Combinational Circuits Sequential Circuits
Consists of logic gates whose outputs at any time are determined by combining the values of the applied inputs using logical operations.
Combinational Circuit .
Decoders Encoders Counters Half Adder Full Adder
with a number of output lines,
only one of which is asserted at any time
, dependent on the pattern of input lines.
n inputs and 2 n outputs.
1 2 1 = 2 2 2 2 = 4 3 2 3 = 8 Converts binary information from the n coded inputs to a maximum of 2 n unique outputs.
Larger decoders from small decoders with enable inputs.
3-8 line decoder from 2-4 line decoders 6-64 line decoder from 4-16 line decoders
3-to-8-line decoder constructed from two 2 to-4-line decoders The MSB is connected to the enable inputs if A 2 =0, upper is enabled; if A 2 =1, lower is enabled.
Combinational logic circuit which performs reverse of decoder functions.
Accepts an active level on one of its inputs and converts to a coded output.
The process of converting familiar symbols or numbers to a coded format is called encoding.
Highest priority takes precedence.