8_DigitalSystemDesign

# Simpleoperations alonecannotdo muchbutbillions

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Unformatted text preview: ple Blocks Working Together Example #2 • Google search – Type in search words (input) – Look through large database of web pages (memory) until matches are found (datapath, compare) – When list is found, send it to user (output) Memory Control Datapath Simple Blocks Working Together • Key point – Simple operations alone can not do much, but billions of simple operations per second can do a lot output input Memory Control Datapath 14 Outline • Introduction • What is inside a digital processor? • Building things – Transistors – Building simple things with them – Building bigger things • How chips are built • Building Processors • Questions about engineering, college, grad school, jobs, anything! So What Are Processors Made Of? • Nearly every digital processor in existence is made of basic building blocks called transistors • Think of a transistor as a water valve 15 A Transistor • A water valve controls the flow of water. A transistor controls the flow of electricity. • A water valve does nothing unless there is a difference in water pressure in the pipe. For electricity, this “pressure” is called voltage. higher voltage current “knob” lower voltage A Transistor • For digital circuits, this gets even easier • Think of the transistor as a switch that is either: completely on, or completely off higher voltage “switch” lower voltage 16 What Does “Digital” Mean Anyway? • Analog means something can have any value • Digital means something can have only certain limited values • A binary digital signal can have one of only two possible values – high or low – 1 or 0 – on or off Two Transistors • Try connecting two transistors in a row • Now we’re doing binary logic! • Z = A AND B Z = A &amp; B higher voltage Z A = “switch” #1 B = “switch” #2 lower voltage 17 Two Transistors • Try connecting two transistors in a row • Now we’re doing binary logic! • Z = A AND B Z = A &amp; B higher voltage Z A = “switch” #1 B = “switch” #2 AND lower voltage Two Transistors • Another fundamental building block • Z = A OR B Z = A | B higher voltage Z A = “switch” #1 B = “switch” #2 lower voltage 18 Two Transistors • Another fundamental building block • Z = A OR B Z = A | B higher voltage Z A = “switch” #1 OR B = “switc...
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