Bài giảng Digital System - Chapter 1 -Tran Ngoc Thinh

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1. dce dce 2007 2007 Digital System – Instructor: Assoc. Prof. Dr. Tran Ngoc Thinh Tran Ngoc Thinh • Email: tnthinh@cse.hcmut.edu.vn BK BK TP.HCM HCMC University of Technology TP.HCM • Phone: 38647256 (5843) • Office: A3 building, CE Department • Office hours: Mondays, 09:00-11:00 2 dce dce 2015 Administrative Issues 2015 Administrative Issues (cont.) • Class – Time and venue: Fridays, 15:05 - 17:30, 407A4 • Grades – Web page: – 20% Lab • – 20% assignments/quizzes + presentation – Textbook: • [1] “Digital Systems - 8th Edition” - Ronald J. Tocci, Prentice-Hall 2001 – 30% midterm • [2] “Digital Logic Design Principles”– N. Balabanian, B. Carlson, John Wiley & Sons, Inc , 2004 – 30% final exam • [3] “Digital Design -3rd Edition”–John F. Wakerly, Prentice- Hall 2001 • [4] “Fundamentals of Digital Logic – 2nd edition” – Stephen Brown, Zvonko Vranesic, McGraw Hill 2008 3 4 1
2. dce dce 2015 Course Outline – Part III 2015 Course Outline – Part IV • Flip-Flops and Related Devices • Operation and Circuits – Latches, D Latch – Representing Signed Numbers – Addition, Subtraction in the 2’s-Complement System – Clock Signals and Clocked Flip-Flops – Multiplication, Division of Binary Numbers – S-C, J-K, D Master/Slave Flip-Flops – BCD Addition – Flip-Flop Application – Hexadecimal Arithmetic • Detecting an Input Sequence – Arithmetic Circuits • Data Storage and Transfer • Parallel Binary Adder • Serial Data Transfer: Shift Registers • Design of a Full Adder • Frequency Division and Counting • Carry Propagation • Microcomputer Application • Integrated Circuit Parallel Adder – Schmitt-Trigger, On-shot Devices – 2’s Complement System – Analyzing Sequential & Clock Generator Circuits – BCD Adder – Troubleshooting Flip-Flop Circuits – ALU Integrated Circuits 9 10 dce dce 2015 Course Outline – Part V 2015 Course Outline – Part VI • Counters and Registers – Asynchronous & Synchronous Counters • MSI Logic Circuits – Decoders – Up/Down Counters – Encoders – Cascading BCD Counters – Multiplexers – Synchronous Counter Design – Demultiplexers – Shift-Register Counters – Counter Application: Frequency Counter, Digital Clock – Integrated-Circuit Registers – Some ICs: • Parallel In/Parallel Out – The 74ALS174/HC174 • Serial In/Serial Out – The 4731B • Parallel In/Serial Out – The 74ALS185/HC165 • Serial In/Parallel Out – The 74ALS164/HC164 11 12 3
3. dce dce 2015 Digital and Analog Systems 2015 Digital and Analog Systems • There are limits to digital techniques: • Analog-to-digital conversion (ADC) and – The world is analog digital-to-analog conversion (DAC) complicate circuitry. – The analog nature of the world requires a time consuming conversion process: 1. Convert the physical variable to an electrical signal (analog). 2. Convert the analog signal to digital form. 3. Process (operate on) the digital information 4. Convert the digital output back to real-world analog form. 17 18 dce dce 2015 Digital and Analog Systems 2015 Digital Number Systems • The audio CD is a typical hybrid (combination) • Number systems differ in the number of symbols system. they use – Analog sound is converted into analog voltage. – Decimal – 10 symbols (base 10) – Analog voltage is changed into digital through an – Hexadecimal – 16 symbols (base 16) ADC in the recorder. – Digital information is stored on the CD . – Octal – 8 symbols (base 8) – At playback the digital information is changed into – Binary – 2 symbols (base 2) analog by a DAC in the CD player. • Generalized form of number system base b – The analog voltage is amplified and used to drive a speaker that produces the original analog sound. 19 20 5
4. dce dce 2015 Digital Number Systems 2015 Representing Binary Quantities • Binary Counting • Open and closed switches • Paper Tape 25 26 dce dce 2015 Representing Binary Quantities 2015 Representing Binary Quantities • Other two state devices: • Exact voltage level is not important in digital – Light bulb (off or on) systems. – Diode (conducting or not conducting) • A voltage of 3.6 V will mean the same (binary 1) as a voltage of 4.3 V. – Relay (energized or not energized) – Transistor (cutoff or saturation) – Photocell (illuminated or dark) 27 28 7
5. dce dce 2015 Memory 2015 Digital Computers • A circuit which retains a response to a • Computer – a system of hardware that momentary input is displaying memory. performs arithmetic operations, • Memory is important because it provides a way manipulates data (usually in binary form), to store binary numbers temporarily or and makes decisions. permanently. • Computers perform operations based on • Memory elements include: – Magnetic instructions in the form of a program at – Optical high speed and with a high degree of – Electronic latching circuits accuracy. 33 34 dce dce 2015 Block diagram of digital computer 2015 Digital Computers • Major parts of a computer – Input unit – processes instructions and data into the memory. – Memory unit – stores data and instructions. – Control unit – interprets instructions and sends appropriate signals to other units as instructed. – Arithmetic/logic unit – arithmetic calculations and logical decisions are performed. – Output unit – presents information from the memory to the operator or process. – The control and arithmetic/logic units are often treated as one and called the central processing unit (CPU) 35 36 9
6. dce dce 2015 Decimal to Binary Conversion 2015 Decimal to Binary Conversion • Repeated division steps: • Reverse process described above – Divide the decimal number by 2 – Note that all positions must be accounted for – Write the remainder after each division until a quotient of zero is obtained. – The first remainder is the LSB and the last is the MSB 5 2 0 3710 2 0 0 2 0 2 1 0 12 41 42 dce dce 2015 Decimal to Binary Conversion 2015 Hexadecimal Number System • Repeated division – • Most digital systems deal with groups of bits in This flowchart even powers of 2 such as 8, 16, 32, and 64 bits. describes the • Hexadecimal uses groups of 4 bits. process and can be • Base 16 used to convert from – 16 possible symbols decimal to any other – 0-9 and A-F number system. • Allows for convenient handling of long binary strings. 43 44 11
7. dce dce 2015 Hexadecimal Number System 2015 Number Systems Conversion • Hexadecimal is useful for representing long strings of bits. • Understanding the conversion process and memorizing the 4 bit patterns for each hexadecimal digit will prove valuable later. 49 50 dce dce 2015 BCD 2015 BCD • Binary Coded Decimal (BCD) is another way to present decimal numbers in binary form. • To convert the number 87410 to BCD: • BCD is widely used and combines features of both decimal and binary systems. 8 7 4 • Each digit is converted to a binary equivalent. 0100 0111 0100 = 010001110100BCD • Each decimal digit is represented using 4 bits. • Each 4-bit group can never be greater than 9. • Reverse the process to convert BCD to decimal. 51 52 13
8. dce dce 2015 The Byte, Nibble, and Word 2015 Alphanumeric Codes • 1 byte = 8 bits • Represents characters and functions found on a • 1 nibble = 4 bits computer keyboard. • ASCII – American Standard Code for • 1 word = size depends on data pathway Information Interchange. size. – Seven bit code: 27 = 128 possible code groups – Word size in a simple system may be one – Examples of use are: to transfer information between byte (8 bits) computers, between computers and printers, and for internal storage. – Word size in a PC is eight bytes (64 bits) 57 58 dce dce 2015 Parity Method for Error Detection 2015 Parity Method for Error Detection • Binary data and codes are frequently moved • The parity method of error detection between locations. For example: requires the addition of an extra bit to a – Digitized voice over a microwave link. – Storage and retrieval of data from magnetic and code group. optical disks. • This extra bit is called the parity bit. – Communication between computer systems over telephone lines using a modem. • The bit can be either a 0 or 1, depending • Electrical noise can cause errors during on the number of 1s in the code group. transmission. • There are two methods, even and odd. • Many digital systems employ methods for error detection (and sometimes correction). 59 60 15