Editing Mars Pathfinder (section)

===On-board computer===
{{See also|Comparison of embedded computer systems on board the Mars rovers}}

The [[embedded system|embedded]] computer on board the ''Sojourner'' rover was based around the 2&nbsp;MHz<ref>{{cite web |url=http://mars.jpl.nasa.gov/MPF/rover/faqs_sojourner.html#cpu |title=Mars Pathfinder FAQs - Sojourner CPU |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20141229132636/http://mars.jpl.nasa.gov/MPF/rover/faqs_sojourner.html#cpu |archive-date=December 29, 2014 |url-status=live }}</ref> [[Intel 80C85]] [[Central processing unit|CPU]] with 512&nbsp;[[Kilobyte|KB]] of [[Random access memory|RAM]] and 176&nbsp;KB of [[flash memory]] [[solid state disk|solid-state]] [[Data storage device|storage]], running a [[cyclic executive]].<ref name="ieeecomputer">{{cite journal |first1=Max |last1=Bajracharya |first2=Mark W. |last2=Maimone |first3=Daniel |last3=Helmick |title=Autonomy for Mars rovers: past, present, and future |journal=[[Computer (journal)|Computer]] |publisher=[[IEEE Computer Society]] |date=December 2008 |volume=41 |number=12 |pages=44–50 |doi=10.1109/MC.2008.479 |s2cid=9666797 |issn=0018-9162 |url=http://users.etown.edu/w/wunderjt/ITALY_2009/PUBLICATION_MARS_SPIRIT_ALL_PATH_PLANNING_JPL.pdf |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20160304095252/http://users.etown.edu/w/wunderjt/ITALY_2009/PUBLICATION_MARS_SPIRIT_ALL_PATH_PLANNING_JPL.pdf |archive-date=March 4, 2016 |url-status=live }}</ref>

The computer of the ''Pathfinder'' lander was a [[IBM RAD6000|Radiation Hardened IBM Risc 6000]] Single Chip (Rad6000 SC) [[Central processing unit|CPU]] with 128&nbsp;MB of RAM and 6&nbsp;MB of [[EEPROM]]<ref>{{cite web | url=http://quest.arc.nasa.gov/mars/ask/about-mars-path/pathfinder_computer.txt | title="QUESTION: What type of computer is the Pathfinder utilizing? ..." (NASA Quest Q&A) | date=1997 | access-date=July 21, 2015 | publisher=[[NASA]] | archive-url=https://web.archive.org/web/20160307043527/http://quest.arc.nasa.gov/mars/ask/about-mars-path/pathfinder_computer.txt | archive-date=March 7, 2016 | url-status=dead }}</ref><ref>{{cite web | url=http://quest.arc.nasa.gov/mars/ask/about-rover/Why_to_use_a_80C85_microprocessor_in_Rover_.txt | title="QUESTION: When it was designed, why was only a single 80C85 CPU used? ..." (NASA Quest Q&A) | date=1997 | access-date=July 21, 2015 | publisher=[[NASA]] | archive-url=https://web.archive.org/web/20150723003545/http://quest.arc.nasa.gov/mars/ask/about-rover/Why_to_use_a_80C85_microprocessor_in_Rover_.txt | archive-date=July 23, 2015 | url-status=dead }}</ref> and its [[operating system]] was [[VxWorks]].<ref name=Wind_River>{{cite web | url=http://www.windriver.com/news/press/pr.html?ID=314 | title=Wind River Powers Mars Exploration Rovers—Continues Legacy as Technology Provider for NASA's Space Exploration | date=June 6, 2003 | access-date=August 28, 2009 | publisher=[[Wind River Systems]] | archive-url=https://web.archive.org/web/20100106090354/http://www.windriver.com/news/press/pr.html?ID=314 | archive-date=January 6, 2010 | url-status=live }}</ref>

The mission was jeopardised by a [[Concurrent computing|concurrent]] software bug in the lander,<ref>Parallel sparking: Many chips make light work, Douglas Heaven, ''New Scientist'' magazine, issue 2930, August 19, 2013, p44. [https://www.newscientist.com/article/mg21929301.000-parallel-sparking-many-chips-make-light-work.html?page=2 Online (by subscription)] {{Webarchive|url=https://web.archive.org/web/20141006101728/http://www.newscientist.com/article/mg21929301.000-parallel-sparking-many-chips-make-light-work.html?page=2 |date=October 6, 2014 }}</ref> which had been found in preflight testing but was deemed a glitch and therefore given a low priority as it only occurred in certain unanticipated heavy-load conditions, and the focus was on verifying the entry and landing code. The problem, which was reproduced and corrected from Earth using a laboratory duplicate thanks to the logging and debugging functionality enabled in the flight software, was due to [[Reset (computing)|computer resets]] caused by [[priority inversion]]. No scientific or engineering data was lost after a computer reset, but all the following operations were interrupted until the next day.<ref>{{cite web |url=http://research.microsoft.com/en-us/um/people/mbj/Mars_Pathfinder/Authoritative_Account.html |title=What really happened on Mars? – Authoritative Account |first=Glenn E. |last=Reeves |work=Microsoft.com |date=December 15, 1997 |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20150611035733/http://research.microsoft.com/en-us/um/people/mbj/mars_pathfinder/authoritative_account.html |archive-date=June 11, 2015 |url-status=live }}</ref><ref>{{cite web |url=http://research.microsoft.com/en-us/um/people/mbj/Mars_Pathfinder/ |title=What really happened on Mars? |first=Michael B. |last=Jones |work=Microsoft.com |date=December 16, 1997 |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20150612010836/http://research.microsoft.com/en-us/um/people/mbj/mars_pathfinder/ |archive-date=June 12, 2015 |url-status=live }}</ref> Four resets occurred (on July 5, 10, 11 and 14) during the mission,<ref>{{cite web|url= http://www.oarval.org/missionsr2.htm|title= The Mars Pathfinder Mission Status Reports &mdash; Second Week|publisher= Office of the Flight Operations Manager &ndash; Mars Pathfinder Project|access-date= October 24, 2015|archive-url= https://web.archive.org/web/20160104210211/http://www.oarval.org/missionsr2.htm|archive-date= January 4, 2016|url-status= live}}</ref> before patching the software on July 21 to enable [[priority inheritance]].<ref>{{cite web|url= http://www.oarval.org/missionsr3.htm|title= The Mars Pathfinder Mission Status Reports &mdash; Third Week|publisher= Office of the Flight Operations Manager &ndash; Mars Pathfinder Project|access-date= October 24, 2015|archive-url= https://web.archive.org/web/20160410091935/http://www.oarval.org/missionsr3.htm|archive-date= April 10, 2016|url-status= live}}</ref>