Editing History of computing hardware (section)

==Transistor computers==
{{Main|Transistor computer}}
{{Further|List of transistorized computers}}
[[File:Transistor-die-KSY34.jpg|thumb|left|A [[bipolar junction transistor]] ]]
The bipolar [[transistor]] was invented in 1947. From 1955 onward transistors replaced [[vacuum tube]]s in computer designs,{{sfn|Feynman|Leighton|Sands|1966|pp=14–11 to 14–12}} giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Silicon junction transistors were much more reliable than vacuum tubes and had longer service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space. Transistors greatly reduced computers' size, initial cost, and [[operating cost]]. Typically, second-generation computers were composed of large numbers of [[printed circuit board]]s such as the [[Standard Modular System|IBM Standard Modular System]],{{sfn|IBM|1960}} each carrying one to four [[logic gate]]s or [[Flip-flop (electronics)|flip-flops]].

At the [[University of Manchester]], a team under the leadership of [[Tom Kilburn]] designed and built a machine using the newly developed [[transistor]]s instead of valves. Initially the only devices available were [[germanium]] [[point-contact transistor]]s, less reliable than the valves they replaced but which consumed far less power.{{sfn|Lavington|1998|pp=34–35}} Their first [[transistor computer|transistorized computer]], and the first in the world, was [[Manchester computers#Transistor Computer|operational by 1953]],{{sfn|Lavington|1998|p=37}} and a second version was completed there in April 1955.{{sfn|Lavington|1998|p=37}} The 1955 version used 200 transistors, 1,300 [[Solid-state electronics|solid-state]] [[diode]]s, and had a power consumption of 150 watts. However, the machine did make use of valves to generate its 125&nbsp;kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer.

That distinction goes to the [[Harwell CADET]] of 1955,<ref name="ieeexplore.ieee"/> built by the electronics division of the [[Atomic Energy Research Establishment]] at [[Harwell, Oxfordshire|Harwell]]. The design featured a 64-kilobyte magnetic drum memory store with multiple moving heads that had been designed at the [[National Physical Laboratory (United Kingdom)|National Physical Laboratory, UK]]. By 1953 this team had transistor circuits operating to read and write on a smaller magnetic drum from the [[Royal Radar Establishment]]. The machine used a low clock speed of only 58&nbsp;kHz to avoid having to use any valves to generate the clock waveforms.<ref>{{cite book |last=Cooke-Yarborough |first=E.H. |title=Introduction to Transistor Circuits |publisher=Oliver and Boyd |year=1957 |location=Edinburgh}}</ref><ref name="ieeexplore.ieee">{{cite journal| title=Some early transistor applications in the UK| journal=Engineering Science & Education Journal| volume=7| issue=3| pages=100–106| year=1998| last1=Cooke-Yarborough| first1=E.H.| doi=10.1049/esej:19980301| doi-broken-date=7 December 2024}}</ref>

CADET used 324-point-contact transistors provided by the UK company [[Standard Telephones and Cables]]; 76 [[Bipolar junction transistor|junction transistor]]s were used for the first stage amplifiers for data read from the drum, since point-contact transistors were too noisy. From August 1956, CADET was offering a regular computing service, during which it often executed continuous computing runs of 80 hours or more.<ref>{{cite book |last=Lavington |first=Simon |title=Early British Computers |publisher=Manchester University Press |year=1980 |url=https://ed-thelen.org/comp-hist/EarlyBritish-05-12.html#Ch-09 |isbn=0-7190-0803-4 |access-date=2014-01-07 |archive-date=2019-05-24 |archive-url=https://web.archive.org/web/20190524164254/http://ed-thelen.org/comp-hist/EarlyBritish-05-12.html#Ch-09 |url-status=live }}</ref><ref>{{Cite journal |doi= 10.1049/pi-b-1.1956.0076 |title=A transistor digital computer |journal=Proceedings of the IEE - Part B: Radio and Electronic Engineering |volume=103 |issue=3S |pages=364–370 |year=1956 |last1=Cooke-Yarborough |first1=E.H. |last2= Barnes |first2=R.C.M. |last3=Stephen |first3=J.H. |last4=Howells |first4=G.A.}}</ref> Problems with the reliability of early batches of point contact and alloyed junction transistors meant that the machine's [[mean time between failures]] was about 90&nbsp;minutes, but this improved once the more reliable [[bipolar junction transistor]]s became available.{{sfn|Lavington|1998|pp=36–37}}

The Manchester University Transistor Computer's design was adopted by the local engineering firm of [[Metropolitan-Vickers]] in their [[Metrovick 950]], the first commercial transistor computer anywhere.<ref>{{cite web |title=Metrovick |website=Exposuremeters.net |url= http://www.myphotoweb.com/expmeters/pages/metrovick.htm |url-status=dead |archive-date=2014-01-07 |archive-url=https://web.archive.org/web/20140107164654/http://www.myphotoweb.com/expmeters/pages/metrovick.htm}}</ref> Six Metrovick 950s were built, the first completed in 1956. They were successfully deployed within various departments of the company and were in use for about five years.{{sfn|Lavington|1998|p=37}} A second generation computer, the [[IBM 1401]], captured about one third of the world market. IBM installed more than ten thousand 1401s between 1960 and 1964.

===Transistor peripherals===
Transistorized electronics improved not only the CPU (Central Processing Unit), but also the [[peripheral|peripheral devices]]. The second generation [[disk storage|disk data storage units]] were able to store tens of millions of letters and digits.  Next to the [[fixed disk]] storage units, connected to the CPU via high-speed data transmission, were removable disk data storage units. A removable [[disk pack]] can be easily exchanged with another pack in a few seconds. Even if the removable disks' capacity is smaller than fixed disks, their interchangeability guarantees a nearly unlimited quantity of data close at hand. [[Magnetic-tape data storage|Magnetic tape]] provided archival capability for this data, at a lower cost than disk.

Many second-generation CPUs delegated peripheral device communications to a secondary processor. For example, while the communication processor controlled [[Unit record equipment|card reading and punching]], the main CPU executed calculations and binary [[branch (computer science)|branch instructions]]. One [[Bus (computing)|databus]] would bear data between the main CPU and core memory at the CPU's [[fetch-execute cycle]] rate, and other databusses would typically serve the peripheral devices. On the [[PDP-1]], the core memory's cycle time was 5 microseconds; consequently most arithmetic instructions took 10 microseconds (100,000 operations per second) because most operations took at least two memory cycles; one for the instruction, one for the [[operand]] data fetch.

During the second generation [[Remote Digital Terminal|remote terminal]] units (often in the form of [[Teleprinter]]s like a [[Friden Flexowriter]]) saw greatly increased use.{{efn|[[Allen Newell]] used remote terminals to communicate cross-country with the [[RAND]] computers.{{sfn|Simon|1991}}}} Telephone connections provided sufficient speed for early remote terminals and allowed hundreds of kilometers separation between remote-terminals and the computing center. Eventually these stand-alone computer networks would be generalized into an interconnected ''[[history of the Internet|network of networks]]''—the Internet.{{efn|[[Robert Taylor (computer scientist)|Bob Taylor]] conceived of a generalized protocol to link together multiple networks to be viewed as a single session regardless of the specific network: "Wait a minute. Why not just have one terminal, and it connects to anything you want it to be connected to? And, hence, the Arpanet was born."{{sfn|Mayo|Newcomb|2008}}}}

===Transistor supercomputers===
[[File:University of Manchester Atlas, January 1963.JPG|thumb|The University of Manchester Atlas in January 1963]]
The early 1960s saw the advent of [[Supercomputer|supercomputing]]. The [[Atlas (computer)|Atlas]] was a joint development between the [[Victoria University of Manchester|University of Manchester]], [[Ferranti]], and [[Plessey]], and was first installed at Manchester University and officially commissioned in 1962 as one of the world's first [[supercomputer]]s – considered to be the most powerful computer in the world at that time.{{sfn|Lavington|1998|p=41}} It was said that whenever Atlas went offline half of the United Kingdom's computer capacity was lost.{{sfn|Lavington|1998|pp=44–45}} It was a second-generation machine, using [[Discrete device|discrete]] [[Bipolar junction transistor#Germanium transistors|germanium]] [[transistor]]s. Atlas also pioneered the [[Atlas Supervisor]], "considered by many to be the first recognisable modern [[operating system]]".{{sfn|Lavington|1998|pp=50–52}}

In the US, a series of computers at [[Control Data Corporation]] (CDC) were designed by [[Seymour Cray]] to use innovative designs and parallelism to achieve superior computational peak performance.<ref name=chen>{{cite book |title=Hardware software co-design of a multimedia SOC platform |author1=Sao-Jie Chen |author2=Guang-Huei Lin |author3=Pao-Ann Hsiung |author4=Yu-Hen Hu |year=2009 |pages=70–72}}</ref> The [[CDC 6600]], released in 1964, is generally considered the first supercomputer.<ref>{{cite book |title=History of computing in education |first1=John |last1=Impagliazzo |first2=John A. N. |last2=Lee |year=2004 |isbn=1-4020-8135-9 |page=172 |publisher=Springer |url= https://books.google.com/books?id=J46GinHakmkC&pg=PA172 |access-date=2016-06-04 |archive-date=2023-02-02 |archive-url=https://web.archive.org/web/20230202181649/https://books.google.com/books?id=J46GinHakmkC&pg=PA172 |url-status=live}}</ref><ref>{{cite book |title=The American Midwest: an interpretive encyclopedia |first1=Richard |last1=Sisson |first2=Christian K. |last2=Zacher |year=2006 |isbn=0-253-34886-2 |page=1489 |url= https://books.google.com/books?id=n3Xn7jMx1RYC&pg=PA1489 |publisher=Indiana University Press |access-date=2016-06-04 |url-status=live |archive-date=2023-02-02 |archive-url=https://web.archive.org/web/20230202181649/https://books.google.com/books?id=n3Xn7jMx1RYC&pg=PA1489}}</ref> The CDC 6600 outperformed its predecessor, the [[IBM 7030 Stretch]], by about a factor of 3. With performance of about 1&nbsp;[[FLOPS|megaFLOPS]], the CDC 6600 was the world's fastest computer from 1964 to 1969, when it relinquished that status to its successor, the [[CDC 7600]].