- A linear
**tape**consisting of cells stretching without bounds to the left and to the right. The tape can move left (L) or right (R)

- A
**text alphabet**of symbols, e.g., {*b*, 0, 1, X, Y}. The**blank***b*is always the contents of all but a finite number of cells (i.e. those containing data to be processed).

- A
**read/write tape head**that can read and write one tape cell in one step.

- A
**state**that is named by a countable set of numbers 1, 2, ...,*n*for some fixed*n*(though we will generally use letters A ... Z)

- A set of
**instructions**.

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Last Updated 01/05/2000

© L.Heath, 2000