The Day I Was Born
Thursday, July 27, 2017
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Week 33 - Power Point - Vacuum Tubes, Transistors, Chips


Word for the Week -- Transistor:

First of all, the image you see is of Eniac--the first 'modern' computer.  It DID NOT use transitors. We'll discuss that later in this lesson (photo credit: www.dicofr.com/chronologie/ chro-00-40.html

A switch is a device which completes or breaks an electrical circuit.

We understand that a light switch turns a light on and off because it lets electricity reach
the bulb when the switch is “on” and prevents the flow of electricity to the bulb when the
switch is “off”.

A TRANSISTOR IS A SWITCH that completes or breaks an electrical circuit--doing the
same thing that regular switches do but doing it in an entirely different way.

A transistor is a switch that has NO MOVING PARTS. It is activated electrically and
becomes conductive (able to allow electricity through) when electricity passes through it.

Transistors are made of a SEMI-CONDUCTOR called SILICON which is made from
sand. It’s conductivity can be changed. It can be EITHER conductive or non-conductive.

In other words when it is on it is conductive
When it is ON, the signal is recognized by the computer as a 1
When it is OFF, the signal is recognized by the computer as a 0

Remembering how the Binary Code (1’s & 0’s) is used by computers it is easy to
understand that transistors are very important components of a computer system.

The first electronic computer, ENIAC used vacuum tubes because transistors had not been
perfected at that time. ENIACs total components filled a large room . Because transistors
are so much smaller than vacuum tubes we know have LAPTOP computers which are
immensely more powerful and less expensive than Eniac.

The history of modern computers started with vaccuum tubes. They were large, hot, fragile, and 'burned out' within a short time.

Then came the transistor--small, fast, durable.

Finally, the CHIP--which handles thousands of  signals in milliseconds.

Today's computers use a combination of small transistors and Chips.

If a modern cell phone contained vacuum tubes instead of transistors  and chips it would be the SIZE  OF THE WASHINGTON MONUMENT. Engineers have been able to continuously
reduce the size of transistors. If they continue to do so SMALLER computing and
telecommunications devices are possible.
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Hands-on:

Power Point

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