Transcript lecture01

ECSE-2610
Computer Components
& 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 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 World
PCs
Laptop computer
smartcards
Mainframe/supercomputer
Router
CRT projector
Router
printer
Router
Television
Scanner
Data
PDA
Telephone
Fax
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The Digital World
• Information Processing Systems, especially
computers, are driving the world economy.
– The Internet is changing the way we communicate, shop, learn,
COCO is about:
invest, and entertain ourselves.
1. Computer building blocks
•
2. How the building blocks are
This is an amazingly fast moving business!!
assembled to build the
computer
– 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
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Sheer Complexity
Intel Pentium III Chip
• 28 million transistors
• 1.3 billion cycles/sec clock
• Just one part of a computer
• Overall, a computer can have
a billion transistors.
The Design Process is a
systematic way to cope with
all this complexity.
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Basic Ideas
• To design is to represent
• Divide and conquer
• Successive Refinement
• Use Math Tools:
Combinational Logic
Sequential Logic
• Use Software tools
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Traffic Signal Example
N
E
W
S
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 Does
N
E
W
S
N-S
E-W
• 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
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System Requirements
N
E
W
S
N-S
E-W
• 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
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"To Design Is to Represent"
1. English language specification
not precise, can be ambiguous
Start
2. Functional description
more precise
flow charts, program fragments
N-S Green
E-W Red
3. Structural description
modules decomposed into simpler
components
4. Physical description
In terms of logic gates or transistors
after 45 seconds
N-S Yellow
E-W Red
after 15 seconds
N-S Red
E-W Green
after 45 seconds
N-S Red
E-W Yellow
after 15 seconds
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Going from One
Representation 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 Rules
Timing Rules
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Top-Down Design Example
Start
Traffic
Subsystem
N-S Green
N-S Yellow
N-S Red
E-W Green
E-W Yellow
E-W Red
Refine
45 secs
Start
N-S Green
N-S Yellow
N-S Red
E-W Green
E-W Yellow
E-W Red
Light
Sequencer
Timer
15 secs
Refine again
45 secs
Start
Timer
15 secs
N-S Lights
Counter
E-W Lights
Decoder
N-S Green
N-S Yellow
N-S Red
E-W Green
E-W Yellow
E-W Red
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The Process of Building
System
E.g., a group of flip flops form a counter
Modules
groups of gates form flip flops, timers, sequencers etc.
Gates
a group of transistors form a gate
Transistors
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Representations & Technologies
Functional Description
Word description
Blocks
Waveforms
Truth Tables
Boolean Algebra
Computer
Simulation
Gates
Transistors
Computer
Synthesis
Tools
Chip
Design
Rapid Prototyping
Technologies
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Debugging the System
What Can Go Wrong
• Design Flaws
Implementation 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
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Debugging Methods
Simulate before constructing
Systematic testing
Divide and conquer
Use lab Instruments, e.g., Logic Analyzers
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Recap Of Design Process
Design
Iteration
Implementation
Debug
Design
Initial 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 blocks
Composition via wiring
Choose among alternatives to improve the design
Debug
Faulty systems: design flaws, composition flaws, component flaws
Design to make debugging easier
Hypothesis formation and troubleshooting skills
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Do 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 Systems
V
V
+5
+5
1
0
1
Time
–5
Analog: values vary
over a broad range
continuously
Time
–5
Digital: only discrete
values
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Why Prefer Digital ?
Analog systems:
•
Limited precision, errors accumulate, drift
•
Interface circuits (i.e., sensors & actuators) often
analog
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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Binary Digital Systems
• 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
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Boolean Logic Operations
Boolean variable: assume values 0 or 1
Boolean 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
Y
X AND Y
X
Y
X OR Y
X
0
0
1
1
0
1
0
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
0
1
NOT X
1
0
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Traffic Light Example
Start
N-S Green
E-W Red
after 45 seconds
N-S Yellow
E-W Red
after 15 seconds
N-S Red
E-W Green
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
after 45 seconds
N-S Red
E-W Yellow
after 15 seconds
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Variables, 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
Boolean variables:
NSG (1  Green),
EWR (1  Red),
T45 (1  Elapsed),
NEXT (1  Go to next)
Logic Equation:
NEXT = NSG AND EWR AND T45
NSG
EWR
T45
LOGIC
CIRCUIT
NEXT
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Combinational Logic
NSG
EWR
LOGIC
CIRCUIT
NEXT
T45
For this circuit, the outputs are a pure, instant
function of the inputs
• Combinations of inputs define the output
• Also called “memoryless” logic
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Traffic Light Example
Start
N-S Green
E-W Red
after 45 seconds
N-S Yellow
E-W Red
after 15 seconds
N-S Red
E-W Green
after 45 seconds
Combinational Logic
cannot describe the
entire system!!
Why??
N-S Red
E-W Yellow
after 15 seconds
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Sequential Logic
Start
N-S Green
E-W Red
after 45 seconds
N-S Yellow
E-W Red
after 15 seconds
N-S Red
E-W Green
after 45 seconds
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
N-S Red
E-W Yellow
after 15 seconds
Need: storage elements to remember the current state
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Sequential Logic Block Diagram
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!
X1
X2
Xn
Feedback
connection!
-
Logic
Circuit
-
Z1
Z2
Zm
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Traffic Light Example
Other Inputs,
Like Timer Signals
Traffic Light
Controller
New Traffic Light
Controller Configuration
CurrentTraffic
Light Controller
Configuration
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Traffic Light Details
Clock
Timer
Alarms
Next State
Combinational
Logic
S
T
A
T
E
Output
Combinational
Logic
Detailed Light
Control Signals
Current State
Next State Logic
Maps current
state and alarm
events into the
next state
Current State
Binary Storage devices
replaced by next state
when the clock signal arrives
IF controller in state N-S green, E-W red
AND the 45 second timer alarm is on,
THEN the next state becomes N-S yellow,
E-W red at the next clock tick
Output Logic
Current state mapped
into control signals
to change the lights
and to start the event
timers
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Do Activity #2 Now
Due: 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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