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{{Infobox computing device
| name = Mitra 15
| image = Mitra-15-ACONIT.jpg
| caption = Front panel of a Mitra 15, from the collection of ACONIT Museum, Grenoble
| developer = Compagnie Internationale d'Informatique (CII)
| family = Minicomputer
| generation = 3rd
| release date = 1971
| discontinued = 1985
| units sold = About 8000 (7929)
| cpu = 16 bits, real-time (32 interruptions level), upgradeable microcode, made of TTL cards plugged onto a backplane
| RAMtype = Core memory, 32 kilowords of 16 bits words (64 KB)
| storage = DRI hard drive (5 MB fixed, 5 MB removable)
Later, 50 MB hard drive
| CPUspeed = 800ns memory cycle (1.25 MHz)
| input = Teletype, Ethernet, Minitel
| successor = Mitra 125, Mitra 225
| logo = Logo-CII-Compagnie-Internationale-Informatique.png
| logo_size = 125px
| predecessor = CII 10010, CII 10020
| os = [[Siris 8]]
}}
The '''Mitra 15''' is a [[minicomputer]] made by the French company [[Compagnie internationale pour l'informatique|CII]] under [[Plan Calcul]], along with the [[CII Iris 50|Iris 50]] and [[CII Iris 80|Iris 80]] mainframe computers. It was marketed from 1971 to 1985 and could function in conjunction with large systems. CII manufactured a thousand Mitra 15 machines until 1975 in its [[Toulouse]] factory, then in Crolles in the suburbs of [[Grenoble]]. A total of 7,929 units were built, most of them for the French market, with a small number sold in Australia, Indonesia, and in other European countries.<ref name=":0">{{Cite web |title=CII 10010 |url=http://www.feb-patrimoine.com/projet/10010/cii_10010.htm |access-date=2023-08-03 |website=www.feb-patrimoine.com}}</ref>
==History==
The Mitra 15 is the successor to the CII 10010,<ref name=":0" /> also called Iris 10, a 16-bit minicomputer released in July 1967.<ref>{{Cite web |title=CII History |url=http://www.feb-patrimoine.com/projet/histoire_informatique/cii_history.htm |access-date=2023-09-01 |website=www.feb-patrimoine.com}}</ref> At the time, CII also produced another 16-bit minicomputer, the CII 10020 (actually a licensed Sigma 3 from SDS) and wanted to replace them both with a new, more powerful design compatible with the latest offering of the company. The Mitra 15 was designed from the outset to complement and network with the most powerful French computer of the time, the CII Iris 80,<ref name=MVI>[http://aconit.inria.fr/omeka/items/show/57 Musée virtuel de l'informatique]</ref> with which it was compatible. Its name is an acronym of {{lang|fr|Mini-machine pour l'Informatique Temps Réel et Automatique}}, meaning “Mini-machine for Real-Time and Automatic Computing”. The first versions featured a [[main memory]] of lithium ferrite cores organized in 16-bit words.<ref name=MVI/> It was designed and developed by a team led by [[Alice Recoque]].<ref>{{cite web |language=fr |author=Alice Recoque |title=Quelques détails sur Alice Recoque, Congrès de la S.I.F., janvier 1976 |url=https://www.societe-informatique-de-france.fr/wp-content/uploads/2016/02/teste-SIF-envoy%C3%A9-par-Alice-Recoque.pdf |website=societe-informatique-de-france.fr |date=January 2016 |access-date=28 January 2021}}</ref><ref>{{cite web |language=fr |author= |title=Portrait de 85 femmes inspirantes du monde des nouvelles technologies |url=https://blog.50a.fr/digital/portrait-de-5-femmes-inspirantes-8-mars |website=50a.fr |date=March 2019 |access-date=28 January 2021}}</ref><ref name="LeF">
{{cite web
|language=fr
|author=Elisa Braun
|title=Elles ont marqué l'histoire de la technologie : Alice Recoque, le génie informatique à la française
|website= Le Figaro
|date=25 July 2018
|url=http://www.lefigaro.fr/secteur/high-tech/2018/07/25/32001-20180725ARTFIG00233-elles-ont-marque-l-histoire-de-la-technologie-alice-recoque-le-genie-informatique-a-la-francaise.php
|access-date=27 July 2018
}}</ref>
The first Mitra 15 was delivered on May 10, 1971, and produced in Crolles then Échirolles.<ref name="bullbou">" Mémoires et archives d'Henri Boucher, Ingénieur Général de l'Armement |[http://www.aconit.org/histoire/iga_boucher/pdf/Vol_E_700-745.pdf]</ref>
[[File:Mitra 15 board.jpg|thumb|Close up on one of the processor board of the Mitra 15 minicomputer]]
Intended for [[command and control]] of industrial processes such as scientific computing, the Mitra 15 was designed to be adaptable to very diverse fields of application, thanks to an innovative microprogramming system and a good price/performance ratio.<ref name ="bullbou"/> Variants of this computer have also been produced according to the needs of CII's customers. The Mitra 15 was also developed into a militarized version, the Mitra 15M.<ref name ="bullbou"/> [[Microprogram]]s use [[firmware]] stored in a ROM, the execution of which causes a simple computer (the micromachine) to always execute the same algorithm, for the instructions of another computer: the macromachine, or simply the machine, which is what is visible to the programmer.
[[File:Mitra 15 rear view.jpg|thumb|Back view of the Mitra 15 minicomputer]]
Only the first version is incompatible with the CII Iris computers of the time, the Iris 50.<ref name ="bullbou"/> The Mitra 15 was widely used as the [[Front-end (computing)|front-end]] for the CII Iris 80 (MCR-2) computer. Initially, it was produced as a simple stand-alone module with external cabinetry. It was succeeded by the Mitra 15–20, Mitra 15–30, and Mitra 15–35, produced from 1972. The Mitra 15-30 and Mitra 15-35 which have an external chassis cabinet with extended configuration and modular drawers<ref name ="bullbou"/> are intended in particular for customers in the telecommunications industry; they were priced from the {{inflation|US|13,000|1972|fmt=eq}} dollars. Later, the low-end Mitra 15M/05 was produced in 1975.
==Competition and innovation==
The first commercially-successful minicomputer, the 12-bit [[Digital Equipment Corporation|DEC]] [[PDP-8]] was introduced in 1965, and sold for {{US$|16,000|1965|round=0}}. In 1969, [[Data General]], founded by ex-DEC engineers introduced the 16-bit [[Data General Nova|Nova]], which sold for {{US$|3995|1969|round=0}}. The [[Hewlett-Packard]] [[HP_2100#2100|HP2000 series]] appeared in the late 1960s and early 1970s.
The main French competitor to the Mitra 15 were the Télémécanique [[:fr:T1600|T1600 [fr]]], introduced in 1971, and its successor, the [[:fr:Solar_(ordinateur)|Solar 16 [fr]]] in 1975, which sold in about 16 000 units.
According to ''Le Monde'', by 1974 the Mitra 15 had achieved revenue of 150 million francs; one eighth of the total sales of the CII, of which "30% was for remote processing" and "around 20%" for export.<ref>« La Compagnie internationale pour l'informatique vient de livrer son millième ordinateur », ''Le Monde'', 9 décembre 1974 [https://www.lemonde.fr/archives/article/1974/12/09/la-compagnie-internationale-pour-l-informatique-livre-son-millieme-ordinateur-mitra-15_2537689_1819218.html]</ref>{{citation-needed|date=May 2023}}
==Users==
===Cyclades packet-switching network===
[[CYCLADES|Cyclades]] was an early packet-switching network developed by [[Louis Pouzin]] in the early 1970s, which played a significant role in the development of the Internet. It used a decentralized approach where Mitra 15 minicomputers acted as routers<ref>{{Cite book |last=Grange |first=Jean-Louis |title=Interlinking of Computer Networks |chapter=Operation of the Cyclades Network |date=1979 |editor-last=Beauchamp |editor-first=Kenneth G. |chapter-url=https://link.springer.com/chapter/10.1007/978-94-009-9431-7_26 |series=NATO Advanced Study Institutes Series |language=en |location=Dordrecht |publisher=Springer Netherlands |pages=411–419 |doi=10.1007/978-94-009-9431-7_26 |isbn=978-94-009-9431-7}}</ref> and allowed for the transmission of data in small packets. Cyclades was a forerunner of the [[Transmission Control Protocol]] (TCP).
===French nuclear program===
The Mitra 15 was used to monitor the deployment of the use of the new generation of electric generators from {{lang|fr|Électricité de France}}, during the French nuclear program. In particular, it was used as part of the transmission network automation master plan, launched in 1973.
The Mitra 15 gradually equipped all of the network's control sites – about a hundred in France – to ensure and manage data exchanges between the remote control equipment of the sites ordered and the regional nodes which control the control of the electricity network. In 1975, EDF 's Mitra 15s were systematically fitted with monitors and printers.<ref>Histoire des premiers EDT, sur le Conservatoire des Télécommunications du Réseau électrique français  [http://www.telecom-reseau-electrique.com/?p=1745]</ref>
===PTT telecom network===
Within the French PTT telecom network, the Mitra 15 was used with CII Iris 80s, due to its ability to handle a large number of interrupts.
===Telecom switches===
The Mitra 15 equipped the telephone switches of the E10N4 between 1972 and 1976, sold by CIT-Alcatel to the PTT.<ref name="bullbou" /> After 1976, because of the lowering of component prices, a fully electronic 2nd generation global telephone switch system, based on new integrated circuits, became affordable.<ref name="ancalc">« Historique des types de commutateurs téléphoniques automatiques en France » sur le site des anciens de la CIT-Alcatel [http://telecommunications.monsite-orange.fr/page-55993eb375ec0.html]</ref>
===Experimental computer science in secondary education===
As part of Plan Calcul, tt was then decided to install computers, on an experimental basis, in 58 high schools. Two minicomputers were selected for the pilot: The Télémécanique T1600 and the Mitra 15.<ref name=":1" />Although the performance of the Mitra was three or four times better than the T1600, the delivery of the Mitra lagged by two months, so it was decided to install more T1600s than Mitras.<ref name="Noyelle">«La Saga du LSE et de sa famille (LSD / LSG / LST)», by Yves Noyelle, du Service Informatique de Supélec, dans la Revue de l'association Enseignement public et informatique (EPI), en 1988 |url=https://www.epi.asso.fr/revue/54/b54p216.htm</ref><ref name=":1">{{cite web |language=fr |author=Association pour un conservatoire de l'informatique et de la télématique |title=Collection ACONIT, les mini-ordinateurs français |url=https://db.aconit.org/dbaconit/consulter.php?db=0&idcollection=71 |website=db.aconit.org |date= |access-date=19 March 2023}}</ref>
===The Ariane rocket===
In [[Kourou]], at the Guiana Space Center, the [[Ariane 1]] control console was built around two Mitra 15s: one for managing electrical systems, the other for fluid systems. The [[Ariane 4]] consoles also used two Mitra 15-30 computers and peripherals for command controls. One in the preparation area (CCD) Dock Command Control, the other in the launch area (CCE) Electrical Command Control. The peripherals have evolved during the launch campaigns and in particular the DRI magnetic head disks which have been replaced by RAM memory disks whose speed of access times has required software reorganizations.
On the launch pad, the Mitra 15, associated with an Intel ''Frontal Table Image'' (FTI),{{what|date=May 2023}} controlled, among other functions, the ignition sequence. A sustainability study of these computers and all the control consoles enabled them to be used until 2003, the date of the last Ariane 4 V159 flight.
==Political decisions in 1976==
CII was handicapped by its 1974-1976 merger with [[Honeywell-Bull]], who were more centered on traditional business computing, and by the abandonment of Unidata, which caused the termination of orders from [[Siemens]].<ref name="mesmin">{{cite news |language= fr|author1= |title=Tribune de Georges Mesmin, député réformateur de Paris, rapporteur du budget de la recherche scientifique  |agency=Le Monde |date=8 May 1976 |url= https://www.lemonde.fr/archives/article/1976/05/08/l-informatique-un-nouveau-pari_2944113_1819218.html}}</ref> Sales of the Mitra 15 were tied by CII with that of the big computer, the Iris 80, to the point that Le Monde asked if CII would not be forced to launch into this market and manufacture its own equipment.<ref name="unan">{{cite news |language= fr|author1=Jean-Michel Quatrepoint |title= C.I.I.-H.-B., un an après|agency=Le Monde  |date=18 September 1976 | url=https://www.lemonde.fr/archives/article/1976/09/18/c-i-i-h-b-un-an-apres_2965930_1819218.html}}</ref> The Mitra 15 mini-computer, a mainstay since 1971 of its distributed computing strategy, was then sold to its shareholder Thomson, who had been opposed for more than a year to the merger of CII with Honeywell-Bull, despite a special mediation mission.<ref name="reconversion">{{cite news|title=L'État versera 200 millions de francs pour aider à la reconversion de l'usine de Toulouse| agency=Le Monde|date=7 April 1976| url=https://www.lemonde.fr/archives/article/1976/04/07/l-etat-versera-200-millions-de-francs-pour-aider-a-la-reconversion-de-l-usine-de-toulouse-de-la-c-i-i_2969433_1819218.html}}</ref>
==Mitra 15 successors==
[[File:Mitra 125 front panel.jpg|thumb|Front panel of a Mitra 125, first successor to the Mitra 15.]]
The Mitra 125, sometimes called "Mitra 15M/125" succeeded the Mitra 15 in 1975. It introduced a [[memory management unit]], with extended addressing capabilities, protected memory and paging support, allowing it to address up to 32 pages of 64 kB for a total of 512 kB. It also added three I/O microcoded processors, and up to sixteen units could be interconnected for distributed  computing.<ref>{{Cite web |title=Mitra |url=http://www.feb-patrimoine.com/english/mitra.htm |access-date=2023-09-04 |website=www.feb-patrimoine.com}}</ref> A version specially designed for the [[Spacelab]],<ref name="bullbou" /> a modular space laboratory used during some of the missions of the American [[Space Shuttle]], was also developed: the Mitra 125 MS.
Its immediate successor, the Mitra 225 was a powerful version<ref>{{cite web|title=Ligne Mitra | url=http://www.feb-patrimoine.com/projet/mitra/mitra.htm}}</ref> built from 1975 around the [[AMD Am2900|AMD 2901]] [[bit-slice]] microprocessors and MOS memory.<ref name="hispr">«Histoire de la microprogrammation», par Alain Guyot, [https://www.electronique-mixte.fr/wp-content/uploads/2018/08/Cours-Microcontr%C3%B4leur-microprocesseur-28.pdf]</ref> This family of processors, easier to program than those of [[Intel]], was also introduced in 1975 by [[Advanced Micro Devices]].
From 1976, Mitra minicomputers were grouped, together in the European Society for Minicomputing and Systems, formed for civilian applications, with the mini-computers T1600 and Solar of Télémécanique (24%) and 9% of IDI.<ref name="bullbou" />
The Mitra 525 ratifies, in a three-bus architecture, the possibilities of extension of the Mitra 225 with which it remains compatible. The 1982 Mitra 625 will only bring detail changes, allowing up to 25% more power.<ref name="bullbou" /> Finally, the 1984 Mitra 725 was produced at a time when SEMS was transferred to Bull, which "didn't deal much with this SEMS, having to deal with Honeywell's [[Honeywell Level 6|Level 6]] as well as the heavy financial losses of the period, 1982-1984.<ref name="bullbou" />
The Mitra 525, 625, and 725 used the [[Emitter-coupled logic|ECL]] MC10800 and MC10802 circuits,<ref name="bullbou" /> introduced by [[Motorola]] in 1975, while Intel's 3002 lost its advantage over competitors.<ref> Encyclopedia of Microcomputers: Volume 4, by Allen Kent, James G. Williams, page 166</ref>
== References ==
{{Reflist}}
==External links==
* [https://bitsavers.org/pdf/cii_honeywell_bull/mitra_15/4057_U_EN_Mitra_15_Reference_manual.pdf Mitra 15 Reference Manual]
* [http://www.feb-patrimoine.com/english/mitra.htm Technical summary at the Fédération des Equipes Bull]
[[Category:Minicomputers]]
[[Category:History of computing in France]]
[[Category:Computers designed in France]]
[[Category:16-bit computers]]