A computer is an electromechanical device that takes raw data as input, processes the raw data with control of set of instructions and gives the desired result. It can process both arithmetic and logical calculations.

The physical parts that make up a computer i.e. central processing unit, input, output, and memory are called hardware. Set of Programs are called software. Peripherals are any hardware device connected to a computer, any part of the computer outside the CPU and working memory. For ex. keyboards, the mouse, monitors, printers, scanners, disk and tape drives, microphones, speakers, joysticks, plotters, and cameras.

Evolution of Computer Technology

• The origin took place in the 19th century.
• The ABACUS, the first computer in the world, was used to perform simple calculations
• In the 17th century, a scientist named Pascal developed Pascaline to perform mathematical calculations.
• This machine is comprised of a number of gears.
• Charles Babbage wrote on the use of logic and loops in process execution. On the basis of which he envisaged Analytical Engine and Difference Engine.
• George Boolean developed the famous Boolean algebra based on binary numbers.
• De Morgan put forward De Morgan’s Theorems theorem on logic gates.
• Lady Ada was the first computer programmer.
• The real application of computers began in the late fifties.

Advantages of Computer

• High accuracy
• Speed
• Large storage capacity
• Graphical User Interface
• Portability
• Platform independent
• Economical

Generations of Computers

First Generation

• Bulky in size.
• Able to execute hundreds of instructions per second
• Expensive
• Used vacuum tubes as their main components.
• Machine language was used
• Example EDVAC, UNIVAC, etc.

Second Generation

• Smaller in size than first-generation computers
• Capable of executing thousands of instructions per second
• Transistors were used
• Assembly language was used
• Example, PDP (Programmed data processor), PDP1, etc.

Third Generation

• More advanced
• Used Integrated Circuits
• Contained thousands of components per circuit
• Cheaper than second-generation computers
• Languages used were BASIC, COBOL, etc.
• Example IBM 307 Series, PDP II, etc.

Fourth Generation

• Used large scale integrated circuits called microprocessors or chips
• Less costly as compared to the third generation computers
• Able to execute millions of instructions per second
• Languages used in this generation are C++, SQL, etc.
• Example CRAY 2, IBM 3090/600 Series

Fifth Generation

• Work on artificial languages (AI) like LISP, PROLOG, etc.
• Use super/ultra-large-scale integrated circuits
• Execute billions of instructions per second
• Examples, Laptops, Palmtops, PDA (Personal Digital Assistant), etc.

Types of Computers

Analog Computers

• Processes Analog Signals which are continuous signals; example: the sine wave.
• Analog quantities are based on decimal number systems; examples: slide rule, ABACUS, etc.

Digital Computers

• Process digital signals which are discrete signals with two states 0 and 1.

Batch Processing

• The computer acts as a ‘stand-alone’ unit
• Available for a single user
• Number of programs can be executed simultaneously
• They have to stand in queue