⏫BINARY AND DENARY⏫
Binary describes a numbering scheme in which there are only two possible values for each digit: 0 and 1.
Bit(short for binary digit) is the smallest unit of data on a computer; each bit has a single value of either 1 or 0. executable (ready-to-run) programs are often identified as binary files and given a file name extension of ".bin.” Programmers often call executable files binaries.
| B I N A R Y T O D E N A R Y |
In everyday life, we use numbers based on combinations of the digits between 0 and 9. This counting system is known as decimal,denary or base 10.
⏫BITS AND BYTES⏫
Bits can be grouped together to make them easier to work with. A group of 8 bits is called a byte.
Other groupings include:
- Nibble - 4 bits (half a byte)
- Byte - 8 bits
- Kilobyte (KB) - 1024 bytes (or 1024 x 8 bits)
- Megabyte (MB) - 1024 kilobytes (or 1048576 bytes)
- Gigabyte (GB) - 1024 megabytes
- Terabyte (TB) - 1024 gigabytes
Most computers can process millions of bits every second. A hard drive's storage capacity is measured in gigabytes or terabytes. RAM is often measured in megabytes or gigabytes.
⏫HEXIDECIMAL⏫
In mathematics and computing, hexadecimal (also base 16, or hex) is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or alternatively a, b, c, d, e, f) to represent values ten to fifteen.
⏫ASCII CODE⏫
Pronounced ask-ee, ASCII is a code for representing English characters as numbers, with each letter assigned a number from 0 to 127. For example, the ASCII code for uppercase M is 77. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.
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.
⏫IMAGES⏫
⏫HEXIDECIMAL⏫
In mathematics and computing, hexadecimal (also base 16, or hex) is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or alternatively a, b, c, d, e, f) to represent values ten to fifteen.
⏫ASCII CODE⏫
Pronounced ask-ee, ASCII is a code for representing English characters as numbers, with each letter assigned a number from 0 to 127. For example, the ASCII code for uppercase M is 77. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.
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.
⏫IMAGES⏫
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 pixel maps 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 colour 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 colour. 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.
One of the most common vector file formats is scalable vector graphics (SVG). SVG is an open standard for vector graphics.
It is possible to edit SVG images using numbers to change the size and colour variables in HTML. This is often used for graphs and inforgraphixc in HTML5.
Vector graphics are used in:
- CAD packages
- AutoShapes in Microsoft Office
- animated movies
- encapsulated postscript (EPS)
- animation programmes such as Blender and Adobe After Effects
- image manipulation programmes such as Adobe Photoshop and GIMP
- Adobe portable document format (PDF)
- Windows meta-file (WMF)
Image display
When a monitor or a printer displays a vector image it is rasterised - converted into a grid of pixels. Regardless of the file type, an image will always be outputted onto a screen or printed in pixels.
⏫SOUND SAMPLE RATE AND AUDIO CODEC⏫
Digital audio
Sounds created on a computer exist as digital information encoded as audio files.
Sound input through a microphone is converted to digital for storage and manipulation
Digital sound is broken down into thousands of samples per second. Each sound sample is stored as binary data.
Digital audio quality
Factors that affect the quality of digital audio include:
- sample rate - the number of audio samples captured every second
- bit depth - the number of bits available for each clip
- bit rate - the number of bits used per second of audio
An audio codec is a device or computer program capable of coding or decoding a digital data stream of audio. In software, an audio codec is a computer program implementing an algorithm that compresses and decompresses digital audio data according to a given audio file or streaming media audio coding format.
⏫FECYCLE AND CPU⏫
What is the purpose of the CPU?
The purpose of the CPU is to process data. The CPU is where processes such as calculating, sorting and searching take place. Whatever is done on our computers, such as checking emails, playing games and doing homework, the CPU has processed the data we use.
The CPU is made up of three main components, the control unit, the immediate access store and the arithmetic and logic unit.
The control unit
The control unit controls the flow of data within the system.
The control unit controls and monitors communications between the hardware attached to the computer. It controls the input and outputof data, checks that signals have been delivered successfully, and makes sure that data goes to the correct place at the correct time.
Immediate access store
The immediate access store is where the CPU holds all the data and programs that it is currently using. You can think of it like the numbers typed into a calculator – they are being stored inside the calculator while it processes the calculations. The immediate access store is often referred to as the registers in the CPU.
Arithmetic and logic unit
The arithmetic and logic unit (ALU) is where the CPU performs the arithmetic and logic operations. Every task that your computer carries out is completed here. Even typing into a word processor involves adding binary digits to the file, and then calculating which pixels on the screen should change so that you can see the characters. The ALU’s operations fall into two parts:
- the arithmetic part, which deals with calculations, eg 1 + 2 = 3
- the logic part, which deals with any logical comparisons, eg 2>1
