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  • Introduction to Asynchronous Sequential Circuits

    The essence of understanding asynchronous circuits is to realise that for the circuit to be stable the outputs generated by the input(s) must be equal (i.e. Y=y), since these two sets of signals are connected via the feedback....

    2017/11/22 zhengxiaowei 127

  • Asynchronous and Synchronous Circuits

    In this introductory text we will define two broad classes of sequential circuits, namely; asynchronous and synchronous....

    2017/11/21 zhengxiaowei 130

  • Sequential Logic Circuits: An Overview

    All of the circuits so far considered in this book have been combinational. This means that their outputs are dependent only upon the inputs at that time. We now turn our attention to sequential logic circuits whose outputs are also dependent upon past inputs, and hence outputs....

    2017/11/21 zhengxiaowei 128

  • What is Heuristic implementation

    Heuristic implementations can broadly be considered as those that are not produced by rigorous application of Boolean logic theory. (Remember that any truth table canĀ» in theory, be implemented in fundamental or minimised two-level form.)...

    2017/11/17 zhengxiaowei 163

  • Two-level Circuit Implementation

    Clearly the large number of gates required, the large number of inputs they must possess, and the fact that some signals must feed into many gates, means that this implementation is also impractical, although it is an improvement on the fundamental two-level form....

    2017/11/17 zhengxiaowei 111

  • Combinational Logic Design Example: A Four-Bit Adder

    In this section we consider the design of a four-bit adder; i,e. a circuit that adds together two four-bit binary numbers. This needs to be a combinational logic circuit and therefore serves as a useful exercise to apply what we have learnt....

    2017/11/17 zhengxiaowei 170

  • The Multiplexer as a Universal Logic Solution

    Because all 2m possible combinations of the m control lines of a multiplexer are fed to 2m AND gates then there is an AND gate for all of the fundamental product terms of the m variables....

    2017/11/16 zhengxiaowei 140

  • Common Combinational Logic Circuits

    There are a number of combinational logic circuits which are used so frequently that they are often considered to exist as circuit elements (like logic gates) in their own right. Note that the forms of these circuits given here are those that implement the basic functions....

    2017/11/16 zhengxiaowei 143