Types of a circuits

1. Combinational - Given a set of inputs the output is going to be the same
2. Sequential - There can be different outputs based on the sequence of inputs

Multiplexer

A combinations circuit with 2^n data inputs, 1 data output and n-bit control input that selects one of the data inputs

A multiplexer works somewhat like a tv channel switcher would work. Used in CPUS

Multiplexers are line train tracks

Decoder

A combinational circuit with n-bit control and 2^n outputs.

–Logical– Bitwise Operations

Bitwise operations are different from logical. Logical operations involve true and and flase

• AND - The result bit is on if the corresponding bits in the operation are both on

     1000 1000
  and  1000 0100
  --------------
     1000 0000
  

• OR - The result bit is on if the corresponding bit in any operand is on

  0101
  1010
or
-------
  1111

Adder

• Half adder makes up a
• full adder

Combinational vs Sequential

Combinational circuits always give the same output for a given set of inputs – ie adder always generates sum and carry regardless of previous input.

Sequential circuits store information, The output is dependent on stored information plus inputs. For example a ticket counter. When a circuit is looping its output back into the circuit then there is a good that it is sequential

States

• the state of a system is a snapshot of it ay any given point in time

  Flips Flops

SR (NAND) Flip flops

When S and R both =1 then