Reading. A computer is an electronic machine that accepts, processes, stores and outputs information

A computer is an electronic machine that accepts, processes, stores and outputs information. A typical computer consists of two parts: hardware and software. Hardwar e is any electronic or mechanical part of the computer system that you can see or touch. Software is a set of instructions, called a program, which tells a computer what to do.

There are three basic hardware sections.

1. The CPU (central processing unit) is the heart of a computer, a microprocessor chip which processes data and coordinates the activities of all the other units. Its speed is measured in megahertz (MHz) or gigahertz (GHz). The higher the speed of the CPU, the faster the computer will run.

2. The main memory has three sections: RAM (R andom A ccess M emory) stores the data being processed, ROM (R ead O nly M emory) stores the program instructions the computer needs to start up, and cache memory speeds up the processing. The RAM memory is measured in megabytes (MB).

3. Peripherals are the physical units attached to the computer. They include:

Input devices which let us enter data and commands (e.g. the keyboard and the mouse)

Output devices which let us extract the results of the processing (e.g. the monitor and the printer)

Storage devices are used to store information (e.g. hard disks drive and CD-ROM or DVD drive). Disk drives are used to read and write data on disks. The hard disk stores data and software programs. Its size is measured in gigabytes (GB).

The main parts of a desktop computer are enclosed in a box known as the system unit. It contains an electronic board called motherboard that holds and connects together the main electronic components. The motherboard usually has empty electronic connectors, called expansion slots, into which additional electronic boards (sometimes called expansion cards) can be plugged. This allows extra electronic components to be added. For example, more memory can be added by plugging memory boards into the memory slots. Sound facilities can be added by plugging a sound card into an expansion slot. The system unit usually also contains a small speaker (or loudspeaker), the power supply, and storage devices. Some other devices may be included in the system unit but most input and output devices are plugged into the back of the system unit using connectors known as ports.

Power is a function of both speed and capacity. The power of a computer depends on the combination of all the components. When buying a computer, you can often choose between different components. For example, you can choose between different processor speeds, amounts of memory, and hard disk sizes.

Task 1. Read the text and find:

a. The definition of a computer

b. The function of the CPU

c. The function of cache memory

d. How to add more memory to a computer

e. Criteria of the computer’s power

Task 2. Find in the text computer components by their definition:

a A common cursor control input device used with a graphical user interface.

b It’s part of the memory store. It has extremely fast access. It can speed up the computer.

c These let you add features such as sound or modem to your computer.

d This kind of memory contains all the instructions your computer needs to activate itself when you switch on. Its contents are retained when you switch off.

e The main electronic input device that has keys arranged in a layout similar to a typewriter.