ICS2O-What is Computer and Information Science There is a wide variety of definitions for what a computer is or what it does. Our definition for the computer involves three points: It is an electronic and mechanical device. It operates under the control of instructions stored in its memory. It has the ability to input data, process that data and output useful information.

Why Study Computer Science? Why Study Computer Science? Easy - to be computer and information literate. The ability to understand and articulate your knowledge, skills and values regarding the computer and the information it helps to produce, is essential, to live in, contribute to and thrive in an information based society. Before we can enjoy the visual appeal and functionality of a finely hand-crafted china cabinet, much time and effort has to be put into converting a raw resource (wood) into that useful product. In the same way, a computer is entrusted with finding, analysing, and rendering data into a useful form... this is what we refer to as information! Our challenge as programmers is to bring the machine to life so that it can render data into something that is useful to someone or something.

Computer Basics The computer we defined earlier has two basic components: Hardware: The physical devices that make up a computer system. Software: The ordered, written instructions entered into the computer that allow it to perform a specific task.

A basic computer system has four main components: Input: Any device that allows data to be entered into the computer system. Examples include a keyboard, microphone, joystick, light pen, modem, etc.

Processing: Completed in the "Central Processing Unit", where the raw data entered into the computer is converted into a usable form and then temporarily stored. This is where all the action takes place. The processing or "system" unit contains a motherboard, microprocessor, power supply, primary memory (RAM), expansion ports or "slots", etc.

Storage: Sometimes known as "secondary" or "auxiliary" storage. This is where information can be stored so that it can be retrieved at a later date. Examples include a hard drive, zip drive, floppy disk, USB storage devices, etc.

Output: The form by which the result of the process is displayed. Examples of output devices include a monitor, printer, speakers, modem, etc.

Computer Processing A computer's ability to process data remarkably fast is what separates it from other devices. When we refer to the computer, we normally are referring to the system unit, or "box". The system unit contains both processing and secondary storage devices.

The processing component is divided into two important processing components: the Central Processing Unit (CPU) and Main Memory (RAM).

The Central Processing Unit The functions of the CPU are often performed by one important "chip" known as the microprocessor. The microprocessor contains two important components: Control Unit - Controls the information flow through the CPU and main memory. It is the manager of data flow and the machine cycle. Arithmetic Logic Unit (ALU) - Executes all the computer commands. This is done through a series of mathematical operations, calculations and logic decisions. After each command is executed, it is returned to the control unit for further processing or storage

Main Memory This type of memory is referred to as volatile, meaning that when the computer is shut off, or power is interrupted, any information stored in main memory is lost. To store information in a more permanent fashion, auxiliary storage devices are used. Main memory stores the following:

The Operating System (OS) - manages computer files and devices Applications - software designed for a particular purpose Input or Output - data that is ready for processing or information ready to be stored or displayed Working Memory - data that is waiting for further processing Unused Storage - memory space that has yet to be used