# A-level Computing 2009/AQA/Computer Systems, Programming and Network Concepts/Introduction to Information and Data Representation
## What is Data and Information?

You may have used the words data and information to mean the same thing in everyday conversation, but it is very important that you know the difference between the two when it comes to computers. Roughly speaking data is the raw stream of 1s and 0s inside the computer and information is when the computer makes sense of this stream. It is interpretation of data in computers and different ways of storing information, that we shall now cover.
   Consider data as an encoded form of information and information as any form of communication that provides understandable and useful knowledge to the recipient. - AQA

## Data

"Data consists of the raw facts and figures that a computer will process into useful information"

### Sources of Data

Data can come from a wide variety of areas, but a good way to think about it is data comes from anywhere where there is an input into a computer. This may be from a keyboard, a scanner, a microphone or a disk drive, amongst many others.

### Direct and Indirect Data

Data may be collected with a desired purpose in mind, for example collecting data from a weather station. This kind of data collection is called direct data collection. Other times data may become useful for reasons that it was not originally collected for. This is called indirect data collection. An example of this could be, "The data collected above is used to record where a particular video is" this would be an example of direct data and example of indirect data would be "The data collected is used to build up a profile of the members for targeted advertising".

### Information

Information is processed data with a structure and meaning
| Denary | Binary | BCD | ASCII |
| 0 | 00000000 | 0000 | 0100 0000 |
| 1 | 00000001 | 0001 | 0100 0001 |
| 2 | 00000010 | 0010 | 0100 0010 |
| 3 | 00000011 | 0011 | 0100 0011 |
| 4 | 00000100 | 0100 | 0100 0100 |
| 5 | 00000101 | 0101 | 0100 0101 |
| 6 | 00000110 | 0110 | 0100 0110 |
| 7 | 00000111 | 0111 | 0100 0111 |
| 8 | 00001000 | 1000 | 0100 1000 |
| 9 | 00001001 | 1001 | 0100 1001 |
| 10 | 00001010 | 0001 0000 | 0100 0001 0100 0000 |
| 11 | 00001011 | 0001 0001 | 0100 0001 0100 0001 |
| 12 | 00001100 | 0001 0010 | 0100 0001 0100 0010 |
Consider data as an encoded form of information and information as any form of communication that provides understandable and useful knowledge to the recipient.

## Number Representation Systems
### Binary number system

Describe the representation of unsigned decimal integers in binary. Perform conversion from decimal to binary and vice-versa. Pure binary representation of decimal integers

### Binary-coded decimal (BCD) representation

Describe the representation of unsigned decimal integers in binary-coded decimal. Perform conversions from decimal to BCD and vice versa. Explain advantages of BCD.

## Information Coding Schemes
### ASCII EBCDIC Unicode

Describe standard coding systems for coding information expressed in character form and other text-based forms. Differentiate between the character code representation of a decimal integer and its pure binary representation.