A Brief History of Computers From Prehistory to the 21 st Century David A. Lewis Hyndman Middle Senior High School Hyndman, PA 15545

Part Four Electronic Devices Use Electronic Switching Devices Vacuum tubes, transistors, & integrated circuits

Vacuum Tube Also called Electron Tube Also called Electron Tube Or Thermionic Valve Or Thermionic Valve Switch, Amplify, or Modify a signal by controlling the flow of Electrons Switch, Amplify, or Modify a signal by controlling the flow of Electrons Critical to development of Radio, TV, Hi-Fi Sound Recording, Radar, Telephone, and Computers Critical to development of Radio, TV, Hi-Fi Sound Recording, Radar, Telephone, and Computers This is a common tube used in radios & TVs

Vacuum Tube Filament (cathode) releases electrons when heated Filament (cathode) releases electrons when heated Electrons drawn to Plate (anode) Electrons drawn to Plate (anode) Sealed in a glass tube with air removed Sealed in a glass tube with air removed Not energy efficient Not energy efficient Click to See How Vacuum Tubes Really Work

Cool Video Showing how vacuum tubes (valves) work in amplifying music Showing how vacuum tubes (valves) work in amplifying music

ENIAC – proved it was possible Electrical Electrical Numerical Integrator and Computer Developed Developed by U.S.Army and University of Pennsylvania late in World War II (1945) Made Made to compute ballistics tables for artillery

ENIAC Filled a 30 X 50 room. Filled a 30 X 50 room. Weighed 30 tons Weighed 30 tons Programmable- could be set to perform many other tasks Programmable- could be set to perform many other tasks Could do 100,000 calculations per second Could do 100,000 calculations per second Fully Automatic Fully Automatic

ENIAC – a small part

ENIAC Programmers Early Programmers were all women! Early Programmers were all women!

ENIAC – Size and Scale This photo shows less than half of the ENIAC

Eniacs 19,000 Tubes Checking vacuum tubes Checking vacuum tubes

No Air Conditioning!

Transistors Fundamental to all modern electronic devices Fundamental to all modern electronic devices Greatest invention of the 20 th century Greatest invention of the 20 th century 1947 – Bell Labs 1947 – Bell Labs Regulates the flow of electrical current Regulates the flow of electrical current Acts as a switch Acts as a switch Click to read about: How Do Transistors Work?

The First Transistor Created at Bell Labs Created at Bell Labs Small, light weight Small, light weight Cheap to produce Cheap to produce Made portable electronics possible Made portable electronics possible

How does a transistor work? A transistor is a channel with a gate. A transistor is a channel with a gate. Closed gate blocks the passage of the electron - counts as a zero Closed gate blocks the passage of the electron - counts as a zero Open gate allows electron through - counts as one. Open gate allows electron through - counts as one. Those ones and zeros are the basis for binary counting. Those ones and zeros are the basis for binary counting. Click for a simple Flash explanation Click for a simple Flash explanation Click for a simple Flash explanation Click for a simple Flash explanation Learn more about transistors at: Transistors Launch the Computer RevolutionTransistors Launch the Computer Revolution

Transistor Computer 1953 University of Manchester 1953 University of Manchester Experience with building transistorized circuits Experience with building transistorized circuits 7 machines were built 7 machines were built

Transistor Computer

The Integrated Circuit 1958 Jack Kilby: Made all components from one block of semiconductor (Texas Instruments) Jack Kilby: Made all components from one block of semiconductor (Texas Instruments) Robert Noyce: Added a layer of metal to form the wires (Fairchild Semiconductor - Founder of Intel) Robert Noyce: Added a layer of metal to form the wires (Fairchild Semiconductor - Founder of Intel) No More Wires! No More Wires! No more hand assembly of components No more hand assembly of components

The First IC Jack Kilby and His First Integrated Circuit Jack Kilby and His First Integrated Circuit

IC Co-Inventor Robert Noyce Robert Noyce Co-founder of Intel Co-founder of Intel Developed the Microchip Developed the Microchip Mayor of Silicon Valley Mayor of Silicon Valley

Integrated Circuits (IC) Thin slices of silicon crystal Thin slices of silicon crystal Electrical components are etched onto the surface Electrical components are etched onto the surface Precise areas altered by chemical dopants Precise areas altered by chemical dopants Wire mesh makes the connections Wire mesh makes the connections Click to learn more about integrated circuits

Wafer Close-up photo of an IC wafer Close-up photo of an IC wafer Diamond saw used to cut the chips apart Diamond saw used to cut the chips apart

IC Packaging

The Microchip

Evolution of The Microprocessor

Summary Vacuum Tubes – 1907 Vacuum Tubes – 1907 First electronic switching device First electronic switching device Radio, TV, Radar, Telephone, Computers Radio, TV, Radar, Telephone, Computers ENIAC the First Electronic Computer – 1945 ENIAC the First Electronic Computer – 1945 Transistors Transistors Small, Lightweight, Cheap to Produce Small, Lightweight, Cheap to Produce Portability Made Possible Portability Made Possible Transistor Computer Transistor Computer

Summary, cont. Integrated Circuit – 1958 Integrated Circuit – 1958 Transistors and wires etched into silicon Transistors and wires etched into silicon Miniature circuits Miniature circuits Microchips Microchips Perfected in 1980s Perfected in 1980s Mass-produced Mass-produced Basis for all modern electronics Basis for all modern electronics Brains of our computers Brains of our computers

Just For Fun! White & Nerdy by Weird Al Yankovic 2007