A Computer

A computer is a machine which manipulates data according to a list of instructions which makes it an ideal example of a data processing system. Computers take numerous physical forms. The first devices that resemble modern computers date to the mid-20^th century (around 1940—1941), although the computer concept and various machines similar to computers existed prior. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers. Modern computers are based on comparatively tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space. Today, simple computers may be made small enough to fit into a wrist watch and be powered from a watch battery. Personal computers in various forms are icons of the information age and are what most people think of as "a computer". However, the most common form of computer in use today is by far the embedded computer. Embedded computers are small, simple devices that are often used to control other devices—for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children’s toys.

The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. Any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.

These components are found in virtually every computer:

• Processor: The 'brain' of the computer. It executes instructions sequentially and processes data. The processor is usually divided up into the Arithmetic and Logic Unit (ALU), and the Control Unit. The ALU carries out logical evaluations (for example comparisons), and mathematical expressions (such as addition and subtraction). The Control Unit carries out the functions that organize instructions and co-ordinates all the data and instructions, similar to traffic lights controlling the flow of cars. The processor is also called a Central Processing Unit (CPU).
• Clock: A piece of hardware used to keep the processor (and some other integrated circuits) in time by oscillating at a steady frequency.
• Main Memory: This is temporary storage that stores data currently being worked on. It is accessible to the processor directly, without going through any input/output channels. It does, however, need to connect to the processor via the data, address, and control buses. When power is lost, all data stored in main memory is lost, therefore meaning it is volatile. Main memory is also known as Immediate Access Storage (IAS).
• Address Bus: A collection of wires between the processor and main memory used to communicate the physical location (address) of data in main memory.
• Data Bus: A collection of wires between the processor and all internal devices, and is used to send and receive both data and instructions.
• Control Bus: A collection of wires between the processor and devices used to send commands and get status signals from the devices. For example, it could show whether the computer was reading or writing to memory.
• I/O Port: An interface and physical connector that allows peripherals, such as a keyboard, mouse or monitor, to communicate with the 'heart' of the computer system — the processor and main memory. I/O stands for Input/Output.
• Secondary Storage: This is computer memory that is not directly accessible to the processor but uses the I/O channels. It is for storing data not in active use and preserves data even without power, meaning it is non-volatile.

7. Fill in the blanks using the following words:stored;processor; memory; storage; embedded; devices; to perform; computer; consumed; processing; processes

1. We may call computer a data … system. 2. The first … resembling computers appeared around 1940—1941. 3. Early computers … much power. 4. The … computer is the most common form of computer in use today. 5. Computers are able … the same tasks. 6. … is the heart of the computer system. 7. Processor executes instructions and … data. 8. Main … is accessible to processor directly. 9. When power is lost, all data … in main memory is lost. 10. Secondary … preserves data even without power. 11. … has changed the lives of many people.

8. Answer the questions on the text of exercise 6:

1. What is a computer?

2. When do first devices resembling computers appear?

3. What was the size of early computers?

4. What can you say about the size of modern computers?

5. Did early computers consume much power or not?

6. Are computers important in our world?

7. What can you say about the use of embedded computers?

8. What parts of computer do you know?

9. Which part is considered to be the “brain” or the “heart” of a computer?

9. Fit given definitions with appropriate terms:

Terms

Definitions

A Secondary storage B Hardware C Computer D Processor E Program F Printer G Peripherals   H Software

A machine which manipulates data according to the list of instructions. A list of instructions. Equipment connected to a processor: monitor, keyboard, mouse, printer, scanner, etc. Parts of computer which do not have material form: programs; data; protocols, etc. We call it the “brain” of the computer” Parts of computer system in physical form. It stores data not in active use and preserves data even without power. Device which prints the documents.

10. Read the text:

Дата добавления: 2015-09-04