Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Digital Fundamentals Tenth Edition Floyd Chapter 1 Floyd, Digital Fundamentals, 10th ed © 2008 Pearson Education Slide 1 Summary Analog Quantities Most natural quantities that we see are analog and vary continuously. Analog systems can generally handle higher power than digital systems. Temperature (°F) 100 95 90 85 80 75 70 Time of day 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 A .M . P.M . Digital systems can process, store, and transmit data more efficiently but can only assign discrete values to each point. Floyd, Digital Fundamentals, 10th ed Slide 2 Summary Analog and Digital Systems Many systems use a mix of analog and digital electronics to take advantage of each technology. A typical CD player accepts digital data from the CD drive and converts it to an analog signal for amplification. CD drive 10110011101 Digital data Digital-to-analog converter Linear amplifier Analog reproduction of music audio signal Speaker Sound waves Floyd, Digital Fundamentals, 10th ed Slide 3 Summary Binary Digits and Logic Levels Digital electronics uses circuits that have two states, which are represented by two different voltage levels called HIGH and LOW. The voltages represent numbers in the binary system. VH(max) In binary, a single number is called a bit (for binary digit). A bit can have the value of either a 0 or a 1, depending on if the voltage is HIGH or LOW. HIGH VH(min) Invalid VL(max) LOW VL(min) Floyd, Digital Fundamentals, 10th ed Slide 4 Summary Digital Waveforms Digital waveforms change between the LOW and HIGH levels. A positive going pulse is one that goes from a normally LOW logic level to a HIGH level and then back again. Digital waveforms are made up of a series of pulses. HIGH HIGH Rising or leading edge LOW Falling or trailing edge t0 (a) Positive–going pulse Floyd, Digital Fundamentals, 10th ed t1 Falling or leading edge LOW Rising or trailing edge t0 t1 (b) Negative–going pulse Slide 5 Summary Pulse Definitions Actual pulses are not ideal but are described by the rise time, fall time, amplitude, and other characteristics. Overshoot Ringing Droop 90% Amplitude tW 50% Pulse width 10% Ringing Base line Floyd, Digital Fundamentals, 10th ed Undershoot tr tf Rise time Fall time Slide 6 Summary Periodic Pulse Waveforms Periodic pulse waveforms are composed of pulses that repeats in a fixed interval called the period. The frequency is the rate it repeats and is measured in hertz. 1 f T 1 T f The clock is a basic timing signal that is an example of a periodic wave. What is the period of a repetitive wave if f = 3.2 GHz? T Floyd, Digital Fundamentals, 10th ed 1 1 313 ps f 3.2 GHz Slide 7 Summary 8 bits = 1 byte 1024 Bytes = 1 KB (kilobyte) 1024 Kilobytes = 1 MB (megabyte) 1024 Megabytes = 1 GB (gigabyte) 1024 Gigabytes = 1 TB (Terabyte) 103 Hz =1 kHz (kilohertz) 106 Hz =1 MHz (megahertz) 109 Hz =1 GHz (gigahertz) 1012 Hz =1 THz (terahertz) A picosecond is 10−12 of a second 10−3 s =1 ms (millisecond) 103 s =1 ks (kilosecond) 10−6 s=1 µs (microsecond) 106 s =1 Ms (megasecond) 10−9 s=1 ns (nanosecond) 109 s =1 Gs (gigasecond) 10−12 s=1 ps (picosecond) 1012 s =1Ts (terasecond) Floyd, Digital Fundamentals, 10th ed Slide 8 Summary Pulse Definitions In addition to frequency and period, repetitive pulse waveforms are described by the amplitude (A), pulse width (tW) and duty cycle. Duty cycle is the ratio of tW to T. Volts Amplitude (A) Pulse width (tW) Time Period, T Floyd, Digital Fundamentals, 10th ed Slide 9 Summary Timing Diagrams A timing diagram is used to show the relationship between two or more digital waveforms, Clock A B C Floyd, Digital Fundamentals, 10th ed Slide 10 Summary Serial and Parallel Data Data can be transmitted by either serial transfer or parallel transfer. 1 t0 0 t1 1 t2 1 t3 0 0 t 4 t 5 t6 1 0 t7 Computer Modem 1 Computer Printer 0 1 1 0 0 1 0 t0 Floyd, Digital Fundamentals, 10th ed t1 Slide 11 Summary Basic Logic Functions True only if all input conditions are true. True only if one or more input conditions are true. Indicates the opposite condition. Floyd, Digital Fundamentals, 10th ed Slide 12 Summary Basic System Functions And, or, and not elements can be combined to form various logic functions. A few examples are: The comparison function A Comparator A> B Two binary numbers A= B B A< B Basic arithmetic functions Adder A Two binary numbers B Carry in Floyd, Digital Fundamentals, 10th ed Outputs Σ Cout Sum Carry out Cin Slide 13 Summary Basic System Functions HIGH The encoding function 7 4 8 1 2 3 0 . +/– 5 9 6 9 8 7 6 5 4 3 2 1 0 Encoder Binary code for 9 used for storage and/or computation Calculator keypad The decoding function Decoder Binary input 7-segment display Floyd, Digital Fundamentals, 10th ed Slide 14 Summary Basic System Functions The data selection function Multiplexer A ∆t1 B Demultiplexer Data from A to D Data from B to E Data from C to F Data from A to D ∆ t1 ∆ t2 ∆ t3 ∆t 1 D ∆t1 E ∆t2 C Floyd, Digital Fundamentals, 10th ed ∆t2 ∆t3 ∆t3 Switching sequence control input Switching sequence control input F Slide 15 Summary Basic System Functions The counting function Counter 1 2 3 4 Input pulses 5 Parallel output lines Binary code for 1 Binary code for 2 Binary code for 3 Binary code for 4 Binary code for 5 Sequence of binary codes that represent the number of input pulses counted. …and other functions such as code conversion and storage. Floyd, Digital Fundamentals, 10th ed Slide 16 Summary Basic System Functions One type of storage function is the shift register, that moves and stores data each time it is clocked. Serial bits on input line 0101 010 01 0 0 0 0 0 1 0 0 0 0 1 0 0 1 0 1 0 0 1 0 1 Floyd, Digital Fundamentals, 10th ed Initially, the register contains onlyinvalid data or all zeros as shown here. First bit (1) is shifted serially into the register. Second bit (0) is shifted serially into register and first bit is shifted right. Third bit (1) is shifted into register and the first and second bits are shifted right. Fourth bit (0) is shifted into register and the first, second, and third bits are shifted right. The register now stores all four bits and is full. Slide 17 Summary Integrated Circuits Cutaway view of DIP (Dual-In-line Pins) chip: Chip Plastic case Pins The TTL series, available as DIPs are popular for laboratory experiments with logic. Floyd, Digital Fundamentals, 10th ed Slide 18 Summary Integrated Circuits An example of laboratory prototyping is shown. The circuit is wired using DIP chips and tested. DIP chips In this case, testing can be done by a computer connected to the system. Floyd, Digital Fundamentals, 10th ed Slide 19 Summary Integrated Circuits DIP chips and surface mount chips Pin 1 Dual in-line package Floyd, Digital Fundamentals, 10th ed Small outline IC (SOIC) Slide 20