View source for TX-2

{{Short description|Early transistorized computer}}
{{About|the computer|the Texas district|Texas's 2nd congressional district|the successor to the TX1 London taxicab|TXII}}
{{Computer
| name         = TX-2
| image        = TX-2 mod top.jpg
| caption      = Circuit module from the TX-2
| developer    = MIT [[Lincoln Laboratory]]
| family       = TX
| releasedate  = {{Start date|1958}}
| predecessor  = [[TX-0]]
}}

The [[Massachusetts Institute of Technology|MIT]] [[Lincoln Laboratory]] '''TX-2''' [[computer]] was the successor to the Lincoln [[TX-0]] and was known for its role in advancing both [[artificial intelligence]] and [[human–computer interaction]]. [[Wesley A. Clark]] was the chief architect of the TX-2.<ref name="november">{{cite book |title = Biomedial Computing, Digitizing Life in the United States |author = Joseph November |chapter = The LINC Revolution |page=144 |publisher=The Johns Hopkins University Press |year=2012}}</ref>

== Specifications ==
The TX-2 was a [[transistor]]-based computer using the then-huge amount of 64[[kibi-|K]] [[36-bit computing|36-bit]] [[Word (computer architecture)|word]]s of [[magnetic-core memory]]. The TX-2 became operational in 1958.<ref>{{Cite book|url=https://books.google.com/books?id=4iU-AQAAIAAJ&q=%22TX-2%22+1958|title=Computers and People|date=1961|publisher=Berkeley Enterprises|pages=312|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=K4YlDwAAQBAJ&dq=%22TX-2%22+1958&pg=PA131|title=The Machine in the Ghost: Digitality and Its Consequences|last=Boast|first=Robin|date=2017-03-15|publisher=Reaktion Books|isbn=9781780237879|pages=131–132|language=en}}</ref> Because of its powerful capabilities, [[Ivan Sutherland]]'s revolutionary [[Sketchpad]] program was developed for and ran on the TX-2.<ref>Reilly, Edwin D. (2003) [https://archive.org/details/milestonesincomp0000reil/page/261 ''Milestones in Computer Science and Information Technology''] Greenwood Publishing Group {{ISBN|9781573565219}} pg 261</ref><ref>Kalay, Yehuda E. (2004) [https://books.google.com/books?id=BDboJQJvUq8C&pg=PA66 ''Architecture's New Media: Principles, Theories, and Methods of Computer-aided Design''] MIT Press {{ISBN|9780262112840}} pg 66</ref> One of its key features was the ability to directly interact with the computer through a graphical display.<ref>Naughton, John (1999): A brief history of the future: the origins of the internet, London, p. 71</ref>

The TX-2 had 32 modes of [[Predication_(computer_architecture)|predication]], innovative [[bit manipulation instruction set|bitmanipulation instructions]]  <ref>{{Cite web| title=TX-2 users handbook - Chapter 3: Operation code | url=http://www.bitsavers.org/pdf/mit/tx-2/TX-2_UserHandbook_ch3.pdf | archive-url=https://web.archive.org/web/20061016161023/http://www.bitsavers.org:80/pdf/mit/tx-2/TX-2_UserHandbook_ch3.pdf | archive-date=2006-10-16}}</ref> and is likely one of the very first processors with [[SIMD within a register]], used in Sutherland's Sketchpad:

<blockquote>
...the Lincoln Lab’s TX-2 computer offered instructions that operated on the ALU as either one 36-bit operation, two 18-bit operations, or four 9-bit operations...
Sketchpad did in fact take advantage of these SIMD instructions, despite TX-2 appearing before invention of the term SIMD.<ref>{{Cite web| title=SIMD Computers: Attractive Idea, Many Attempts, No Lasting Successes | url=https://www.engr.colostate.edu/~sudeep/wp-content/uploads/CD7.14-P374493.pdf | archive-url=https://web.archive.org/web/20210422162424/https://www.engr.colostate.edu/~sudeep/wp-content/uploads/CD7.14-P374493.pdf | archive-date=2021-04-22}}</ref>
</blockquote>

The [[compiler]] (today we would say [[Assembly_Language#Assembler|assembler]]) was developed by [[Lawrence Roberts (scientist)|Lawrence Roberts]] while he was studying at the MIT Lincoln Laboratory.<ref>{{Cite thesis |last=Lawrence |first=Roberts G. |date=June 1963 |title=Machine perception of three dimensional solids |url=https://dspace.mit.edu/handle/1721.1/11589 |journal=PhD Thesis |pages=82 |hdl=1721.1/11589 }}</ref>

In 1964 the TX-2 was extended with the APEX [[time-sharing]] system. This included a hardware [[Memory management unit|memory-management unit]] named SPAN which employed [[thin-film memory]].<ref name="Forgie_APEX_paper">{{cite conference |last=Forgie |first=James W. |date= |title=A time- and memory-sharing executive program for quick-response on-line applications |url=https://doi.org/10.1145/1463891.1463956|doi=10.1145/1463891.1463956 |work= |book-title=Proceedings of the November 30—December 1, 1965, Fall Joint Computer Conference, part I |conference=1965 [[Fall Joint Computer Conference]] |location=[[Las Vegas|Las Vegas Nevada]] |publisher=Association for Computing Machinery|pages=599–609 |isbn=978-1-4503-7885-7|access-date=6 October 2025|url-access=subscription }}</ref>

== Relationship with DEC ==
[[Digital Equipment Corporation]] was a [[research spin-off|spin-off]] of the TX-0 and TX-2 projects.  The [[TX-2 Tape System]] was a block addressable 1/2" tape developed for the TX-2 by Tom Stockebrand which evolved into [[LINCtape]] and [[DECtape]].

== Role in creating the Internet ==
Dr. [[Leonard Kleinrock]] developed the mathematical theory of packet networks which he successfully simulated on the TX-2 computer at Lincoln Lab.

== Decommissioning ==

TX-2 was taken out of operation and dismantled in 1977.<ref name=CompEng_dismantling_ref>{{cite book |last1=Bell |first1=C. Gordon |last2=Mudge |first2=J. Craig |last3=McNamara |first3=John E. |date= 1978|title=Computer Engineering: A DEC view of hardware systems design |oclc=1007723296 |url=http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/_Books/Bell-ComputerEngineering.pdf |location= |publisher=Digital Press |isbn=0-932376-00-2 |page=128|quote=TX-2 operated until 1977, when it was dismantled.|access-date=6 October 2025}}</ref>

== References ==
{{reflist}}

== External links ==
*[http://www.bitsavers.org/pdf/mit/tx-2 TX-2 documentation at bitsavers.org]
*[https://www.pcmag.com/news/363724/meet-the-professor-who-was-there-when-the-internet-was-turne Interview with UCLA's Dr. Leonard Kleinrock]
*[https://tx-2.github.io/documentation Extensive documentation on the TX-2]

[[Category:One-of-a-kind computers]]
[[Category:Transistorized computers]]
[[Category:36-bit computers]]
[[Category:SIMD computing]]

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