1 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

2 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:

3 The Digital World

4 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

5 Sheer 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.

6 Basic Ideas To design is to represent Divide and conquer Successive Refinement Use Math Tools: Combinational Logic Sequential Logic Use Software tools

7 Traffic Signal Example N S E W N - S E - W Lights for N & S are the same, call them N-S Similarly, we have E-W

8 What 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 E W N - S E - W

9 System 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 E W N - S E - W

10 "To Design Is to Represent" 1. English language specification not precise, can be ambiguous 2. Functional description more precise flow charts, program fragments 3. Structural description modules decomposed into simpler components 4. Physical description In terms of logic gates or transistors Start after 45 seconds after 15 seconds after 45 seconds after 15 seconds N-S Red E-WYellow N-S Red E-W Green N-SYellow E-W Red N-S Green E-W Red

11 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

12 Traffic Subsystem Start N-S Green E-W Red N-S Yellow N-S Red E-W Green E-W Yellow 45 secs Timer Start Light Sequencer 15 secs N-S Green E-W Red N-S Yellow N-S Red E-W Green E-W Yellow Start Timer 15 secs N-S Lights E-W Lights Counter 45 secs Decoder N-S Green E-W Red N-S Yellow N-S Red E-W Green E-W Yellow Top-Down Design Example Refine Refine again

13 The 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

14 Representations & Technologies Word description Functional Description Blocks Waveforms Truth Tables Boolean Algebra Gates Transistors Rapid Prototyping Technologies Chip Design Computer Synthesis Tools Computer Simulation

15 Debugging the System 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 What Can Go Wrong Design Flaws Implementation Flaws

16 Systematic testing Simulate before constructing Use lab Instruments, e.g., Logic Analyzers Debugging Methods Divide and conquer

17 Design Recap Of Design Process 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 Implementation Iteration Debug

18 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.

19 Digital Hardware Systems Analog: values vary over a broad range continuously Digital: only discrete values +5 V –5 101 Time +5 V –5 Time

20 Analog systems: Limited precision, errors accumulate, drift Interface circuits (i.e., sensors & actuators) often analog Why Prefer Digital ? Digital systems: More accurate and reliable Readily available as self-contained, easy to cascade building blocks Computers use digital circuits internally

21 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 Systems

22 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 ANDY XY X ORYXY X NOTX Boolean Logic Operations

23 Traffic 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 Red E-WYellow N-S Red E-W Green N-SYellow E-W Red N-S Green E-W Red

24 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 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 LOGIC CIRCUIT NSG EWR T45 NEXT

25 Combinational 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 LOGIC CIRCUIT NSG EWR T45 NEXT

26 Start after 45 seconds after 15 seconds after 45 seconds after 15 seconds N-S Red E-WYellow N-S Red E-W Green N-SYellow E-W Red N-S Green E-W Red Combinational Logic cannot describe the entire system!! Why?? Traffic Light Example

27 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 Logic Need: storage elements to remember the current state Start after 45 seconds after 15 seconds after 45 seconds after 15 seconds N-S Red E-WYellow N-S Red E-W Green N-SYellow E-W Red N-S Green E-W Red

28 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 Diagram X 1 X 2 X n Logic Circuit Z 1 Z 2 Z m Feedback connection!

29 Traffic Light Example CurrentTraffic Light Controller Configuration Other Inputs, LikeTimer Signals NewTraffic Light Controller Configuration Traffic Light Controller

30 Traffic Light Details Maps current state and alarm events into the next state 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 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 Next State Combinational Logic S T A T E Output Combinational Logic Clock Timer Alarms Current State Detailed Light Control Signals Binary Storage devices replaced by next state when the clock signal arrives Current State Current state mapped into control signals to change the lights and to start the event timers Output Logic Next State Logic

31 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 , and Sec 1.4 This reading is necessary for getting points in the Studio Activity! Studio Session #1 Tuesday/Wednesday