Editing Stored-program computer (section)

===Telecommunication===
The concept of using a stored-program computer for switching of telecommunication circuits is called [[stored program control]] (SPC). It was instrumental to the development of the first [[electronic switching system]]s by [[American Telephone and Telegraph]] (AT&T) in the [[Bell System]],<ref>{{cite book |first1=D.H. |last1=Carbaugh |first2=N.L. |last2=Marselos |chapter=Switching System Software |title=Fundamentals of Digital Switching Systems |editor1-first=J. C. |editor1-last=McDonald |publisher=[[Plenum Press]] |date=1983 |isbn=0-306-41224-1}}</ref> a development that started in earnest by c. 1954 with initial concept designs by [[Erna Schneider Hoover]] at [[Bell Labs]]. The first of such systems was installed on a trial basis in [[Morris, Illinois]] in 1960.<ref>{{cite journal |last1=Joel |first1=A. E. |title=An Experimental Electronic Switching System |journal=[[Bell Laboratories Record]] |date=October 1958 |volume=36 |issue=10 |pages=359–363 |url=https://worldradiohistory.com/Archive-Bell-Laboratories-Record/50s/Bell-Laboratories-Record-1958-10.pdf#page=5 |access-date=13 October 2022}}</ref> The storage medium for the program instructions was the [[flying-spot store]], a [[photographic plate]] read by an optical scanner that had a speed of about one microsecond access time.<ref>{{cite magazine |title=Electronic Central Office |magazine=Long Lines |volume=40 |issue=5 |page=16 |date=December 1960 |url=https://www.telephonecollectors.info/index.php/browse/document-repository/catalogs-manuals/bell-system-we/pubs-docs/12290-60dec-longlines-att-r/file}}</ref> For temporary data, the system used a barrier-grid electrostatic [[storage tube]].