Fetch - Decode - Execute Cycle

The job of the CPU is to execute programs using the cycle. This cycle will start as soon as the computer is switched on.

In order to execute a cycle, the code of the program is from the stage of secondary into the main memory. the CPU's program counter (a register within the CPU that records the current instruction being executed) is set to the location of the memory where the first instruction in the program has been stored, and it is the beginning of the execution. This means that the program is now running.

In a program, each code of machinery instruction takes up a slot in the main memory. Each unique memory address has a slot. 

When a program is being executed. The cycle is performed the CPU, this repeats over and over.










Binary
Binary digits are represented by either a 1 or a 0. 1 bit is the smallest unit of data.

In computing we have different ways of representing data:

1 byte = 8 bits
1 kilobyte = 8000 bits
1 megabyte = 1000 kilobytes
1 gigabyte = 1000 megabyte
1 terabyte = 1000 gigabytes

Hexadecimal
Hexidecimal is a base16 system used to simplify binary. It can be written as 0123456789ABCDEF.
Here is a table showing the denary, hex and binary values.









Dictionary Definition of ASCII-
ASCII (American Standard Code for Information Interchange) is the most common format for text files in computers and on the Internet. In an ASCII file, each alphabetic, numeric, or special character is represented with a 7-bit binary number (a string of seven 0s or 1s). 128 possible characters are defined.


Metadata
Metadata is data about data. It tells you the file type, name, data, file extension, etcetera.

Digital images

Graphics on a screen are made up of tiny blocks called pixels. The more pixels on the screen, the higher the resolution and the better the quality of the picture will be. The higher the image resolution, the more memory is needed to store the graphic.

Image files can be either bitmaps or vectors.

Bitmaps

Bitmap images are widely used on digital cameras, smartphones and online. Common bitmap image file types include JPEG, GIF and PNG. Bitmaps are also known as pixelmaps or raster graphics.

Bitmap images are organised as a grid of coloured squares called pixels (short for 'picture elements'). When zooming in or enlarging a bitmap image, the pixels are stretched and made into larger blocks. This is why bitmap images appear as poor quality when enlarged too much.

Each color of an image is stored as a binary number. In the black-and-white image below, each pixel is either black or white. You need a binary value for each different color. As each pixel is either black or white, this image can be encoded with a value of 0 for white and 1 for black.

Vectors

A vector image uses scalable shapes such as straight lines and curves, using coordinates and geometry to precisely define the parts of the image. It is more efficient than bitmaps at storing large areas of the same colour because it does not need to store every pixel as a bitmap does.

Vector graphics can be scaled without losing resolution. They can be enlarged or reduced in size - but the file size will stay almost exactly the same.