“The machine may also change the square which is being scanned, but only by shifting it one place to right or left.”

However, by altering its m-configuration the machine can effectively remember some of the symbols which it has "seen" (scanned) previously.
On Computable Numbers, with an Application to the Entscheidungsproblem (1936)

Source: Killing History: The False Left-Right Political Spectrum and the Battle between the ‘Free Left’ and the ‘Statist Left', (2019), pp. 194-195

The Mythical Man-Month: Essays on Software Engineering (1975, 1995)

Source: Catch-22

Knowing Yourself: The True in the False (1996)

Source: An Introduction to Cybernetics (1956), Part I: Mechanism, p. 9: Chapter 2 Change, lead paragraph.
Context: The most fundamental concept in cybernetics is that of "difference", either that two things are recognisably different or that one thing has changed with time. Its range of application need not be described now, for the subsequent chapters will illustrate the range abundantly. All the changes that may occur with time are naturally included, for when plants grow and planets age and machines move some change from one state to another is implicit. So our first task will be to develop this concept of "change", not only making it more precise but making it richer, converting it to a form that experience has shown to be necessary if significant developments are to be made.

Part 1.3 Rights of Man
1790s, Rights of Man, Part I (1791)

Tales of a Traveler (1824), Preface, p. 7.
Source: Tales of a Traveller