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PLD

PLD. Programmable Logic Devices. PLD. Replace a large number of standard ICs with a single IC. PLD is an IC that contains large numbers of gates, FFs, and registers that are interconnected on the chip. Many of the connections, however, are fusible links that can be broken. PLD.

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PLD

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  1. PLD Programmable Logic Devices

  2. PLD • Replace a large number of standard ICs with a single IC. • PLD is an IC that contains large numbers of gates, FFs, and registers that are interconnected on the chip. • Many of the connections, however, are fusible links that can be broken.

  3. PLD • IC is said to be programmable because the specific function of the IC for a given application is determined by the selective breaking of some of the interconnections while leaving others intact. • Programming produces the desired circuit pattern interconnecting the gates, FFs, and registers.

  4. PLD • Example of programmable logic device.

  5. PLD • Each input feeds both a noninverting buffer and an inverting buffer to produce the true and inverted forms of each variable. • These are the input lines to the AND gate array. • Each AND gate is connected to two different input lines so as to generate a unique product of the input variables. • The AND outputs are called the product lines. • The PLD can be programmed so that each of the OR outputs to any desired function in a similar manner.

  6. PLD Symbology

  7. Programmable Logic Array (PLA)

  8. Programmable Logic Array (PLA) • Internal construction of a specific PLA.

  9. Programmable Logic Array (PLA) - Example

  10. Example 1: PLA

  11. Example 2: PLA

  12. Exercise: PLA Implement the combinational circuit shown in truth table, using PLA.

  13. Programmable Array Logic (PAL) • Programmable logic device with a fixed OR array and a programmable AND array. • Because only AND gates are programmable, PAL is easier to program. • Developed to overcome certain disadvantages of PLA, such as longer delays due to additional fusible links that result from using two programmable arrays and more circuit complexity.

  14. Programmable Array Logic (PAL)

  15. Programmable Array Logic (PAL)

  16. Programmable Array Logic (PAL)

  17. Programmable Array Logic (PAL)

  18. Programmable Array Logic (PAL)

  19. Programmable Array Logic (PAL)

  20. Example 2: PAL Implement the combinational circuit using PAL.

  21. Generic Array Logic (GAL) • Has reprogrammable AND array and fixed OR array with programmable output logic.

  22. Generic Array Logic (GAL) • GAL operation

  23. Generic Array Logic (GAL) • GAL implementation of SOP expression

  24. Generic Array Logic (GAL) • GAL Block diagram

  25. Generic Array Logic (GAL) • Standard GAL Numbering

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