Computer Fundamentals

Introduction to Computers

A computer is a man-made, programmable electronic machine that can store, retrieve, and process data according to a given set of instructions. whatever information given to a computer is termed input.

 The computer input typically comprises two things: Data and Instructions. The data are the facts, which are to be processed, and the instructions describe how the computer should process the data. the data which has been converted or organized into a more useful or ineligible form for direct utilization or help human beings in their decision-making process is typically termed information.

The heart of the computer is a microprocessor chip. Today microprocessors are embedded inside various everyday machines such as cars, television sets, and washing machines. these microprocessors usually control some function of the machine and are hidden from the users. the term computer can virtually be applied to any such device that has a microprocessor in it. 

However, most people describe a computer as a device that comprises a keyboard, mouse, a central processing device, and a screen. 

Overview of the Personal Computer

Characteristics of Computers

The main characteristics of computers are:

• Speed

A computer can perform tasks very fast. for example, the amount of work that a human being can do in an entire year - if he worked at and night and did nothing else, can be accomplished by a computer within few minutes.

• Accuracy

The accuracy of a computer is consistently high and the degree of accuracy of a particular computer device upon its design. Errors can occur in a computer. but these are mainly due to human mistakes.

• Diligence

Unlike humans begins, a computer is free from monotony, tiredness, lack of concentration, etc.., hence a computer can work for hours without making any errors or complaints. even if ten million calculations have to be performed, a computer will perform the ten-millionth calculations with exactly the same accuracy and speed as the first one.

• Versatility

A computer is capable of performing almost any task provided that the task can be reduced to series of logical steps. (i.e. a computer program).

• Power of Remembering

Every piece of information that a user 'stores' on a computer can be retained as long as is needed and can be recalled when necessary. Even after several years, the information recalled would be identical to what was fed to the computer. A computer will never lose stored information on its own; a user has to 'remove' (or delete) the information from it. 

•   No I.Q

A computer can only perform tasks that a human being can. The difference is that performs these tasks with unmatchable speed and accuracy. It possesses no intelligence of its own. Its I.Q. is zero, at least till today. It has no be told what to do. hence, only the user can determine what tasks a computer will perform. 

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Components of Computer System

By considering the functions performed by the various components, a computer can be represented as a collection of logical components. The main hardware components of a modern computer system are the central processing unit (CPU), the main memory, the secondary storage, and the input-output devices.

Block Diagram for Computer System

System Unit

The system unit or the cabinet houses most of the essential components of the computer system such as the power supply, the motherboard, the CPU chip, specialized chips, the system clock. RAM, ROM, expansion boards, and bus lines.

Central Processing Unit(CPU)

The central processing unit performs the majority of calculations and controls the operation of a computer. CPUs are rated by the speed at which they can execute instructions. the speed of the CPU is measured in Megahertz (MHz) and is also known as the clock speed. 

The higher the value of the speed the faster computer can run programs. The capacity of a CPU is expressed in terms of word size. A word is the maximum number of bits that the CPU can manipulate or store at one time.

Different manufactures are making CPUs today. Some of these popular CPUs available today are Intel, AMD, Cyrix, and Motorola. 

The CPU consists of two parts: 

•  Control unit(CU) 

•  Arithmetic/logic unit(ALC).

Control Unit(CU)

The control unit controls and directs the operation of the entire computer system. Although it does not perform any actual processing on the data, the control unit acts as a central nervous system for the other components of the computer. It obtains instructions from the program stored in the main memory, interprets the instructions, and issues signals, which cause other units in the system to execute them.

Arithmatic-Logic Unit(ALU)

The  Arithmetic-Logic unit performs arithmetic operations such as addition, subtraction, multiplication, and division on data.

In microcomputers, the entire CPU is typically fabricated on a single chip.

MotherBoard

The Motherboard is the main circuit board inside the computer. It can be considered as the main communication center through which all the components of the computer transmit data back and forth. All the main parts including the CPU of the computer are typically plugged into the motherboard.

 The motherboard also provides sockets, called expansion slots, to plug in special electronic circuit boards to enhance the functionality of the computer. these extra circuit boards are called expansion cards, by using which you can customize a computer to suit your needs. One other major function of the motherboard is to supply the necessary power to all its expansion cards.

System Clock

Computers run to the beat of a clock. A clock in the computer that tricks one million times per second is called one megahertz (1MHz) clock. Generally, a faster clock means faster execution of programs, hence better performance. However, the actual performance of a computer depends on many other factors.

Power Supply

The regulated power supply inside the computer transforms mains electricity into DC current used in the computer. It has an internal fan to cool the unit.