1. Department of Computer Engineering
Ege University
Department of Computer Engineering
Digital Systems
BIL- 223 Logic Circuit Design

2. 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
Portable
music players
1997
Satellites
1999
Cell phones
2001
DVD
players
Video
recorders
Musical
instruments
2003
Cameras
TVs
???
2005
2007

3. 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.

4. 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

5. The Analytical Engine 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

6. George Boole, 1815-1864 Introduced binary variables
Introduced the three fundamental logic operations: AND, OR, and NOT.

7. 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.

8. Inventors of Integrated Circuits
Robert Noyce
Jack Kilby
Nobel Prize in Physics 2000

9. Moore’s Law Transistor count will be doubled every 18 months
1.7 billions
42millions
Exponential growth
2,250
Transistor count will be doubled every 18 months
 Gordon Moore, Intel co-founder

10. Epic Fail
“No one will need more than 637 kb of memory for a personal computer. 640K ought to be enough for anybody.” 1981
Bill Gates, Microsoft founder
“I think there is a world market for maybe five computers.” 1943 
Thomas Watson, IBM Chairman

11. 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
Discrete
Information
Processing
System
Inputs
Outputs

12. Types of Digital Systems
No state present
Combinational Logic System
Output = Function(Input)
State present
State updated at discrete times
=> Synchronous Sequential System
State updated at any time
=>Asynchronous Sequential System
State = Function (State, Input)
Output = Function (State) or Function (State, Input)

13. Digital System Example:
A Digital Counter (e. g., odometer):
Count Up 1 3 5 6 4
Reset
Inputs:
Count Up, Reset
Outputs:
Visual Display
State:
"Value" of stored digits
Synchronous or Asynchronous?

14. Digital Computer Example
Memory
Control
CPU
Datapath
unit
Inputs: keyboard, mouse, wireless, microphone
Outputs: LCD screen, wireless, speakers
Answer: Part of specification for a PC is in MHz. What does that imply? A clock which defines the discrete times for update of state for a synchronous system. Not all of the computer may be synchronous, however.
Input/Output
Synchronous or Asynchronous?

15. Hierarchy of Computation
Programming in
High-Level Language
Compiler/Assembler/
Linker
Problem
Algorithms
Instruction Set Architecture (ISA)
Binary
System architecture
Target Machine
(one implementation)
Micro-architecture
Functional units/
Building blocks
Gates Level
Design
Transistors
Manufacturing

16. Hierarchy of Computation
Programming in
High-Level Language
Compiler/Assembler/
Linker
Problem
Algorithms
Instruction Set Architecture (ISA)
Binary
System architecture
Target Machine
(one implementation)
Micro-architecture
Functional units/
Building blocks
Human Level
OUR SCOPE IN THIS COURSE
System Level
RTL Level
Gates Level
Design
Logic Level
Circuit Level
Silicon Level
Transistors
Manufacturing

17. From Desing to Implementation