboard
Used to enter text onto the computer. An electric current continually sans the keys so when a key is pressed the circuit at that part is broken. This leads to the command of the binary digits for that key being put on the screen.

Bar Code Reader
A device used for reading bar codes. A laser scans the bar code and ot is reflected back into the scanner. The reader then searches through a list of ther barcodes to search for a match. Upon finding a match it finds the item that goes with it.

Scanners
A flatbed scanner reflects light off of the object placed on top of the scanner and a mirror image is produced. A cover is used to remove other light sources. Colour scanners use a variety of lights to scan the colours effeciently.

Magnetic Strip reader
A magnetic strip reader reads the orientation of different magnetic pieces placed inside a plastic strip. The two different orientations gives us the 0 and 1s required to give us a binary number.

ASIMO

In the year 2000, Honda started a robotics programme that aimed to make an accurate representation of a human. Its name was ASIMO(Advanced Step in Innovative MObility). Developed in Japan at the Wako Fundamental Technical Research Center. ASIMOs advanceed programming allows it to do various features effectively. One of these is the ability to run. No other robot can run       

HTML and CSS

<html>
<body>
    <p><strong>Opening Paragraph</strong/></p>
    <p><em>Welcome</em><p/>
    <a href = "http://www.pafc.co.uk/"> click me </a>
    <img src = "Z:\My Pictures\ASIMO1#.jpg" </img>
</body>
</html>

this is an example of HTML using different tags.
Examples of these tage are:
<p> which refer to a new paragraph
<em> refers to emphasis or bolding
These tags refer to the text u see on the page and are closed by beging the tag with a / symbol.
e.g. </p>

For more tags look here
http://jogport.johnofgaunt.wilts.sch.uk/moodle/mod/resource/view.php?id=2267
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CSS on the otherhand aims to make evrything simpler to edit at a later date. So rather than having to change the font size and colour a thousand time just changing it once can do it for the entire document.

You can do this by using a <style type = "css/text"> tag
by placin the <p> tag after it and defining the font sizes and colours etc. your web browser will notice this everytime it sees the <p> tag and applies the correct formating.
custom names can be used for CSS aswell.
When you do this u use the <p class "your CSS name"> "your text" </p>
This lets you have an unlimited number of CSS.