RGPV 2010
Q. Formally define the following (with example)-
1. Mealy machine
2. Moore machine
1. Mealy machine: Mealy machine is a six tuple machine.M = (Q, Σ, △, δ, λ, q0)
- Q is finite set of states.
- Σ is the input alphabet.
- △ is the output alphabet.
- δ is transition function which maps Q×∑ → Q.
- ‘λ’ is the output function which maps Q×∑→ △.
- q0 is the initial state.
Transition table for Mealy machine

Transition diagram for Mealy machine
1. Moore machine: Moore machine is a six tuple machine.M = (Q, Σ, △, δ, λ, q0)
- Q is finite set of states.
- Σ is the input alphabet.
- △ is the output alphabet.
- δ is transition function which maps Q×∑ → Q.
- ‘λ’ is the output function which maps Q → △.
- q0 is the initial state.
Transition table for Moore machine

Transition diagram for Moore machine
Mealy machine vs Moore machine
Mealy machine | Moore machine |
Output depends on present state as well as present input. | Output depends on the present state. |
If input changes, output also changes | If input changes, output does not changes. |
Compare to Moore less number of states are required. Because states do not depends on output. | Compare to Mealy more number of states are required. Because states depends on number of output. |
Difficult to develop. Difficulty due to input affects output. | Easy to develop. |
Output is placed on transition arrow. | Output is placed with state. |
Practice problems: