Digital Principles and System Design


No area of technology has had or is likely to continue to have more of a profound impact on our lives than digital system development. That’s quite a statement, but its truth is obvious when one considers the many ways we have become dependent on “digitized” technology. To put this in perspective, let us review the various areas in which digital systems play an important role in our lives. As this is done, keep in mind that there is significant, if not necessary, overlap in the digital system technologies that make possible those areas we have come to take for granted: computing, information retrieval, communication, automatic control systems, entertainment, and instrumentation.


If one considers what has happened in, say, the past 15 years, the path of future technological development in the field of digital systems would seem to be limited only by one’s imagination. It is difficult to know where to begin and where to end the task of forecasting digital system development, but here are a few examples in an attempt to accomplish this:

Computer power will continue to increase as the industry moves to 0.10/x (and below) CMOS technology with speeds into the terahertz range and with a demand for more efficient ways to sink the heat generated by billions of transistors per processor operated with supply voltages of one volt or below. There will be dramatic changes in the peripherals that are now viewed as part of the computer systems.

Expect that the mechanically operated magnetic storage systems (disk drives) of today will soon be replaced by a MR (magneto-resistive) technology that will increase the areal storage density (gigabits per square inch) by a factor of 100 to 200, or by OAWD (optically assisted Winchester drive) and MO (magneto-optical) technologies that are expected to increase the areal density even further. Eventually, a holographic storage technology or a proximal probe technology that uses a scanning tunnelling microscopic technique may provide capabilities that will take mass storage to near its theoretical limit. Thus, expect storage systems to be much smaller with enormously increased storage capacity.

Expect that long-distance video conferencing via computer will become as commonplace as the telephone is today. Education will be a major beneficiary of the burgeoning digital age with schools, universities and colleges both public and private being piped into major university libraries and data banks, and with access to the ever-growing WWW.

Expect digital systems to become much more sophisticated and pervasive in our lives. Interconnectivity between “smart” electrically powered systems of all types in the home, automobile, and workplace could be linked to the web together with sophisticated fail-safe and backup systems to prevent large-scale malfunction and possible chaos.

Optical recognition technology will improve dramatically in the fields of robotics, vehicular operation, and security systems. For example, expect that iris and retinal pattern recognition will eventually be used to limit access to certain protected systems and areas, and may even replace digital combination locks, IDs, and licenses for such purposes.

Business networking will undergo dramatic improvements with the continued development of gigabit Ethernet links and high-speed switching technology. Home connectivity will see vast improvements in satellite data service downloading (up to 400 kbps), 56-kbps (and higher) modems that need high-quality digital connections between phones and destination, improved satellite data service with bidirectional data transmission, and DSL (digital subscriber line) cable modem systems.

Finally, there are some really exciting areas to watch. Look for speech recognition, speech synthesis, and handwriting and pattern recognition to dramatically change the manner in which we communicate with and make use of the computer both in business and in the home. Somewhere in the future the computer will be equipped with speech understanding capability that allows the computer to build ideas from a series of spoken words. Thus, expect to see diminished use of the computer keyboard with time as these technologies evolve into common usage.

Revolutionary computer breakthroughs may come with the development of radically different technologies. Carbon nanotube technology, for example, has the potential to propel computer speeds well into the gigahertz range together with greatly reduced power dissipation. The creation of carbon nanotube transistors could signal the dawn of a new revolution in chip development. Then there is the specter of the quantum computer, whose advent may lead to computing capabilities that are trillions of times faster than those of conventional supercomputers. All of this is expected to be only the beginning of a new millennium of invention limited only by imagination. Remember that radically different technological breakthroughs can appear at any time, even without warning, and can have a dramatic affect on our lives, hopefully for the better.


Not yet mentioned are the changes that must take place in the universities and colleges to deal with this rapidly evolving technology. It is fair to say that computer aided design (CAD) or automated design of digital systems is on the upswing. Those who work in the areas of digital system design are familiar with such hardware description languages as VHDL or Verilog, and the means to “download” design data to program PLAs or FPGAs (field programmable gate arrays). It is possible to generate a high-level hardware description of a digital system and introduce that hardware description into circuit layout tools such as Mentor Graphics. The end result would be a transistor-level representation of a CMOS digital system that could be simulated by one of several simulation tools such as HSPICE and subsequently be sent to the foundry for chip creation. The problem with this approach to digital system design is that it bypasses the need to fully understand the intricacies of design that ensure proper and reliable system operation. As is well known, a successful HSPICE simulation does not necessarily ensure a successful design. In the hands of a skilled and experienced designer this approach may lead to success without complications. On the other hand, if care is not taken at the early stages of the design process and if the designer has only a limited knowledge of design fundamentals, the project may fail at one point or another. Thus, as the use of automated (CAD) designs become more attractive to those who lack design detail fundamentals, the chance for design error at the system, device, gate, or transistor level increases. The word of warning: Automated design should never be undertaken without a sufficient knowledge of the field and a thorough understanding of the digital system under consideration — a little knowledge can be dangerous. The trend toward increasing CAD use is not bad, but automated design methods must be used cautiously with sufficient background knowledge to carry out predictably successful designs. Computer automated design should be used to remove the tedium from the design process and, in many cases, make tractable certain designs that would otherwise not be possible. But CAD is not a replacement for the details and background fundamentals required for successful digital system design.

Lesson Plan

Date Period Topics Covered
17.12.2014 3 Number Systems: Decimal, Binary,  Octal, Hexadecimal number
18.12.2014 1 Number Base Conversions: Decimal to Binary, Octal and Hexadecimal, Binary to Decimal, Octal and  Hexadecimal
20.12.2014 5 Octal to  Decimal, Binary and  Hexadecimal, Hexadecimal to  Decimal, Octal and  Binary
23.12.2014 2 Signed Binary Numbers: 1’s and 2’s Complement Arithmetic
24.12.2014 3 Binary codes – 8421, BCD, Excess 3 code, Gray code, BCD Addition and Subtraction
30.12.2014 2 Error detecting & Correcting Codes: Odd and Even Parity Generator and Checker, Hamming Code
31.12.2014 3 Boolean Algebra: Theorems & Properties: Commutative, Associative and Distributive Law, Consensus Theorem, De Morgan’s Theorem. Reduction of Boolean Expressions
03.01.2015 5 Boolean Functions – Canonical Form, Standard Form. Conversion from SOP to POS Form
06.01.2015 2 Simplification of Functions using K-map: Two, Three and Four variables
07.01.2015 3 Logic Gates – Types, Symbol, Truth Table
08.01.2015 1 Design of Binary Half Adder & Full Adder
13.01.2015 2 Design of Binary Half Subtractor & Full Subtractor
20.01.2015 2 Magnitude Comparator- Single Bit, 2 Bit
21.01.2015 3 Code converters – Binary to Gray,  Gray to Binary
22.01.2015 1 Binary  to BCD, BCD to Excess-3, BCD  to Gray
27.01.2015 2 Encoders & Decoders: 2 X 4 , 3 X 8, 4 X 2, 8 X 3
28.01.2015 3 Multiplexers: 4:1, 8:1 16:1 MUX
29.01.2015 1 Demultiplexers: 1:4,1:8, 1:16 DEMUX
31.01.2015 5 Function Realisation using Logic Gates. AND/OR/INVERT to NAND/NOR Logic
10.02.2015 2 Introduction to Latches & Flip-Flops, Types of FFs. SR Flip flop: Excitation Table, Characteristic Equation
11.02.2015 3 JK and Master Slave JK Flip Flop: Excitation Table, Characteristic Equation
12.02.2015 1 D and T Flip Flops: Excitation Table, Characteristic Equation. Conversion of FFs
17.02.2015 2 Design of Shift Registers: SISO, SIPO, PISO, PIPO, Bidirectional Shift Register
18.02.2015 3 Design of Synchronous counters: Procedure, Mod – n Counters using JK and T FFs, Binary Up/ Down Counters
19.02.2015 1 Synchronous Sequential Machines: Mealy Model, Moore Model
21.02.2015 5 Analysis of Synchronous Sequential Circuits: Concepts of State, State Diagram, State table, Transition table
24.02.2015 2 Design of Synchronous Sequential Circuits: State Assignment, State Reduction, Output Table
25.02.2015 3 Design Procedure, Problems
26.02.2015 1 Introduction to  Asynchronous Sequential Logic Circuits: Comparison between Synchronous and  Asynchronous Sequential Circuits
03.03.2015 2 Types of  Asynchronous Sequential Logic Circuits
04.03.2015 3 Concepts of State Table, Flow Table, Primitive Flow Table
05.03.2015 1 State Reduction Techniques – Merger Graph, Implication Table, Races, Cycles, Race Free State Assignment
07.03.2015 5 Analysis of Asynchronous Sequential Circuits: Procedure
10.03.2015 2 Design of Asynchronous Sequential Circuits: Problems
11.03.2015 3 Hazards: Types – Static, Dynamic and Essential Hazards, Elimination of Hazards
12.03.2015 1 Design of Hazard Free Digital Logic Circuits
24.03.2015 2 Introduction & Classification of  Memories: RAM – Static and Dynamic, ROM, PROM, EPROM, EEPROM, UVPROM
25.03.2015 3 Memory Decoding: Coincident decoding, Address Assignment
26.03.2015 1 Programmable Array Logic: Function Realisation using PAL
31.03.2015 2 Programmable Logic Array: Function Realisation using PLA
01.04.2015 3 Sequential Programmable Devices: Simple Programmable Logic Device, Complex Programmable Logic Device, Field Programmable Gate Array
07.04.2015 2 Digital Logic Families: Characteristics – Fan in, Fan Out, Delay Time, Propagation Delay
08.04.2015 3 Types – RTL, DTL, TTL, ECL, CMOS
09.04.2015 1 TTL – Totem Pole output, Current Sinking and Sourcing, TTL Logic Circuits
11.04.2015 5 ECL – Characteristics And Subfamilies, ECL Logic Circuits
15.06.2015 3 CMOS – Operating And Performance Characteristics, CMOS Logic Circuits
16.03.2015 1 Discussion: Binary System And Boolean Algebra
18.03.2015 5 Discussion: Combinational Logic Circuits
21.03.2015 2 Discussion: Synchronous Sequential logic Circuits
22.03.2015 3 Discussion: Asynchronous Sequential Logic Circuits
23.03.2015 1 Discussion: Memory And Programmable Logic Devices


Date Issued Submission Date Assignment Topics Question Paper Solution Manual
Binary System, Boolean Algebra and Combinational Logic Circuits Download Download
Project Design in “Sequential Logic Circuits”
Online Quiz in “Memory and Programmable Logic Devices” Download Download

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