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 • Informationprocessing 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