1. ACOE161 – Digital Logic for Computers
Dr. Konstantinos Tatas
Office 107, FRC building

2. Some Information
Instructor Details
Main Textbook

3. Course Information Programme of Studies:
BSc in Computer Engineering, BSc in Computer Science
Name of the module:
ACOE161 – Digital Logic for Computers
Target group:
Computer Engineering – Computer Science students
Level of the unit:
BSc – 2nd Semester
Fundamental
Entrance requirements:
None
Language of instruction:
English
Number of ECTS credits:
7 (Average student working time: 175 hours)

4. Course Overview
Introduction to logic design, digital systems and computer architecture concepts
Topics include
Digital computer systems
Number systems
Arithmetic operations
Combinational logic circuits and design
Sequential circuits
Registers and counters
Memory and programmable logic devices
Introduction to sequencing and control

5. Course Assessment
Test 1 – 10% (approx. week 6)
Test 2 – 10% (approx. week 11)
Laboratory work – 20% (5% pre-lab reports, 15% experiments)
Final – 60%

6. Signal An information variable represented by physical quantity.
For digital systems, the variable takes on discrete values.
Two level, or binary values are the most prevalent values in digital systems. 
Binary values are represented abstractly by:
digits 0 and 1
words (symbols) False (F) and True (T)
words (symbols) Low (L) and High (H)
and words Off and On.
Binary values are represented by values or ranges of values of physical quantities

7. Signal Examples Over Time
Continuous in value & time
Analog
Digital
Discrete in value & continuous in time
Asynchronous
Discrete in value & time
Synchronous

8. Signal Example – Physical Quantity: Voltage
Threshold Region
The HIGH range typically corresponds to binary 1 and LOW range to binary 0. The threshold region is a range of voltages
for which the input voltage value cannot be interpreted reliably as either a 0 or a 1.

9. Binary Values: Other Physical Quantities
What are other physical quantities represent 0 and 1?
CPU Voltage
Disk CD
Dynamic RAM
Magnetic Field Direction
Surface Pits/Light
Electrical Charge

10. ANALOG GOES DIGITAL
Photography
Video
Audio
Automobile applications
Telephony/Telecommunications
Traffic lights
Special effects

11. ADVANTAGES OF DIGITAL PROCESSING
Reproducibility of results
Ease of design
Programmability
Speed
Noise tolerance

12. 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

13. 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)

14. 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?

15. A Digital Computer Example
Inputs: Keyboard, mouse, modem, microphone
Outputs: CRT, LCD, modem, 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.
Synchronous or Asynchronous?