First computing device

Charles Babbage an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the “father of the computer”.

Analog computers

In 1938  the United States Navy had developed an electromechanical analog computer

Vacuum tubes and digital electronic circuits

In 1934 went into operation five years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes.

Modern computers

The principle of the modern computer was proposed by Alan Turing in 1936.  


The concept of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925

Their first transistorized computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955.

Integrated circuits

The idea of an integrated circuit was conceived by Geoffrey Dummer (1909–2002).

Mobile computers

The first mobile computers were heavy and ran from mains power. The 50lb IBM 5100 was an early example.

Classification Of Computer

Computers can be classified in a number of different ways, including:

By architecture

  • Analog computer
  • Digital computer
  • Hybrid computer
  • Harvard architecture
  • Von Neumann architecture
  • Reduced instruction set computer

By size and form-factor

  • Mainframe computer
  • Supercomputer
  • Minicomputer
  • Microcomputer
  • Workstation
  • Personal computer
  • Laptop
  • Tablet computer
  • Smartphone
  • Single-board computer



First generation (mechanical/electromechanical) Calculators Pascal’s calculator, Arithmometer, Difference engine, Quevedo’s analytical machines
Programmable devices Jacquard loom, Analytical engine, IBM ASCC/Harvard Mark I, Harvard Mark II, IBM SSEC, Z1, Z2, Z3
Second generation (vacuum tubes) Calculators Atanasoff–Berry Computer, IBM 604, UNIVAC 60, UNIVAC 120
Programmable devices Colossus, ENIAC, Manchester Baby, EDSAC, Manchester Mark 1, Ferranti Pegasus, Ferranti Mercury, CSIRAC, EDVAC, UNIVAC I, IBM 701, IBM 702, IBM 650, Z22
Third generation (discrete transistors and SSI, MSI, LSI integrated circuits) Mainframes IBM 7090, IBM 7080, IBM System/360, BUNCH
Minicomputer HP 2116A, IBM System/32, IBM System/36, LINC, PDP-8, PDP-11
Desktop Computer Programma 101, HP 9100
Fourth generation (VLSI integrated circuits) Minicomputer VAX, IBM System i
4-bit microcomputer Intel 4004, Intel 4040
8-bit microcomputer Intel 8008, Intel 8080, Motorola 6800, Motorola 6809, MOS Technology 6502, Zilog Z80
16-bit microcomputer Intel 8088, Zilog Z8000, WDC 65816/65802
32-bit microcomputer Intel 80386, Pentium, Motorola 68000, ARM
64-bit microcomputer[92] Alpha, MIPS, PA-RISC, PowerPC, SPARC, x86-64, ARMv8-A
Embedded computer Intel 8048, Intel 8051
Personal computer Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet PC, Wearable computer
Theoretical/experimental Quantum computer, Chemical computer, DNA computing, Optical computer, Spintronics-based computer, Wetware/Organic computer  


Input devices

When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of input devices are:

  • Computer keyboard
  • Digital camera
  • Digital video
  • Graphics tablet
  • Image scanner
  • Joystick
  • Microphone
  • Mouse
  • Overlay keyboard
  • Real-time clock
  • Trackball
  • Touchscreen

Output devices

The means through which computer gives output are known as output devices. Some examples of output devices are:

  • Computer monitor
  • Printer
  • PC speaker
  • Projector
  • Sound card
  • Video card


Computer main memory comes in two principal varieties:

  • random-access memoryor RAM
  • read-only memoryor ROM


There are thousands of different programming languages—some intended to be general purpose, others useful only for highly specialized applications.

Programming languages
Lists of programming languages Timeline of programming languages, List of programming languages by category, Generational list of programming languages, List of programming languages, Non-English-based programming languages
Commonly used assembly languages ARM, MIPS, x86
Commonly used high-level programming languages Ada, BASIC, C, C++, C#, COBOL, Fortran, PL/I, REXX, Java, Lisp, Pascal, Object Pascal
Commonly used scripting languages Bourne script, JavaScript, Python, Ruby, PHP, Perl




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