Analysis Analyze existing circuits to determine their function Synchronous sequential circuit The basic modeling structure Two circuit models: Mealy model& Moore model Three approach used to describe the circuit: Logic function equation

Sequential Circuit Models Yo Combinational logic Universal combinational circuit model No memory units No feedback from logic outputs back to the inputs

Registers, formed from collection of flip -flops, are used to store or manipulate data or both. Input and output function associated with registers include Parallel input/ Parallel output Serial input/ Serial output Parallel input/ Serial output OSerial input parallel output

simple counters Counting is a fundamental function of digital circuits. A digital counter consists of a collection of flip-flops that change states (set or reset) in a prescribed sequence

FLIP-FLOPS Add the certain combinational logic circuit to the input of the original flip- flop New

FLIP-FLOPS Flip-flops are digital devices that have the ability to store binary information after the excitation input has changed. They are considered to be the basic memory cell for the majority of electronic binary data storage applications. This section explores the flip-flop from a functional perspective

Let be the set of all input variables, X={, X1, .Xn} Let y be the set of all output variables, y={Y, 1 ...m} o The combinational function, F, operated on the input variable set, to produce the output variable set y. o The output is related to the input as

Hazard o Boolean algebra does not account for propagation delays through signal paths of actually circuits. o The delay can cause glitches to occur. A glitch is an unwanted signal, usually short pulse caused by the transient behavior of signal path that have different delays A hazard exists any time the potential for glitches is present

INTRODUCTION Level five Complex Systems, Function Units from levels Two through Four Level four More complex Function Logic Units, e.g. microprocessor Third IC level (VLSI) Level three Function Logic Units, e.g. adders, Second IC level counters, multiplexers (MSI and LSI) Level two Function Logic Units, e.g. gates, NOT, AND, NAND, EX-OR First IC level (SSI)

Basie cCoucept Boolean algebra (Logic algebra) is closure mathematical system that defines a series of logic operation (and, or, not) performed on set k of variables (a, b,...) which can only have two values of 0 or 1