School of Computer and Communication Engineering, UniMAP Mohd ridzuan mohd nor DKT 122/3 - DIGITAL SYSTEM I Chapter 1: Digital Concepts

School of Computer and Communication Engineering, UniMAP Introduction 2 Digital derived from the way computers perform operation by counting digits Applications computers communications systems entertainment medical instruments consumer electronics so much more

School of Computer and Communication Engineering, UniMAP Analogue and Digital 3 Analogue Is a quantity with continuous values Most of the things around us are analogue in nature Eg: temperature, sound, heat, time etc Digital Is a quantity with a discrete set of values consists of logic high “1” and logic low “0” analogue quantity is sampled at certain interval and represented by a digital code.

School of Computer and Communication Engineering, UniMAP Example: Analog 4 Figure 1–1 Graph of an analog quantity (temperature versus time).

School of Computer and Communication Engineering, UniMAP Example: Digital 5 Figure 1–2 Sampled-value representation (quantization) of the analog quantity in Figure 1–1. Each value represented by a dot can be digitized by representing it as a digital code that consists of a series of 1s and 0s.

School of Computer and Communication Engineering, UniMAP Advantages of Digital 6 Can be processed (computer) and transmitted (communications) more efficiently and reliably than analogue can produce greater accuracy and clarity (eg: process that requires storage – CD,DVD) Effective data can retreive Noise (unwanted attribute) does not affect digital data nearly as much as with analog signals

School of Computer and Communication Engineering, UniMAP Example: Basic audio public system 7 Figure 1–3 A basic audio public address system

School of Computer and Communication Engineering, UniMAP Example: Block diagram of CD player 8 Figure 1–4 Basic block diagram of a CD player. Only one channel is shown.

School of Computer and Communication Engineering, UniMAP Binary Digits – Logic Levels – Digital Waveform 9 Binary Digits In binary systems – “1” & “0” is called a bit therefore “1” & “0” is a binary digit In digital circuits; two different voltage values - High voltage = “1” - Low voltage = “0” # This is +ve logic; # -ve logic is the other way round Group of bits; combination of 1s & 0s we called as codes

School of Computer and Communication Engineering, UniMAP Binary Digits – Logic Levels – Digital Waveform 10 Logic Levels The voltages to represent a 1 and a 0 must be a certain values of voltages Figure 1–5 Logic level ranges of voltage for a digital circuit.

School of Computer and Communication Engineering, UniMAP Binary Digits – Logic Levels – Digital Waveform Digital waveform 11 Figure 1–6 Ideal pulses.

School of Computer and Communication Engineering, UniMAP Example: Non-ideal Pulse Characteristics 12 Figure 1–7 Nonideal pulse characteristics

School of Computer and Communication Engineering, UniMAP Waveform Characteristic 13 Most waveform in digital sys composed of series of pulses, called pulse train These pulse train can be: - periodic – repeated at fixed interval - non periodic – not repeated at fixed interval

School of Computer and Communication Engineering, UniMAP Question: 14 Measure: (a)Period T (b) frequency f (c) duty cycle = (tw/T)100%

School of Computer and Communication Engineering, UniMAP The Clock 15 -Is a periodic waveform in which each interval between pulses(period) equals the time for one bit Figure 1–10 Example of a clock waveform synchronized with a waveform representation of a sequence of bits.

School of Computer and Communication Engineering, UniMAP Timing Diagram 16 A graph of digital waveform showing the actual time relationship of two or more waveforms and how each changes in relation to others Figure 1–11 Example of a timing diagram.

School of Computer and Communication Engineering, UniMAP Example: Serial and Parallel 17 Figure 1–12 Illustration of serial and parallel transfer of binary data. Only the data lines are shown.

School of Computer and Communication Engineering, UniMAP Question: 18

School of Computer and Communication Engineering, UniMAP Basic Logic Gate 19 Figure 1–15 The basic logic operations and symbols.

School of Computer and Communication Engineering, UniMAP Not gate (Inverter) 20

School of Computer and Communication Engineering, UniMAP AND gate 21 AND Operation = Produces HIGH (1) output when all input are HIGH

School of Computer and Communication Engineering, UniMAP OR gate 22 OR Operation  Produces HIGH ouput when one or more inputs are HIGH

School of Computer and Communication Engineering, UniMAP Comparator 23 Figure 1–19 The comparison function.

School of Computer and Communication Engineering, UniMAP Adder 24 Figure 1–20 The addition function.

School of Computer and Communication Engineering, UniMAP Encoder 25 Figure 1–21 An encoder used to encode a calculator keystroke into a binary code for storage or for calculation.

School of Computer and Communication Engineering, UniMAP Decoder 26 Figure 1–22 A decoder used to convert a special binary code into a 7-segment decimal readout.

School of Computer and Communication Engineering, UniMAP MUX/DEMUX 27 Figure 1–23 Illustration of a basic multiplexing/demultiplexing application.

School of Computer and Communication Engineering, UniMAP 4-bit Serial Shift Register 28 Figure 1–24 Example of the operation of a 4-bit serial shift register. Each block represents one storage “cell” or flip-flop.

School of Computer and Communication Engineering, UniMAP 4-bit Parallel Shift Register 29 Figure 1–25 Example of the operation of a 4-bit parallel shift register.

School of Computer and Communication Engineering, UniMAP Basic Counter 30 Figure 1–26 Illustration of basic counter operation.

School of Computer and Communication Engineering, UniMAP IC Pin Numbering 31 Figure 1–30 Pin numbering for two standard types of IC packages. Top views are shown.

School of Computer and Communication Engineering, UniMAP 32 Q & A