Topic: computer as state machine

topics > computer science > computer hardware > Group: machine model

Petri net
problems with the von Neumann architecture
state machine
Turing machine
von Neumann computer
what is a computer


A computer is a state machine, or more accurately, behaves as if it were a state machine. Most circuitry is binary. Early computers experimented with decimal and other bases. The idea of state is an abstract interpretation of analog processes.

A state machine is a direct implementation of a Turing machine, and is thus a universal model for programming. While usually too cumbersome as an execution model for large programs, it is an accurate picture of the static description of a program.

This distinction between the computer's behavior and our interpretation of that behavior is an important one. What makes a computer isn't its behavior. What makes a computer is an observer-defined interpretation of how that behavior correlates to numbers and how those numbers correlate to rules, real events and objects. (cbb 4/94)

Subtopic: computers from binary elements up

Quote: digital computers use relay-like elements of two or more states; e.g., neurons which can be imitated by vacuum tubes at 1000x faster [»vonnJ6_1945]
Quote: a computer's arithmetic, control and memory parts should use binary representation; simpler logical structure [»vonnJ6_1945]
Quote: a computing machine is an automatic machine that uses 0 and 1 for input and output [»turiAM11_1936]

Subtopic: state machine up

Quote: a program determines a set of executions, i.e., a sequence of states [»parnDL_1997]
Quote: a true, digital computer is an abstraction; a real computer must be composed of analogue circuits [»wilkVW8_1992]
Quote: discrete state machines move from state to state; don't really exist but still a useful abstraction [»turiAM10_1950]
Quote: a digital device is always in some state; so states partition its existential time and transitions are instantaneous [»holtAW11_1980]
Quote: a computer hardware designer simulates discrete behavior by analog means
Quote: an 'and' gate only works correctly if its inputs do not change; not physically realizable because of missing reaction [»petrCA1_1966, OK]
Quote: the physical state of a computer does not describe the computational process; a computational state is an equivalence class of complex physical states [»pylyZW_1986]

Subtopic: program and data as initial state up

Quote: a program defines the initial conditions of a computer or state machine [»cbb_1973, OK]
Quote: a data object is a number since it is part of the initial state of a computation
Quote: in a digital device, changing a single bit can have drastic consequences; a radical novelty of computers [»dijkEW12_1989]

Subtopic: observer-relative up

Quote: computation and syntax are observer-relative; 0/1 depends on an interpretation [»searJR_1992]
Quote: computers only operate on the marks of numbers; humans set up a correspondence between any set of things and numbers [»jakiSL_1969]
Quote: digital computers allow many representational layers; a variable may represent a satellite and in turn be represented by a voltage [»winoT_1986]
Quote: most computational theories of mind assume a homunculus; even if reduce to 0/1's still need a homunculus to interpret them [»searJR_1992]
Quote: cognitive science can never be a natural science since computation is observer-relative
Quote: representation is in the mind of the beholder; nothing in the computer or program depends on the representation selected [»winoT_1986]
Quote: a mechanical computer does not literally follow rules; it only behaves as if it does

Related Topics up

Topic: Petri net (44 items)
Topic: problems with the von Neumann architecture (11 items)
Topic: rules (43 items)
Topic: state (35 items)
Topic: state machine (67 items)
Topic: Turing machine (30 items)
Topic: von Neumann computer (14 items)
Topic: what is a computer
(62 items)

Updated barberCB 4/04
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Thesa is a trademark of C. Bradford Barber.