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ECSE-2610ECSE-2610Computer Components Computer Components & Operations (COCO)& Operations (COCO)
Today:
• General Course Information
• First Hour: Introduction to Design– Section 1.1 of Katz’s Textbook
– In-class Activity #1
• Second Hour: Digital Systems– Section 1.2 of Katz
– In-class Activity #2
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Course InformationCourse Information• Lectures (DCC 308) twice a week
– First hour: Lecture + in-class activity– Second hour: Lecture + in-class activity– For each class, need to
» Read ahead» Bring the Katz textbook
• 2-hr Studio sessions (JEC 6309/6314) once a week.– Points for advance preparation!
• All course material and info is on WebCT– Go to RPINFO, Click on WebCT courses, ECSE Dept, COCO.– Login ID same as RCS– Initial password is your birthdate in “mmddyy” format. Change it!
• Adds, Drops, Section Changes…– Contact Ms. Jeanne Denue for all administrative matters– JEC 6049, Phone: 276 - 6313
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The Digital WorldThe Digital World
PCs
printer
Scanner
TelephoneFax
Data
Mainframe/supercomputer
PDA
Laptop computer
Router
Router
Router
Television
CRT projector
smartcards
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The Digital WorldThe Digital World• Information Processing Systems, especially
computers, are driving the world economy.– The Internet is changing the way we communicate, shop, learn,
invest, and entertain ourselves.
• This is an amazingly fast moving business!!– Processors double in speed every 18 months
– The Internet doubles in size every year
• Computers are the most amazing and complex things ever built by mankind
– The Intel Pentium III has 28 million transistors
– It runs at 1.3 billion cycles per second
COCO is about:
1. Computer building blocks
2. How the building blocks are assembled to build the computer
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Sheer ComplexitySheer Complexity
• 28 million transistors
• 1.3 billion cycles/sec clock
• Just one part of a computer
• Overall, a computer can have a billion transistors.
Intel Pentium III Chip
The Design Process is a systematic way to cope with all this complexity.
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Basic IdeasBasic Ideas
• To design is to represent• Divide and conquer• Successive Refinement• Use Math Tools:
Combinational LogicSequential Logic
• Use Software tools
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Traffic Signal ExampleTraffic Signal ExampleN
S
EW
N - S E - W
Lights for N & S are the same, call them N-S
Similarly, we have E-W
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What the System DoesWhat the System Does
• Cycles through the sequence GREEN-YELLOW-RED
• N-S and E-W never GREEN or YELLOW at the same time
• GREEN stays on for 45 seconds, YELLOW for 15, RED for 60
N
S
EW
N - S E - W
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System RequirementsSystem Requirements
• speed: compute changes in under 100 ms
• power: consume less than 20 watts
• board area: implement in less than 20 square cm
• cost: less than $20 to manufacture
N
S
EW
N - S E - W
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"To Design Is to Represent""To Design Is to Represent"
1. English language specificationnot precise, can be ambiguous
2. Functional descriptionmore preciseflow charts, program fragments
3. Structural descriptionmodules decomposed into simpler components
4. Physical descriptionIn terms of logic gates or transistors
Start
after 45 seconds
after 15 seconds
after 45 seconds
after 15 seconds
N-S RedE-W Yellow
N-S RedE-W Green
N-S YellowE-W Red
N-S GreenE-W Red
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Going from One Going from One Representation to AnotherRepresentation to Another
Top Down: Complex functions replaced by more primitive functions
Bottom Up: Build more and more complex assemblies out of smaller parts,
respecting the rules of composition
Rules of Composition: Electrical RulesTiming Rules
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TrafficSubsystem
StartN-S Green
E-W Red
N-S YellowN-S Red
E-W GreenE-W Yellow
45 secs
TimerStart Light Sequencer
15 secs
N-S Green
E-W Red
N-S YellowN-S Red
E-W GreenE-W Yellow
Start Timer
15 secs
N-S Lights
E-W Lights
Counter
45 secs
Decoder
N-S Green
E-W Red
N-S YellowN-S Red
E-W GreenE-W Yellow
Top-Down Design ExampleTop-Down Design Example
Refine
Refine again
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The Process of BuildingThe Process of Building
E.g., a group of flip flops form a counter
groups of gates form flip flops, timers, sequencers etc.
a group of transistors form a gate
Gates
Transistors
Modules
System
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Representations & TechnologiesRepresentations & Technologies
Word description
Functional Description
Blocks
Waveforms
Truth Tables
Boolean Algebra
Gates
Transistors
Rapid PrototypingTechnologies
ChipDesign
ComputerSynthesisTools
Computer Simulation
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Debugging the SystemDebugging the System
• Design FlawsImplementation does not meet functional specification
Logic design is incorrect (wrong function implemented)
• Implementation Flaws
Individual modules function correctly but their compositions do not
Misunderstanding of interface and timing behavior
Wiring mistakes
• Component Flaws
What Can Go Wrong
• Design Flaws
• Implementation Flaws
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Systematic testingSystematic testing
Simulate before constructing
Use lab Instruments, e.g., Logic Analyzers
Debugging MethodsDebugging Methods
Divide and conquerDivide and conquer
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Design
Recap Of Design ProcessRecap Of Design Process
DesignInitial concept: what is the function performed by the object?Constraints: How fast? How much area? How much cost?Refine abstract functional blocks into more concrete realizations
Implementation
Assemble primitives into more complex building blocksComposition via wiringChoose among alternatives to improve the design
DebugFaulty systems: design flaws, composition flaws, component flawsDesign to make debugging easierHypothesis formation and troubleshooting skills
ImplementationIteration
Debug
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Do Activity #1 NowDo Activity #1 Now
• Reference: –Section 1.1 of Katz Textbook
–Bring the book to each class from now on
• If you are on the wait list, put “W” for the section number.
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Digital Hardware SystemsDigital Hardware Systems
Analog: values vary over a broad range continuously
Digital: only discrete values
+5
V
–5
1 0 1
Time
+5 V
–5
Time
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Analog systems:
• Limited precision, errors accumulate, drift
• Interface circuits (i.e., sensors & actuators) often analog
Why Prefer Digital ? Why Prefer Digital ?
Digital systems:
• More accurate and reliable
• Readily available as self-contained, easy to cascade building blocks
• Computers use digital circuits internally
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• Just two discrete values: yes/on/5 volts/current flowing/magnetized North/true/"1" no/off/0 volts/no current flowing/magnetized South/false/"0"
• Two kinds of systems:
1. Combinational: Described by Boolean Logic
2. Sequential: Described by State Machine Theory
Binary Digital SystemsBinary Digital Systems
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Boolean variable: assume values 0 or 1Boolean equation: also called “logic expression”
If a logic expression is false, it has value 0 If a logic expression is true, it has value 1
Basic Boolean Operations: AND, OR, NOT
X AND Y 0 0 1 1
X Y
0 1 0 1
0 0 0 1
X OR Y X Y
0 0 1 1
0 1 0 1
0 1 1 1
X NOT X
0 1
1 0
Boolean Logic OperationsBoolean Logic Operations
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Traffic Light ExampleTraffic Light Example
IF N-S is green
AND E-W is red
AND 45 seconds has elapsed since the last light change
THEN we can advance to the next light configuration
IF N-S is green
AND E-W is red
AND 45 seconds has elapsed since the last light change
THEN we can advance to the next light configuration
Start
after 45 seconds
after 15 seconds
after 45 seconds
after 15 seconds
N-S RedE-W Yellow
N-S RedE-W Green
N-S YellowE-W Red
N-S GreenE-W Red
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Variables, Equation, and CircuitVariables, Equation, and Circuit
IF N-S is green
AND E-W is red
AND 45 seconds has elapsed since the last light change
THEN we can advance to the next light configuration
IF N-S is green
AND E-W is red
AND 45 seconds has elapsed since the last light change
THEN we can advance to the next light configuration
Boolean variables:
NSG (1 Green), EWR (1 Red), T45 (1 Elapsed), NEXT (1 Go to next)
Logic Equation: NEXT = NSG AND EWR AND T45
LOGICCIRCUIT
NSG
EWR
T45
NEXT
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Combinational LogicCombinational Logic
For this circuit, the outputs are a pure, instant function of the inputs
• Combinations of inputs define the output• Also called “memoryless” logic
For this circuit, the outputs are a pure, instant function of the inputs
• Combinations of inputs define the output• Also called “memoryless” logic
LOGICCIRCUIT
NSG
EWR
T45
NEXT
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Start
after 45 seconds
after 15 seconds
after 45 seconds
after 15 seconds
N-S RedE-W Yellow
N-S RedE-W Green
N-S YellowE-W Red
N-S GreenE-W Red
Combinational Logic cannot describe the
entire system!!
Why??
Traffic Light ExampleTraffic Light Example
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Traffic light controller sequences infinitely through four states
Inputs and outputs overlap
Outputs depend on inputs and the entire history of execution!
That is, the circuit has memory Circuit only needs a summary representation of
the past: a limited number of unique configurations called state
Sequential LogicSequential Logic
Need: storage elements to remember the current stateNeed: storage elements to remember the current state
Start
after 45 seconds
after 15 seconds
after 45 seconds
after 15 seconds
N-S RedE-W Yellow
N-S RedE-W Green
N-S YellowE-W Red
N-S GreenE-W Red
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New component: storage elements to remember the current state
Circuit has feedback connections
output and new state is a function of the inputs and the old state
So, the fed back outputs are the state!
Sequential Logic Block DiagramSequential Logic Block Diagram
- - -
X 1 X 2 X n
LogicCircuit
Z 1 Z 2 Z m
- - -
Feedback connection!
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Traffic Light ExampleTraffic Light Example
Current Traffic Light Controller Configuration
Other Inputs, Like Timer Signals
New Traffic Light Controller Configuration
Traffic Light Controller
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Traffic Light DetailsTraffic Light Details
Maps current state and alarm events into the next state
IF controller in state N-S green, E-W redAND the 45 second timer alarm is on,THEN the next state becomes N-S yellow, E-W red at the next clock tick
IF controller in state N-S green, E-W redAND the 45 second timer alarm is on,THEN the next state becomes N-S yellow, E-W red at the next clock tick
Next StateCombinational
Logic
S T A T E
Output Combinational
Logic
Clock Timer
Alarms
Current State
Detailed Light Control Signals
Binary Storage devices replaced by next statewhen the clock signal arrives
Current StateCurrent state mapped into control signalsto change the lights and to start the eventtimers
Output LogicNext State Logic
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Do Activity #2 NowDo Activity #2 NowDue: End of Class Today
RETAIN THE LAST PAGE (#3)!!
For Next Class:• Bring Randy Katz Textbook
• Required Reading:– Sec 1.1, 1.2, and 1.3 of Katz
– Omit Sec 1.3.5 - 1.3.7, and Sec 1.4
• This reading is necessary for getting points in the Studio Activity!
• Studio Session #1 Tuesday/Wednesday
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