Relay Vacuum Tubes and CRT Individual Transistors Integrated Circuit (IC) PCB Board Masks, Ingot, Wafers Chips, Boards Video: Transitorized

The Bipolar NPN Transistor

The base-emitter junction is forward biased, the base-collector junction is reverse biased.

The transistor is bipolar because both charge carriers (holes and electrons) are present.

Fabricating a transistor on a single piece of doped silicon wikipedia CNN.com

Basic Amplifier Circuit using the NPN Bipolar Transistor http://www.tpub.com

Model of first Transistor c. 1947

http://www.porticus.org/bell

The Field Effect Transistor (FET)

Electricity flows from the Source to the Drain when an electric field is applied to the Gate.

Field Effect Transistor (FET)

FETs are tiny switches that can open and close very quickly.

A negative voltage will turn this p channel transistor on. ‘On’ means there is a connection between the Source and Drain.

http://www.answers.com

Before the transistor, there was the Vacuum Tube ► Also used to amplify signals ► Also used as a switch

http://www.privateline.com

Electrons are “boiled” off the cathode and attracted to the anode because of the applied voltage.

A grid controls the electron flow.

The signal to be amplified is connected to the grid. A small signal controls a much current.

Cathode Ray Tube (CRT)

Still is use Today ► Vacuum Tube, Electron Gun, Fluorescent Screen, and Coils which accelerate and deflect the electron beam ► Magnetron ► Power Amplifiers

ENIAC in 1946 ► ► ► ► ► ► ► ► ► ► First electronic computer Designed for the Army $500,000 19,000 Vacuum Tubes 1000 Relays 200 KW of power Filled multiple rooms (700 sq. ft) Soldered and constructed by hand by the University of Penn.

Slow Unreliable

Hearing Aids - the first commercial devices that used transistors c. 1953

http://blog.modernmechanix.com

► Individual Parts ► Integration of parts required hand wiring Early Sony Transistor Radio

Richard Feynman

As told to American Physical Society in 1959, 'People tell me about miniaturization, and how far it has progressed today. There is a device on the market by which you can write the Lord's Prayer on the head of a pin. But that's nothing . Why can we not write the entire 24 volumes of the Encyclopedia Britannica on the head of a pin?

Feynman asked why wires couldn’t be 90 nm

The birth of the integrated circuit (IC) ► ► ► 1947- using silicon as a transistor is discovered 1959- Texas Instruments put 10 transistors on one piece of silicon. First company to use Silicon instead of Germanium Used in Apollo Program to achieve moon landing – transistors integrated on pieces of silicon offered lower power and weight. 1961-69

Moore’s Law (Gordon Moore – Intel Founder)

Intel 4004

The World’s first Microprocessor, made in 1971 Computer on a chip!

It had 2300 transistors and ran at 740 KHz.

It could execute 45 instructions.

Could execute 96,000 instructions per second As powerful as the ENIAC

Where’s the chip?

http://www.computerhistory.org/semiconductor/

Chips can have up to a billion transistors built on a small piece of silicon.

CMOS stands for ‘Complimentary Metal Oxide Semiconductor’. This means CMOS chips contain both pMOS and nMOS transistors.

http://www.britannica.com

Integrated Circuit Manufacturing Process

Clean Room

Masks, Photoresist, & a developing process called Photolithography transfers patterns to the wafer http://chem.chem.rochester.edu

http://info.tuwien.ac.at

What do computers do?

► Very simple operations  Every computer has a small set of simple instructions it can perform (Instruction Set) ► Operate on 1’s and 0’s (binary data)   Numbers are represented with 1’s and 0’s Letters, symbols, & keystokes are represented with 1’s and 0’s.

► Do the operations very fast ► Complex operations are broken down into many VERY simple operations.

Modern Computers might process 64 bits at a time

0101010001110101001010101010101 0101000100101010001010101001011 00 1110000101010101010100000101010 1000010111010010111010101010101 01 1010100101011101101000101011101 0101011101001010000010110111110 11 1011111010010000010101101010110 1010101010111100101010001010100 10 Etc.

Binary Codes are base-2 numbers

2097  1011  2 X 10 3 + 0 X 10 2 + 9 X 10 1 versus + 7 X 10 0 = 2,097 1 X 8 + 0 X 4 + 1 X 2 + 1 X 1 = 11 ASCII (American Standard Code for Information Exchange) Each letter, punctuation mark, etc. has a unique 8-bit code.

00100110 01010101 00101110  FUN The Declaration of Independence, your love letters and emails, the Bible are huge numbers .

All data can be digitized with out degradation over time.

Analog sound waves can be stored directly in their analog form, e.g. by cutting grooves on vinyl.

http://www.optics.rochester.edu

http://jvsc.jst.go.jp

www.bbc.co.uk

Photographic picture is an analog image. The photo represents the original image. Note there is a continuous range of hues and shades in negative film. Copying from analog data usually results in loss of data. Copies from copies do not look as good as originals.

A digital image is made up of many pixels, each pixel having one color out of a fixed number of possible colors.

Each pixel is a digital number. Copying does not result in loss of data.

http://photo.net/equipment/digital/basics

Data can be converted to binary ½ the (digitizing) using an analog to digital converter Periodically take a sample, at a rate of at least frequency. The more samples the more information is captured. The more bits used the closer the sample approximates the original.

/www.webbasedprogramming.com

Logical ‘AND’

Example: Series Circuit with battery, two switches and a light bulb.

Logical ‘OR’

Example: Two switches in parallel, with a bulb and battery.

Inverter or NOT gate

Example: Series circuit with switch in parallel with bulb.

NAND and NOR

Not-AND  NAND Not-OR  OR Easier to make than AND and OR

MOSFET Transistor as a Switch

PNP type – negative voltage (a ‘0’) turns this transistor “on”

NPN type – a postive voltage (a ‘1’) turns this transistor “on”

Transistors perform logical operations http://www.iclayoutonline.com

Build a Truth Table for this Circuit:

Exclusive OR (XOR)

• Inequality Tester • 1-Bit Adder Only 16 transistors

XORs and NOR make an equality tester

A1 B1 A2 B2 How could this circuit be used to implement your word processors ‘search’ function? How would you find “FUN” in your document?

XORs, ANDs, and OR make an Adder Circuit

     

Summary

Transistors act like on/off switches Computers operate on long words (64 bits) of 1’s and 0’s Sophisticated operations can be broken down into many very simple operations.

Complex circuits are built from simpler circuits (Equality Tester made from XOR and NOR) Basic logic operations are done with a few transistor.

Modern computers could be made with mechanical relays.

Sources

http://www.pbs.org/transistor/