View source for Bell 101

{{Short description|Commercial modem}}
[[File:Teletype-Bell-101C.jpg|thumb|right|The back of a [[Teletype Model 33]] [[teleprinter]] with a Bell 101C Data Set in the pedestal, 1963.]]

The '''Bell 101 Data Set''' was the first commercial [[modem]] for [[computers]], released by [[AT&T Corporation]] in 1958 for use by [[Semi Automatic Ground Environment|SAGE]], and made commercially available in 1959, shortly after AT&T's [[Bell Labs]] announced their 110 baud modulation frequencies.<ref name=connect/><ref name=Bell/> The Bell 101 allowed [[Digital data|digital]] [[data]] to be transmitted over regular unconditioned telephone lines at a speed of 110 [[bits per second]].

The Bell 101 modem used [[audio frequency-shift keying]] to encode data.  Different pairs of audio frequencies were used by each station:<ref name=Manual/>

* The '''originating''' station used a mark tone of 1,270 [[Hertz|Hz]] and a space tone of 1,070&nbsp;Hz.
* The '''answering''' station used a mark tone of 2,225&nbsp;Hz and a space tone of 2,025&nbsp;Hz.

Bell 101 modems are no longer in use and were quickly replaced by its successor the [[Bell 103 modem]]. SAGE modems were described by AT&T's Bell Labs as conforming to the Bell 101 data set standard.

==See also==
* [[List of interface bit rates]]
* [[Bell 202]]

==References==
{{Reflist |refs=
<ref name=connect>{{Cite news |url=https://www.techradar.com/news/internet/getting-connected-a-history-of-modems-657479 |title=Getting connected: a history of modems |work=TechRadar |access-date=2017-07-01 |language=en}}</ref>
<ref name=Bell>{{Cite news |url=https://ethw.org/Bell_Telephone_Laboratories,_Inc._List_of_Significant_Innovations_%26_Discoveries_(1925-1983) |title=Bell Telephone Laboratories, Inc. List of Significant Innovations & Discoveries (1925-1983) |access-date=2017-07-01 |language=en}}</ref>
<ref name=Manual>{{cite work |author=<!--Staff writer(s); no by-line.--> |date=March 1963 |title=Data Set 101C: Identification and Operation |url=https://ed-thelen.org/comp-hist/data_set_101c.pdf |location= |publisher=AT&T Co. |series=Bell System Practices |issue=2 }}</ref>
}}

==Further reading==
* {{cite journal |doi=10.1109/TCE.1959.6372907|title=A frequency-modulation digital subset for data transmission over telephone lines |year=1959 |last1=Weber |first1=Laurance A. |journal=Transactions of the American Institute of Electrical Engineers, Part I: Communication and Electronics |volume=77 |issue=6 |pages=867–872 |s2cid=51673551 }}
* {{cite journal | last1 = Soffel | first1 = R. O. | last2 = Spack | first2 = E. G. | title = SAGE data terminals | journal = Transactions of the American Institute of Electrical Engineers, Part I: Communication and Electronics | date = 1959 | volume = 77 | issue = 6 | pages = 872–879 | issn = 0097-2452 | doi = 10.1109/TCE.1959.6372908 | pmid = | s2cid = 51676153 | url = }}
* {{cite work |author=<!--Staff writer(s); no by-line.--> |date=March 1963 |title=Data Set 101C: Identification and Operation |url=https://ed-thelen.org/comp-hist/data_set_101c.pdf |location= |publisher=AT&T Co. |series=Bell System Practices |issue=2 }}
* {{cite book |doi=10.1007/978-3-030-18955-6_3|chapter=The Modem that Still Connects Us |title=Historical Studies in Computing, Information, and Society |series=History of Computing |year=2019 |last1=Kline |first1=Ronald R. |pages=29–50 |isbn=978-3-030-18954-9 |s2cid=213434332 }}

{{Digital modes}}

{{DEFAULTSORT:Bell 101 Modem}}
[[Category:Modems]]
[[Category:AT&T]]
[[Category:Computer-related introductions in 1959]]
[[Category:Telecommunications-related introductions in 1959]]
[[Category:Bell System modem standards]]

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