Integrated Circuits aka CHIPS
• What’s in this thing????
4 –2

Chapter Goals
• How to make a gate from transistors
• How to make integrated circuits using gates
• The basic gates and their behavior
• How gates are combined into (useful) circuits
4 –3

Chapter Goals
• Describe gates and circuits using:
– Boolean expressions
– Truth Tables
– Logic Diagrams
• Understand half adders, full adders, and binary addition circuits
4 –4

Computers and Electricity
• Transistor A device that can be used to make gates
• Gate A device that performs a basic operation on bit(s)
• Circuits Gates combined to perform more complicated tasks
4 –5

Computers and Electricity
• 3 ways to describe the same thing
– Boolean expressions
– logic diagrams
– truth tables
4 –6

Computers and Electricity
• Boolean expressions A mathematical notation for expressing TRUE/FALSE logic
• Example: F = AB + C
4 –7

Computers and Electricity
• Logic diagram A graphical representation of a circuit
Each type of gate is represented by a specific graphical symbol
• Truth table A table showing all possible input value and the associated output values
4 –8

Gates
• Let’s examine the processing of the following six types of gates
– NOT
– AND
– OR
– XOR
– NAND
– NOR
4 –9

NOT Gate
• A NOT gate accepts one input value and produces one output value
• Aka “an inverter”
Figure 4.1
Various representations of a NOT gate
4 –10

AND Gate
• An AND gate accepts two input signals
• If the two input values for an AND gate are both 1, the output is 1; otherwise, the output is 0
Figure 4.2
Various representations of an AND gate
4 –11

OR Gate
• If the two input values are both 0, the output value is 0; otherwise, the output is 1
Figure 4.3
Various representations of a OR gate
4 –12

NAND and NOR Gates
• The NAND and NOR gates are essentially the opposite of the AND and OR gates, respectively
Figure 4.5
Various representations of a NAND gate
Figure 4.6
Various representations of a NOR gate
4 –15

Constructing Gates
• Transistor A device that acts as a switch, either open or closed (on or off)
– A transistor has no moving parts, yet acts like a switch
– It is made of a semiconductor material, which is neither a particularly good conductor of electricity, such as copper, nor a particularly good insulator, such as rubber
4 –14

Constructing Gates
• Transistor terminals
– Source
– Base
– Emitter
• If the electrical signal is grounded, it is allowed to flow through an alternative route to the ground (literally) where it can do no harm
Figure 4.8
The connections of a transistor
4 –15

Constructing Gates
• It turns out that, because the way a transistor works, the easiest gates to create are the NOT,
NAND, and NOR gates
Figure 4.9
Constructing gates using transistors 4 –16

Combinational Circuits
• Consider the following Boolean expression
A(B + C)
Page 100
Page 101
4 –17

Adders
• At the digital logic level, addition is performed in binary
• Addition operations are carried out by special circuits called, appropriately, adders
4 –18

A Half Adder
• Recall that 1 PLUS 1 = 10 in base two
• In other words: 0 with a carry of 1
0
1
A
0
1
Inputs
1
0
B
0
1
Carry
0
0
0
1
Outputs
Sum
0
1
1
0
4 –19

Page 103
Half Adder Circuit
• Two Boolean expressions: sum = A

B carry = AB
4 –20

A Full Adder
• A circuit called a full adder takes the carry-in value into account
0
1
1
1
1
0
0
A
0
Inputs
1
0
0
1
1
0
1
B Carry In
0 0
1
0
1
0
1
0
1
1
0
1
1
1
Outputs
Carry-
Out Sum
0 0
0
0
1
1
0
1
0
0
1

Integrated Circuits
• We can combine 4 full adders to make a
Four-bit Adder Circuit (about 60 transistors)

Integrated Circuits aka CHIPS
• What’s in this thing????
Chip Fabrication Technology
4 –23

Integrated Circuits
• Integrated circuit (also called a chip ) A piece of silicon on which many gates have been embedded
4 –24

“Silicon Valley”
• Sand is mostly Silicon Dioxide
4 –25

“Silicon Valley”
• Silicon Dioxide ingots and wafers
4 –26

“Silicon Valley”
• Photolithography “Printed” with lots of copies of some circuit
4 –27

Integrated Circuits aka CHIPS
• What’s in this thing????
Computer Architecture: Combining Abstractions into larger
Abstractions
4 –28

Transistors and Gates
4 –29

Integrated Circuits
An simple chip containing 4 independent
NAND gates ( about 8 transistors )
4 –30

Integrated Circuits
• A four-bit Full Adder Circuit

Integrated Circuits
• An Arithmetic Logic Unit (ALU) has adders and other things in it

Integrated Circuits
• A simple Central
Processing Unit, or
CPU has an ALU and other things
• Take Engineering
303 Digital Logic
Design!!

CPU Chips
• A recent CPU chip (Intel Nehelem) 731
Million transistors
4 –34

The Future of the IC
• Global Competition
• Further Integration (ARM)
4 –35