Prof. Dr. Thorsten Jungmann (last updated 2026-10-03)
Edward F. Moore (1925–2003) was an American professor of mathematics and computer science, the inventor of the Moore finite state machine and an early pioneer of artificial life. He received a B.S. in chemistry from the Virginia Polytechnic Institute in 1947 and a Ph.D. in mathematics from Brown University in 1950. He worked at the University of Illinois at Urbana–Champaign in 1950–51 and at Bell Labs from 1951 to 1966, and from 1966 until his retirement in 1985 he was a professor at the University of Wisconsin–Madison. Together with Claude Shannon he did seminal work on computability theory and built reliable circuits using less reliable relays.
The Moore machine (German: Moore-Automat) is named after him. It is a finite state machine whose current output values are determined only by its current state, in contrast to the Mealy machine, whose outputs depend on the current state and on the inputs. The input typically influences the next state, so it can influence later outputs only indirectly, not the current one. In the state diagram of a Moore machine an output value is associated with each state. Moore presented the concept in 1956 in the paper ‘Gedanken-experiments on Sequential Machines’.
Most digital electronic systems are designed as clocked sequential systems, in which the state changes only when the global clock signal changes; they can be built as Moore or as Mealy machines. Typically the current state is stored in flip-flops, and the global clock signal is connected to their clock inputs. In a Moore machine, combinational logic decodes the current state into the outputs, which stay the same until the machine changes state again. Every Moore machine is equivalent to a Mealy machine with the same states and transitions. Conversely, a Mealy machine can be converted into a Moore machine, usually with additional states; its outputs then change one clock cycle later.
Reference and further reading:
https://en.wikipedia.org/wiki/Edward_F._Moore
https://en.wikipedia.org/wiki/Moore_machine
https://en.wikipedia.org/wiki/Mealy_machine