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  • Dec 31, 1927
    (b.) -
    Jun 21, 2010
    (d.)

Bio/Description

Designer of the Mealy machine; he presented the concept in a 1955 paper, “A Method for Synthesizing Sequential Circuits”. The Mealy machine is a finite-state machine whose output values are determined both by its current state and the current inputs. (This is in contrast to a Moore machine, whose output values are determined solely by its current state.) A Mealy machine is a deterministic finite state transducer: for each state and input, at most one transition is possible. More complex Mealy machines can have multiple inputs as well as multiple outputs. Mealy machines provide a rudimentary mathematical model for cipher machines. Considering the input and output alphabet the Latin alphabet, for example, then a Mealy machine can be designed that given a string of letters (a sequence of inputs) can process it into a ciphered string (a sequence of outputs). However, although one could use a Mealy model to describe the Enigma, the state diagram would be too complex to provide feasible means of designing complex ciphering machines. He was deeply involved in SOS development at the RAND Corporation and joined IBM for the OS/360 project. He was a co-creator of the initial version of the system BESYS2 (Bell Operating System) with Gwen Hansen and Wanda Lee Mammel under the guidance of Victor A. Vyssotsky. It utilized IBM's FORTRAN and North American's symbolic assembly program (SAP) programming languages. It was an early computing environment originally implemented as a batch processing operating system in 1957 at Bell Labs for the IBM 704 computer. The BESYS2 was designed to efficiently deal with a large number of jobs originating on punched cards and producing results suitable for printing on paper and punched cards. The system also provided processing capabilities for data stored on magnetic tapes and magnetic disk storage units. Typically punched card and print processing was handled off line by peripheral IBM Electronic Accounting Machines, IBM 1401 computers and eventually direct coupled computers.
  • Date of Birth:

    Dec 31, 1927
  • Date of Death:

    Jun 21, 2010
  • Noted For:

    Designer of the Mealy machine; a finite-state machine whose output values are determined both by its current state and the current inputs
  • Category of Achievement:

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