Editing Turing machine (section)

===Physical description===
In his 1948 essay, "Intelligent Machinery", Turing wrote that his machine consists of:

{{blockquote|...an unlimited memory capacity obtained in the form of an infinite tape marked out into squares, on each of which a symbol could be printed. At any moment there is one symbol in the machine; it is called the scanned symbol. The machine can alter the scanned symbol, and its behavior is in part determined by that symbol, but the symbols on the tape elsewhere do not affect the behavior of the machine. However, the tape can be moved back and forth through the machine, this being one of the elementary operations of the machine. Any symbol on the tape may therefore eventually have an innings.<ref>See the definition of "[[wikt:innings|innings]]" on [[Wiktionary]]</ref>|Turing 1948, p. 3<ref>
{{cite report
| title=Intelligent Machinery
| author=A.M. Turing
| date= Jul 1948
| url=http://www.alanturing.net/Turing_archive/archive/l/l32/L32-004.html
| institution=National Physical Laboratory
}} Here: p.3-4
</ref>}}