Welcome

CSC 480/580 – Digital Logic & Computer Design

Term: Winter 2002Instructor: William T Krieger

CSC 480 Logic Design

The course

3 Common Goals

1. Learn practice2. Show it good

grades3. Have fun... Well,

try to have fun

“I have a dream...”

Details, schmetails

Main page Everything available

online (working on it) Logistics

• 45 minute lecture; break; 45 minute lecture

• Wednesday night lab

CSC 480 Logic Design

The instructor

William T Krieger

BSCS UI 1983 MSCS UIC 1995 15+ years S/W

experience Co-founder

Synopsys, Inc. New to teaching…

well, pretty new

So... Not a logic designer Wrote software to

automate logic design

I’ll follow the book pretty closely

End course with HDL focus (hopefully!)

CSC 480 Logic Design

Why take this course?

Course is required... sort of This is “core” knowledge Overcome “hardware phobia” without much

pain HW versus SW... symbiotic interaction and

interesting contrast:– Faster HW is making more complex SW possible– Use of complex SW in HW design is now prevasive

“...replacement of the manual logic design process makes the design of complex logic much more

efficient”- Mano, page 97

CSC 480 Logic Design

The last 20 years or so The evolution of SW design

– Object-oriented paradigm, widespread usage of high-level languages (C++, Ada, Java)

– Large systems, software engineering, testing and maintenance

– Distributed computing, the net, graphical debugers/GUI builders

REVOLUTION of HW design– Simulation of designs before building them– Synthesis (or compilation) of functional HW design

into lower-level forms (gates, transistors)– Programs can now create logic that competes with

that created by the best human being! SW design is now many times faster... HW

design is now many thousands time faster!

CSC 480 Logic Design

What we will learn

Logic Designo Combinational design: Boolean algebra, logic minimization,

logic gateso Complex combinational structures: muxes, decoder,

encoder, adder, etc.o Sequential design: state machines, flipflops, registers,

PLD’so HDL descriptions

Computer Design Basic structure Control versus datapath Components: register, counters, memory,

programmable devices, cpu Instruction set design, microprocessors

CSC 480 Logic Design

Digital Hardware

Everything built upon two primary (cool) abstractions1’s and 0’s

• Boolean algebra allows formal expression, simplification, manipulation, minimization (G. Boole, 18050’s)

• Niftily maps onto the physical world (usually voltage)The switch

• Mechanism to implement boolean functions: assignment, negation, and, or

• Maps onto the physical world as mechanical relay, transistor (Shockley, et al 1940’s)

• This search continues... biological and atomic-level transistors

For us, these inventions are the equivalent of fire, and the wheel.

CSC 480 Logic Design

MOS transistor as a switch

Transistor revolutionizes “switch”... efficient, reliable, cheap

Many flavors, but CMOS is the most popular semiconductor (chip) technology– MOS = Metal-oxide semiconductor– C = complementary, typically closed

switches and negative logic Example:

CSC 480 Logic Design

Hardware design levels

Behavior

Register transfer

State machines

Logic gates

Boolean algebra

Switches (transistors)

Physical devices (Si)

We will focus on Register transfer level down to boolean algebra

CSC 480 Logic Design

Hardware design today The engineer’s mistress continues to be: size,

complexity, speed, cost, time to market Must work at higher and higher design levels Hierarchical methodology promotes design reuse

(that’s “object-oriented” for us CS majors) Software tools (CAD) are the only alternative now

Automation! Simulators used to verify designs Designs described at a higher level (HDL) and

“compiled” into lower level components Synthesis tools optimize designs to meet specified

criteria or “constraints Analogy: Logic design & assembly language

programming

CSC 480 Logic Design

Logic design example

Binary multiplier– Multiply A x B to get result C

• Input A is 3 bits: a2 a1 a0• Input B is 4 bits: b3 b2 b1 b0• Output C is 6 bits: c5 c4 c3 c2 c1 c0

– Do an example: • What is 101 x 1011?

– Trick• What is a one bit multiply?• Need a couple of adders right?• Cheat where we can

– Go.