INFORMATION TECHNOLOGY Information and Data

Introduction Information consists of facts and items of knowledge. It can be anything that has meaning to people. A list of names and addresses The contents of a letter The words of a song A map Data is information in a form that can be processed

Data Types Data type is the term used to describe the kind of data used, e.g. whether it is a number or a letter. A character is one of the symbols which are used to make up data (applies to text but also graphics) A string is a group of characters treated as a unit. Alphanumeric data is made up of letters and numbers. Numeric data consists of numbers only (integer or decimals).

Data Storage The main store, also called the main memory, is a fast access memory store in the central processing unit (CPU). The main store is divided up into equally sized units called locations. Each location has a different address.

Bits and Bytes All data storage in computers is binary A binary digit (or bit) is a 1 or 0 used to represent data. The term is also used for the smallest unit of storage. A byte is a small group of bits treated as a unit. Normally a byte consists of 8 bits. 1 Kb is one Kilobyte or 1024 bytes 1Mb is 1000 Kb or 1048576 bytes

Processing Information Information processing is the organisation, manipulation and distribution of information. When data is collected and processed a series of operations is carried out on it this is known as the data processing cycle Data collection Input Process Output

Information processing systems A system is a set of components which works as a unit, this includes the hardware involved, the software, the people and the methods used. Hardware is the term used to describe all the actual pieces of equipment in an information processing system. Software is a general term for programs which are written to help computer users.

Real time processing A real time system is one which processes data without significant delay The computer is always ready for data to be input, results are output straight away Because the output can be produced very quickly it is often used in control applications. The computer is often dedicated to the real time application. It just runs the same program all of the time.

Interactive computing An interactive system is one where use of computer takes place as a conversation between the user and the computer, such as using a PC via a keyboard and screen. A standalone computer is one that is not connected to any other computers. A computer network is a system of computers and workstations which are linked. A computer terminal is a means of communicating with a server.

Batch processing A batch processing system is one where programs and data are collected together in a batch before processing starts. Each piece of work for a batch processing system is called a job. A job queue is a number of jobs stored while the wait to be processed. Examples: Gas board bills, weekly payroll run There is no need for anyone to be present while the job is run.

Multiprogramming Multiprogramming is a method of running several different programs in a computer apparently at the same time. Usually applied to a mainframe running several programs for different people. Multitasking is a method of running several different tasks in a computer apparently at the same time. Usually applied to a PC carrying out several tasks for one person.

Homework 1. A pelican crossing has input, processing and output. Describe each of the following: Bleeper, Button, Red light. 2. Write down 2 items of computer hardware 3. Draw and label a diagram of a computer system which allows you to print out your work. 4. Many supermarkets now use computerized systems. Explain why such a system would be unlikely to be used in a small greengrocer’s shop