Representing Data

Learning Outcomes

Students should be able to:

• describe the difference between information and data;

• describe how data is stored in the following units:

– bit;

– nibble;

– byte;

– kilobyte;

– megabyte;

– gigabyte;

– terabyte;

• identify the following data types: numeric (integer and real), date/time, character and string;

Data

What does ‘151216’ mean to you? Or ‘85748’? Or ‘AABBCCDD’? They should mean nothing. This is because they are examples of DATA. Data is meaningless. It is raw facts and figures that has no context or meaning. Data is information coded and structured for subsequent processing, generally by a computer system. The resulting codes are meaningless until they are placed in the correct context. The subtle difference between data and information is that information is in context, data is not. Any single value taken by itself from a table is an example of data.

Information

Information is the result of when computers process data. It has a context and therefore a meaning to humans. Sometimes computers will simply organise data into a table, or a graph may be produced. When a table has headings this gives the data a context and thus meaning therefore it becomes information.

Units of Data.mov

Units of Data

Digital data can be classified using the following units of storage.

Bit A single 1 or 0 (Short for Binary Digit)

Nibble 4 bits

Byte 8 bits

Kilobyte 1024 bytes

Megabyte 1024 kilobytes

Gigabyte 1024 Megabytes

Terabyte 1024 Gigabytes

The video to the left explains this concept and also how to do data conversions which does come up occasionally in the exam.

Data Types.mov

Data Types

There are a range of different data-types digital data can be stored as:

Character- This is used to represent a single alphanumeric characters including numbers/letters and symbols. Example initial="J"

String- This is used to represent text through alphanumeric characters including numbers/letters and symbols. For example a name or a postcode

Integer- This is used to represent whole numbers

Real- This is used to represent decimal numbers

Date/Time- This is used to represent dates/times

The video to the left explains this concept and gives a few examples.

POSSIBLE EXAM QUESTIONS

1- Describe the term data (2 Marks)

2- Describe the term information (2 Marks)

3- Explain the difference between data and information (2 Marks)

4- Put the following units of digital data in ascending order: (5 Marks)

nibble bit gigabyte kilobyte byte

5- Put the following units of digital data in descending order: (5 Marks)

bit gigabyte terabyte nibble megabyte

6- Convert 4 gigabytes into megabytes (2 Marks)

7- Convert 2 gigabytes into kilobytes (3 Marks)

8- Identify the most suitable data-type for the following information (5 Marks)

Name:

Age:

Address:

Height in CM:

Initial:

Weight in KG:

KEYWORDS