Learn Digital Design of Microcomputer Systems with Deeds


  • Aizat Haikal SCHOOL


Classification of Sequential Logic

As standard logic gates are the building blocks of combinational circuits, bistable latches and flip-flops are the basic building blocks of sequential logic circuits. Sequential logic circuits can be constructed to produce either simple edge-triggered flip-flops or more complex sequential circuits such as storage registers, shift registers, memory devices or counters. Either way sequential logic circuits can be divided into the following three main categories:

  • 1. Event Driven– asynchronous circuits that change state immediately when enabled.
  • 2. Clock Driven– synchronous circuits that are synchronised to a specific clock signal.
  • 3. Pulse Driven– which is a combination of the two that responds to triggering pulses.


    SR Flip-Flop

    The SR flip-flop, also known as a SR Latch, can be considered as one of the most basic sequential logic circuit possible. This simple flip-flop is basically a one-bit memory bistable device that has two inputs, one which will “SET” the device (meaning the output = “1”), and is labelled S and one which will “RESET” the device (meaning the output = “0”), labelled R.

    Then the SR description stands for “Set-Reset”. The reset input resets the flip-flop back to its original state with an output Q that will be either at a logic level “1” or logic “0” depending upon this set/reset condition.

    A basic NAND gate SR flip-flop circuit provides feedback from both of its outputs back to its opposing inputs and is commonly used in memory circuits to store a single data bit. Then the SR flip-flop actually has three inputs, Set, Reset and its current output Q relating to it’s current state or history.

    The term “Flip-flop” relates to the actual operation of the device, as it can be “flipped” into one logic Set state or “flopped” back into the opposing logic Reset state.




Manual Pengguna, (2022). AplikasiPendidikandanRekaBentukElektronikDigital (S. Widyarto, Ed. & Trans.; 1st ed.). International Community Forum (ICF).




How to Cite

Haikal, A. (2022). Learn Digital Design of Microcomputer Systems with Deeds. Proceedings of the Informatics Conference, 8(17). Retrieved from https://ojs.journals.unisel.edu.my/index.php/icf/article/view/240