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Slide02 digital logic operations and functions


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Slide02 digital logic operations and functions

  1. 1. 517212: Digital Logic Designบทที่ 2 - หนาที่และการทำงานของวงจรดิจิทัล 12 พฤศจิกายน 2555
  2. 2. ตัวปฏิบัติการพื้นฐานทางลอจิก ระบบดิจิทัลนั้นสรางจากพื้นฐานทางตรรกศาสตร จอรจ บูล (George Boole) นักคณิตศาสตรชาวอังกฤษไดสรางพีชคณิต เชิงตรรก (Boolean Algebra) ขึ้นมาในชวงทศวรรษที่ 19 ซึ่งภายหลังได นำมาประยุกตใชในการออกแบบและสรางระบบดิจิทัล ตัวปฏิบัติการเชิงตรรกที่ใชเปนพื้นฐานและควรทราบนั้นมีอยูเพียง 3 แบบ ไดแก NOT AND OR
  3. 3. NOTNegationOutput is the opposite of the input, that’s all.The symbol:Note: There is only one input and one output for this op!
  4. 4. ANDThe output will be HIGH only when all the inputs are HIGH.The symbol: Note: there may be more than two inputs.
  5. 5. ORThe output will be HIGH when one or more inputs are HIGH.The symbol:
  6. 6. Basic Logic Functions Roadmap to what we are going to learn: –Comparison function –Arithmetic functions –Code conversion function –Encoding function –Decoding function –Data selection function –Storage function –Counting function
  7. 7. ComparisonA basic comparator compares two quantities and indicates whether or not they are equal. –Think about conditional statement like if or things like that in programming.
  8. 8. Arithmetic Adder is the key-element circuit of binary arithmetic. – You can add (of course, it’s the adder). – You can subtract using adder with special treatment on input number. – You can multiply using adder with the help of other circuits. – You can also divide with series of circuits in conjunction of adder.
  9. 9. Code ConversionA code converter changes one form of coded information into another coded form, i.e.: –binary-to-BCD –binary-to-Gray code –etc.
  10. 10. Encoding and Decoding Encoder converts information, such as a decimal number or an alphabetic character, into some coded form. Decoder does the opposite.
  11. 11. Data Selection Multiplexer (MUX) – Switches digital data from several input lines on a single output line in a special time sequence. Demultiplexer (DEMUX) – Does the opposite.
  12. 12. Storage This function is required in most digital systems. Itcan memorize a bit of a group of bits and retain the information as long as necessary. – Flip-flops – Registers – etc
  13. 13. CountingCounting is one of the most important function in digital systems. –Think about the loop in programming, you cannot accomplish unless you have some sort of counter.To count, the counter must remember the present numbers  it can go to the next proper number in sequence.
  14. 14. Integrated Circuits (ICs)
  15. 15. Fixed-Function ICs design/images/dt_chip.jpg pressrelease/2002/images/dsair.jpg hutchinson/images/c01356.jpg
  16. 16. Complexity Classifications for Fixed-Function ICs Small-scale integration (SSI) – Up to 10 gate circuits Medium-scale integration (MSI) – 10-100 gate circuits Large-scale integration (LSI) – 100-10,000 gates Very large-scale integration (VLSI) – 10,000-100,000 gates Ultra large-scale integration (ULSI) – More than 100,000 gates
  17. 17. Programmable Logic PL devices can be programmed to perform specified logic functions using software. –Hardware Description Language (HDL)A design can be implemented faster and with less cost (small volume). Just remember the name: –Field Programmable Gate Array (FPGA) –Complex Programmable Logic Device (CPLD)
  18. 18. รูป title page