Digital Systems

BIL- 223 Logic Circuit Design

Ege UniversityDepartment of Computer

Engineering

Why Study Digital Design? Look “under the hood” of computers

Solid understanding --> confidence, insight, even better programmer when aware of hardware resource issues

Electronic devices becoming digital Sound recorders, cameras, cars, cell phones... Known as “embedded systems”

Thousands of new devices every year Computers as integral parts of other products Designers needed

1995

Portablemusic players

1997

Satellites

1999

Cell phones

2001

DVDplayers

Videorecorders

Musicalinstruments

2003

Cameras TVs ???

2005 2007

Computer Engineering

concentrate more on the computational process at an abstract level as opposed to how the computation is accomplished with metal and silicon (wires and transistors).

views a computing system in terms of what it can do rather than how.

they often employ sophisticated abstract mathematical or logic-based models of computing systems as way to understand their capabilities.

Theory & Practice• Abstraction

• Analysis & design of digital electronic circuits

• Fundamental concepts in the design of digital systems

• Basic tools for the design of digital circuits

• Designed by Charles Babbage from 1834 – 1871

• Considered to be the first digital computer

• Built from mechanical gears, where each gear represented a discrete value (0-9)

• Babbage died before it was finished

The Analytical Engine

• Introduced binary variables

• Introduced the three fundamental logic operations: AND, OR, and NOT.

George Boole, 1815-1864

John Bardeen, William Shockley and Walter Brattain

• Invented in 1947 the first transistor

• Jointly awarded the 1956 Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect."

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948.

Inventors of Integrated Circuits

Robert Noyce

Jack KilbyNobel Prize in Physics 2000

Moore’s Law

Exponential growth

Transistor count will be doubled every 18 months Gordon Moore, Intel co-founder

42millions

2,250

1.7 billions

Bill Gates, Microsoft founder

“No one will need more than 637 kb of memory for a personal computer. 640K ought to be enough for anybody.” 1981

“I think there is a world market for maybe five computers.” 1943 

Thomas Watson, IBM Chairman

Epic Fail

DIGITAL & COMPUTER SYSTEMS - Digital System

• Takes a set of discrete information inputs and discrete internal information (system state) and generates a set of discrete information outputs.

System State

DiscreteInformationProcessingSystem

DiscreteInputs

DiscreteOutputs

Types of Digital Systems No state present

Combinational Logic SystemOutput = Function(Input)

State present State updated at discrete times => Synchronous Sequential System State updated at any time =>Asynchronous Sequential SystemState = Function (State, Input)Output = Function (State) or Function (State, Input)

Digital System Example:

A Digital Counter (e. g., odometer):

1 30 0 5 6 4Count Up

Reset

Inputs: Count Up, Reset

Outputs:Visual Display State: "Value" of stored

digits

Synchronous or Asynchronous?

Digital Computer Example

Synchronous or Asynchronous?

Inputs: keyboard, mouse, wireless, microphone

Outputs: LCD screen, wireless, speakers

Memory

Controlunit Datapath

Input/Output

CPU

Hierarchy of Computation

ProblemProblem AlgorithmsAlgorithms

Programming inHigh-Level LanguageProgramming inHigh-Level Language

Compiler/Assembler/LinkerCompiler/Assembler/Linker

Instruction Set Architecture (ISA)Instruction Set Architecture (ISA) BinaryBinary

System architectureSystem architecture

Target Machine (one implementation)Target Machine (one implementation)Micro-architectureMicro-architecture

Functional units/Building blocksFunctional units/Building blocks

Gates Level Design Gates Level Design

TransistorsTransistors ManufacturingManufacturing

Hierarchy of Computation

ProblemProblem AlgorithmsAlgorithms

Programming inHigh-Level LanguageProgramming inHigh-Level Language

Compiler/Assembler/LinkerCompiler/Assembler/Linker

Instruction Set Architecture (ISA)Instruction Set Architecture (ISA) BinaryBinary

System architectureSystem architecture

Target Machine (one implementation)Target Machine (one implementation)Micro-architectureMicro-architecture

Functional units/Building blocksFunctional units/Building blocks

Gates Level Design Gates Level Design

TransistorsTransistors ManufacturingManufacturing

System LevelSystem Level

Human LevelHuman Level

RTL Level RTL Level Logic Level Logic Level Circuit Level Circuit Level Silicon Level Silicon Level

OUR SCOPE IN THIS COURSEOUR SCOPE IN THIS COURSE

From Desing to Implementation