I remember some of the history of IBM's smallest program: http://en.m.wikipedia.org/wiki/IEFBR14
In addition to the changes my friend John Pershing mentions, I recall bug reports due to inadequate comments, and because the number of changes per line of code was high, IEFBR14 was high on a list of modules that needed a rewrite... Software work helps one with humility... 73 de Dick, K6KR > On Jan 17, 2015, at 14:30, KENT TRIMBLE <[email protected]> wrote: > > Facts can also be factual. > > Kent K9ZTV > > > /On November 10, 1999, the Mars Climate Orbiter Mishap Investigation Board > released a Phase I report, detailing the suspected issues encountered with > the loss of the spacecraft. Previously, on September 8, 1999, Trajectory > Correction Maneuver-4 was computed and then executed on September 15, 1999. > It was intended to place the spacecraft at an optimal position for an orbital > insertion maneuver that would bring the spacecraft around Mars at an altitude > of 226 kilometers on September 23, 1999. However, during the week between > TCM-4 and the orbital insertion maneuver, the navigation team indicated the > altitude may be much lower than intended at 150 to 170 kilometers. > Twenty-four hours prior to orbital insertion, calculations placed the orbiter > at an altitude of 110 kilometers; 80 kilometers is the minimum altitude that > Mars Climate Orbiter was thought to be capable of surviving during this > maneuver. Post-failure calculations showed that the spacecraft was on a > trajectory that w ould have taken the orbiter within 57 kilometers of the surface, where the spacecraft likely disintegrated because of atmospheric stresses. / > > /_The primary cause of this discrepancy was that one piece of ground software > supplied by _Lockheed Martin > <http://en.wikipedia.org/wiki/Lockheed_Martin>_produced results in a _United > States customary unit > <http://en.wikipedia.org/wiki/United_States_customary_units>_("American"), > contrary to its Software Interface Specification (SIS), while a second > system, supplied by _NASA <http://en.wikipedia.org/wiki/NASA>_, that used > those results expected them to be in metric units, in accord with the SIS. > _Software that calculated the total impulse produced by thruster firings > calculated results in pound-seconds. The trajectory calculation used these > results to correct the predicted position of the spacecraft for the effects > of thruster firings. This software expected its inputs to be in > newton-seconds.^[16] > <http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#cite_note-Mishap-17> / > > // > > /The discrepancy between calculated and measured position, resulting in the > discrepancy between desired and actual orbit insertion altitude, had been > noticed earlier by at least two navigators, whose concerns were dismissed. A > meeting of trajectory software engineers, trajectory software operators > (navigators), propulsion engineers, and managers, was convened to consider > the possibility of executing Trajectory Correction Maneuver-5, which was in > the schedule. Attendees of the meeting recall an agreement to conduct TCM-5, > but it was ultimately not done./ > > > >> On 1/17/2015 1:41 PM, Lynn W. Taylor, WB6UUT wrote: >> Good quip, but it doesn't agree with the findings of the Mars Climate >> Orbiter Mishap Investigation Board. >> >> Facts can be so inconvenient. >> >>> On 1/17/2015 11:15 AM, KENT TRIMBLE wrote: >>> Good quips always sail over at least one person's head. >>> >>> K9ZTV >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] >> >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2015.0.5645 / Virus Database: 4260/8946 - Release Date: 01/17/15 >> >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
