Editing Analog computer (section)

==Decline==
In the 1950s to 1970s, digital computers based on first vacuum tubes, transistors, integrated circuits and then micro-processors became more economical and precise. This led digital computers to largely replace analog computers. Even so, some research in analog computation is still being done. A few universities still use analog computers to teach [[Control theory|control system theory]]. The American company Comdyna manufactured small analog computers.<ref name="1WCta">{{Cite web |url=http://www.comdyna.com/ |title=Analog Computers |website=Comdyna |access-date=2008-10-06 |archive-url=https://web.archive.org/web/20171201031302/http://www.comdyna.com/ |archive-date=2017-12-01 |url-status=dead}}</ref> At Indiana University Bloomington, Jonathan Mills has developed the Extended Analog Computer based on sampling voltages in a foam sheet.<ref name="iz3LX">{{cite web |url=http://www.cs.indiana.edu/~jwmills/ANALOG.NOTEBOOK/klm/klm.html |title=Kirchhoff-Lukasiewicz Machines}}</ref> At the Harvard Robotics Laboratory,<ref name="vqRs1">{{cite web |url=http://hrl.harvard.edu/ |title=Harvard Robotics Laboratory}}</ref> analog computation is a research topic. Lyric Semiconductor's error correction circuits use analog probabilistic signals. [[Slide rule]]s are still used as [[flight computer]]s in [[flight training]].