Diving Deep into the Dissimilarities Between Mealy Machine and Moore Machine

This article will shed light on the primary distinctions between the Mealy machine and the Moore machine. But first, let's understand what each machine does individually.

An Overview of the Mealy Machine

In the realm of computation theory, a Mealy Machine is recognized as a finite-state machine. The output values of a Mealy machine are determined by its current state and inputs.

A Mealy machine can be represented by a 6 tuple: Q, δ, Ʃ, O, X, q0, where:

• q0 – This is the starting state from where the user can process any input (q0 ϵQ).
• X – This is the output transition function, denoted by X:Q x Ʃ―>O.
• δ – This is the input transition function, represented by δ:Q x Ʃ ―>Q.
• Ʃ – This is a finite set of symbols, also known as the input alphabets.
• O – This is a finite set of symbols, also referred to as the output alphabets.
• Q – This is a finite set of states.

Key Features of a Mealy Machine:

• A Mealy machine has fewer states than a Moore machine.
• The Mealy machine changes its output based on its current state and input.
• Its output is placed on the transition.
• A Mealy machine responds to inputs faster, usually within the same clock cycle.
• The output function's value changes when the input logic is processed in the current state.
• A Mealy Machine typically requires fewer states for the synthesis process.
• The asynchronous output becomes synchronous with the current clock when the state changes.
• Designing a Mealy Machine requires minimal hardware.
• The design process can be complex.
• A counter cannot be classified as a Mealy Machine.

Understanding the Moore Machine

In computation theory, a Moore Machine is another type of finite-state machine. However, the output values in a Moore Machine are determined by its current state alone.

A Moore Machine can be represented by a 6 tuple: Q, δ, Ʃ, O, X, q0, where:

• q0 – This is the starting state from where the user can process any input (q0 ϵQ).
• X – This is the output transition function, denoted by X:Q x Ʃ―>O.
• δ – This is the input transition function, represented by δ:Q x Ʃ ―>Q.
• Ʃ – This is a finite set of symbols, also known as the input alphabets.
• O – This is a finite set of symbols, also referred to as the output alphabets.
• Q – This is a finite set of states.

Key Features of a Moore Machine:

• A Moore Machine has more states than a Mealy Machine.
• Its output is determined solely by its current state and not the current input.
• Its output is placed on the transition.
• The output function's value changes when the state changes, along with clock edge changes.
• Both the state and output change synchronously with the clock edge.
• A Moore Machine requires additional logic for output decoding, resulting in more circuit delays. It typically reacts after one clock cycle.
• Designing a Moore Machine requires more hardware.
• More states are needed for the synthesis process.
• It is relatively easy to design.
• A counter can be classified as a Moore Machine.

Comparing the Mealy Machine and Moore Machine

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