A computer is an electronic machine that accepts data in a certain form, processes the data, stores and gives the results of the processing in a specified format as information (manipulates data according to a set of instructions).
What distinguishes a computer from other information-processing devices are three basic characteristics:
- A computer is completely electronic- all its functions are carried out with electrical signals.
- A computer can remember information and hold it for future use. Computers do this on a temporary basis with memory circuits and permanently with storage devices such as magnetic disk and tape.
- A computer is programmable. Unlike other devices, built to perform a single function or limited range of functions, a computer can be instructed to do whatever task we tell it to do.
A typical computer consists of two parts: hardware and software.
Hardwareis any piece of computer equipment, electronic or mechanical parts making up the computer system that are tangible objects.
Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called "firmware" to indicate that it falls into an uncertain area somewhere between hardware and software.
There are three basic hardware sections.
1. The CPU is the most important item of hardware, the heart of the computer, a microprocessor chip at the center of the computer system which processes data, executing program instructions, and coordinates the activities of all the other units.
2. The main memory holds the instructions and data which are being processed by the processor. It has two main sections: RAM (random access memory) and ROM (read only memory).It only stores information while the computer is switched on and it has a limited capacity.
3.Peripheralsare the physical units (devices) that can be attached to the computer. They include:
- Input devices, which enable data and commands to be fed into the computer memory (e.g. the keyboard and the mouse).
- Output devices, which let us extract the results from the system, usually to display the processed data (e.g. the monitor and the printer).
I/O is the means by which a computer exchanges information with the outside world. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.
- Storage devices, which are used to store both data and programs permanently (e.g. hard disks and DVD-RW drives). They have a much greater capacity than the main memory. Disk drives are used to read and write data on disks.
On the rear panel of the computer there are several ports into which we can plug a wide range of external devices with the help of connectors (e.g. a scanner, a modem, etc.). They allow communication between the computer and the devices.
These are the main physical units of a computer system, generally known as the configuration.
CONTENTS | KEY INFORMATION SECTION 1 | Types of computer systems | VOCABULARY PRACTICE SECTION 3 | GRAMMAR PRACTICE SECTION | READING PRACTICE SECTION | SPEAKING/WRITING PRACTICE SECTION | FUN AND GAMES SECTION | KEY INFORMATION SECTION 1 | VOCABULARY PRACTICE SECTION 1 |