Digital Logic

Nowadays, we are all in the age of the digital information world. Digital technology affects everywhere, like TV, smartphone and so on. So this subject is very important for every computing students. There 9 modules I have to take.

Module 1: Digital Logic Overview

in this topic I have learnt how digital system important is in Analog world.  Actually we are living analog world. There limitless amount of colors to paint and countless smells we can smell. And for analog objects also can display data, gather input like Clocks

                             Analog clock

However, Digital signal and objects deal in  the realm of the discrete and discontinuous, it means there is a limited set of value they can be. from this we can see different of Analog and Digit.

Then even real world quantities are mostly analog, but why change to a digital system. Of course it has lots of advantages: ease of design, ease of storage, accuracy and precision are easier to maintain, programmable operation, less affected by noise, ease of fabrication on IC chips. No matter we use digital systems, of course it also has disadvantages like short product half life.

Module 2: Number Systems and Codes

A number system is the set of symbol used to express quantities as the basis for counting, determining order, comparing amount, performing calculations. there are four main type: Decimal Number,Binary Number, Hexadecimal Numbers, Octal Number.

1.Decimal Number We have been  the most familiar with decimal since we could count when we was young. No matter how number is small like 0, or big like 10,000 we all use in decimal number, it can help us understand the rest number system 2.Binary Number The Binary number system is the most important numbering system in digital systems. In computer also use binary number(0,1) 3. Octal Number It includes only the digits 0 through 7, Octal is sometimes used in computing, perhaps most often in modern times in conjunction with file permissions under Unix system 4. Hex Number it base 16: 0-9,A-F. And its  primary use is as a human friendly representation of binary coded values, so it is often used in digital electronics and computer engineering.

Module 3: Logic Gates

Any digital circuit can be built from the most basic building block which are NOT, AND and OR gates. But any digital circuit can also be built from a universal gates such as NAND, NOR, XOR and XNOR gates.

Module 4: Boolean Algebra & Logic Simplification

I knew importance of Boolean Algebra which is used to simplify Boolean expressions which can be convert into one of 2 standard forms: SOP and POS. Simpler expressions lead to simpler circuit realization which, generally, reduce cost, area requirements, and power consumption. The objects of the digital circuit designer is to design and realize optimal digital circuit. There is expression:

Module 5: Combinatoric Logic Circuit

This topic implement by using a universal gates -- NOR or NAND.  Why for final circuit only using a single tpye of gate. Because there are lots of advantage which are: Have to stock only one type of gate, reduce cost, reuse the extra of unused gates to implement other gates.

Module 6: Functions Of Combinatoric Logic

The functions are: Basic Adders, Parallel Binary Adder, Comparators, Decoders, Encoders, Multiplexers(Data Selector), DeMultiplexers(Data DIstributor), Code Converter, Parity Generators/Checkers. Why we need to understand, this is because any digital circuit may consist one or more of these functions which are common, it is produced  as a single IC, also important to know how to use the IC.

Module 7: Latches And Flip-Flops

Latches and flip flops are the basic elements and these are used to store  information. One flip flop and latch can store one bit of data. The main difference between the latches and flip flops is that, a latch checks input continuously and changes the output whenever there is a change in input. But, flip flop is a combination of latch and clock that continuously checks input and changes the output time adjusted by the clock. In this article, we are going to look at the operations of the numerous latches and flip-flops.

Module 8: Counter

The most important part is how to design and analysis. There are two types which are Asynchronous Counter, Synchronous Counter.

Asynchronous Counter steps: 1. Determine number of flip-flop required. 2^n(n is bit) 2. Make a circuit connection 3. draw timing diagram. 

Synchronous Counter steps: 1. Deign n-bit synchronous recycle count-up counter using JK FF 2. Draw state diagram 3. Create next state table 4.Fill in the flip-flop transition table 5. use K-maps to simplify the logic equations 6.Draw the circuit of the counter and implement the circuit.

Analysis of sequential circuit Method 1: 1. Boolean expression for the inputs of each flip flops in the schematic 2. Derive the next state equations 3. from the equation, produce a state table and a state diagram 4. Determine the timing diagram. Method 2: 1. Get Boolean expression of  each flip-flop and output 2. Produce a state table with JK FF transition using the Boolean expression 3. Complete the state table with next state values using JK excitation table, then draw the state diagram.

Module 9: Shift Registers

Shift Registers are sequential logic circuits, capable of storage and transfer of data. They are made up of Flip Flops which are connected in such a way that the output of one flip flop could serve as the input of the other flip-flop, depending on the type of shift registers being created.

Two most important types of shift register counters are Johnson counter and Ring counter. These shift register counters with serial outputs are connected to serial inputs to produce particular pattern of sequences. These shift registers are used as counters because of the specified sequence of states.

              Johnson counter

I really like this subject, not only lecture class, but also there are lots of lab exercise for more understanding. Know how computers work.