Editing Computer mouse (section)

=== First rolling-ball mouse ===
{{anchor|Rollkugel}}[[File:Telefunken Rollkugel RKS 100-86.jpg|thumb|left|The ball-based [[Telefunken]] {{lang|de|Rollkugelsteuerung}} ''RKS&nbsp;100-86'' from 1968]]

On 2 October 1968, three years after Engelbart's prototype but more than two months before his public [[The Mother of All Demos|demo]], a mouse device named ''{{lang|de|Rollkugelsteuerung}}'' (German for "Trackball control") was shown in a sales brochure by the German company [[AEG (German company)|AEG]]-[[Telefunken]] as an optional input device for the SIG&nbsp;100 vector graphics terminal, part of the system around their process computer [[Telefunken TR 86|TR&nbsp;86]] and the {{ill|Telefunken TR 440{{!}}TR 440|de|TR&nbsp;440}} main frame.<ref name="Neubauer_1968" /><ref name="CHM_SIG-100" /><ref name="Telefunken_1971" /><ref name="Bülow_2009_Rollkugel" /> Based on an even earlier<!-- somewhen between 1963 and 1965 --> trackball device, the mouse device had been developed by the company in 1966 in what had been a parallel and [[independent discovery]].<ref name="Bülow_2009_Rollkugel" /><ref name="HNF_2016_Blog" /> As the name suggests and unlike Engelbart's mouse, the Telefunken model already had a ball (diameter 40&nbsp;mm, weight 40&nbsp;g<ref name="Yacoub-Turfa-Maurer_2016" />) and two mechanical 4-bit<ref name="Yacoub-Turfa-Maurer_2016" /><ref name="Mueller_2018" /> rotational [[position transducer]]s<ref name="Yacoub-Turfa-Maurer_2016" /><ref name="Steinbach_2018" /><ref name="Mueller_2018" /> with [[Gray code]]-like<ref name="Yacoub-Turfa-Maurer_2016" /><ref name="Mueller_2018" /><ref group="nb" name="NB_Rollkugel_Encoder" /> states, allowing easy movement in any direction.<ref name="Ebner_2018" /> The bits remained stable for at least two successive states to relax [[debouncing]] requirements.<ref name="Yacoub-Turfa-Maurer_2016" /><ref name="Mueller_2018" /> This arrangement was chosen so that the data could also be transmitted to the TR&nbsp;86 front-end process computer and over longer distance [[telex line]]s with {{circa}}{{sp}}50&nbsp;[[baud]].<ref name="Steinbach_2018" /> Weighing {{convert|465|g}}, the device with a total height of about {{cvt|7|cm}} came in a {{circa}}{{sp}}{{cvt|12|cm}} diameter hemispherical injection-molded thermoplastic casing featuring one central push button.<ref name="Yacoub-Turfa-Maurer_2016" />

[[File:Telefunken Rollkugel RKS 100-86 (bottom).jpg|thumb|right|The bottom side of the Telefunken {{lang|de|Rollkugel}} ''RKS&nbsp;100-86'' shows the ball]]

As noted above, the device was based on an earlier trackball-like device (also named ''{{lang|de|[[Rollkugel (trackball device)|Rollkugel]]}}'') that was embedded into radar flight control desks.<ref name="HNF_2016_Blog" /> This trackball had been originally developed by a team led by {{ill|Rainer Mallebrein|de}} at Telefunken {{lang|de|Konstanz}} for the German ''{{lang|de|{{ill|Bundesanstalt für Flugsicherung|de}}}}'' (Federal Air Traffic Control). It was part of the corresponding workstation system SAP&nbsp;300 and the terminal SIG&nbsp;3001, which had been designed and developed since 1963.<ref name="Steinbach_2018" /> Development for the TR&nbsp;440 main frame began in 1965.<ref name="Telefunken_1966" /><ref name="Steinbach_2018" /> This led to the development of the TR&nbsp;86 process computer system with its SIG&nbsp;100-86<ref name="Bülow_2009_Rollkugel" /><ref name="CHM_SIG-100" /> terminal. Inspired by a discussion with a university customer, Mallebrein came up with the idea of "reversing" the existing {{lang|de|Rollkugel}} trackball into a moveable mouse-like device in 1966,<ref name="Steinbach_2018" /> so that customers did not have to be bothered with mounting holes for the earlier trackball device. The device was finished in early 1968<!-- Steinbach has an obvious typo: 1966/1968 -->,<ref name="Steinbach_2018" /> and together with [[light pen]]s and [[trackball]]s, it was commercially offered as an optional input device for their system starting later that year.<ref name="Neubauer_1968" /><ref name="CHM_SIG-100" /><ref name="Telefunken_1971" /><ref name="Telefunken_1972" /> Not all customers opted to buy the device, which added costs of {{currency|1500|DM}} per piece to the already up to 20-million DM deal for the main frame, of which only a total of 46 systems were sold or leased.<ref name="Bülow_2009_Rollkugel" /><ref name="Holland_2019" /> They were installed at more than 20 German universities including [[RWTH Aachen]], [[Technische Universität Berlin]], [[University of Stuttgart]]<ref name="Vaihingen_2016" /><ref name="Borchers_2016" /> and [[University of Konstanz|Konstanz]].<ref name="Ebner_2018" /> Several {{lang|de|Rollkugel}} mice installed at the [[Leibniz Supercomputing Centre]] in Munich in 1972 are well preserved in a museum<!-- another sources states that Garching/Munich has 4 Rollkugeln -->,<ref name="Bülow_2009_Rollkugel" /><ref name="OldMouse_Telefunken" /><ref name="HNF_2016_Blog" /> two others survived in a museum at Stuttgart University,<ref name="Vaihingen_2016" /><ref name="Yacoub-Turfa-Maurer_2016" /><ref name="HNF_2016_Blog" /> two in Hamburg<!-- one at the university, the other at Jürgen Müller -->, the one from Aachen at the [[Computer History Museum]] in the US,<ref name="CHM_RKS-100" /><ref name="HNF_2016_Blog" /> and yet another sample was recently donated to the [[Heinz Nixdorf MuseumsForum]] (HNF) in Paderborn.<ref name="HNF_2019_Presentation" /><ref name="Holland_2019" /> Anecdotal reports claim that Telefunken's attempt to patent the device was rejected by the German Patent Office due to lack of inventiveness.<ref name="HNF_2016_Blog" /><ref name="Ebner_2018" /><ref name="Holland_2019" /><ref name="Steinbach_2018" /> For the air traffic control system, the Mallebrein team had already developed a precursor to [[touch screen]]s in form of an ultrasonic-curtain-based pointing device in front of the display.<ref name="Steinbach_2018" /> In 1970, they developed a device named "[[Touchinput]]-{{lang|de|Einrichtung}}" ("touch input device") based on a conductively coated glass screen.<ref name="Ebner_2018" /><ref name="Steinbach_2018" />