History of Computers Week 2

Introduction

• The term "computer" initially referred to humans performing calculations, recorded as early as 1613.
• Human computers required extensive training in mathematics for specialized tasks.

Evolution of Computers

• Six generations of computers exist: pre-modern era, first, second, third, fourth, and fifth generations.
• Pre-modern era includes manual-mechanical, electromechanical, and electronic devices.

Pre-modern Era Devices

• Manual-Mechanical Devices: Operated manually by users.

  • Tally Sticks: Ancient memory aids for documenting numbers.
  • Abacus: Considered the first computing device, using beads to perform calculations; invented in China.
  • Napier’s Bones: Created by John Napier in 1614 for arithmetic calculations.
  • Oughtred’s Slide Rule: Mechanical device for multiplication and division, invented by William Oughtred.
  • Pascaline Calculator: Mechanical adding machine by Blaise Pascal, introduced in 1642.
  • Stepped Reckoner: Invented by Gottfried Wilhelm Leibniz in 1672; performed basic arithmetic operations.

• Babbage’s Engines:

  • Difference Engine: Automated computation of mathematical tables by Charles Babbage.
  • Analytical Engine: A fully automatic machine capable of any calculation.

• Arithmometer: Invented by Thomas de Colmar in 1820; became the first commercially successful calculator.

Electronic Devices

• Developed using circuit boards and transistors, moving away from mechanical relays.
  • ABC (Atanasoff-Berry Computer): The first digital computer for solving simultaneous equations.
  • ENIAC (Electronic Numerical Integrator and Calculator): The first fully electronic general-purpose digital computer.

Generations of Computers

• First Generation (1951-1958): Utilized vacuum tubes; processing speed of 1,000 instructions/sec.

  • Notable examples: UNIVAC (first commercial computer) and IBM 701.

• Second Generation (1959-1963): Featured transistors; processing speed of 1,000,000 instructions/sec.

  • Example: TRADIC, the first transistorized computer.

• Third Generation (1964-1970): Introduced integrated circuits; processing speed of 10,000,000 instructions/sec.

  • Example: IBM System/360, used widely in business and science.

• Fourth Generation (1971-present): Microprocessors or large-scale integrated circuits; processing speed over 100,000,000 instructions/sec.

  • Introduction of GUIs and the networked environment leading to the Internet.

• Fifth Generation (Present-Future): Focuses on Artificial Intelligence (AI); uses parallel processing and superconductors for advanced capabilities.

Classification of Computers

• According to Purpose:

  • General-Purpose Computers: Versatile machines like PCs, capable of running various applications.
  • Digital Computers: Specialized for counting; operates on discrete values.
  • Analog Computers: Handle continuous variables; used in scientific and engineering applications, e.g., speedometers.
  • Hybrid Computers: Combine features of analog and digital computers for specialized tasks.

• According to Capacity:

  • Supercomputers: The most powerful in speed and accuracy; execute trillions of instructions per second (FLOPS).
  • Mainframe Computers: Large systems for multiple simultaneous user access; handle massive data volumes.
  • Minicomputers: Mid-range devices popular in late 1960s; now largely replaced by personal computers.
  • Microcomputers: Small, affordable, and widely used; commonly known as personal computers (PCs).