Mealy vs Moore machine
The main difference between Mealy and Moore machines lies in how you get the output. In a Mealy machine, the output depends on both the current state and the current input. But in a Moore machine, the output depends only on the current state, no matter what the input is. This affects how fast you see changes in output and how well the output lines up with the clock. You can think of Moore machines as finite state machines where the output depends only on the present state. On the other hand, in Mealy machines, the output depends on both the present state and the current input symbol.
Difference Between Mealy and Moore Machines
| Parameters | Mealy Machine | Moore Machine |
|---|---|---|
| Definition | Changes its output based on the present state and current input. | Output depends only on the current state, not on the current input. |
| Output | Places output on the transition. | Also places output on the transition. |
| States | Has comparatively fewer or the same states as the Moore machine. | Has comparatively fewer or the same states as the Mealy machine. |
| Value of Output Function | The output function becomes a function of transitions and changes when input logic is done in the present state. | The output function’s value becomes a function of the current state along with changes at the edges of the clock when a state change occurs. |
| Reaction to Inputs | Reacts comparatively faster to inputs, usually in the same clock cycle. | Requires more logic for decoding output, resulting in more delays in the circuit. Typically reacts after one clock cycle. |
| State and Output | The asynchronous generation of output through its state alters to synchronous on the present clock. | Both state and output change synchronously with its clock edge. |
| Requirement of States | Generally requires only a very few states for the process of synthesis. | Requires more states for synthesis compared to Mealy machine. |
| Requirement of Hardware | Requires very little hardware for designing. | Requires more hardware for designing. |
| Counter | Cannot be referred to as a Mealy Machine. | Can be referred to as a Moore Machine. |
| Design | The designing process may not be very easy. | The designing process is relatively easy. |
