<html><head></head><body>That is so cool!!!!<br>
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Working everything under a 64k limit is amazing. <br><br><div class="gmail_quote">On October 28, 2015 8:29:30 PM EDT, Alex Carver <agcarver+ale@acarver.net> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="k9mail">On 2015-10-28 13:42, Jim Kinney wrote:<br /><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;"> On Wed, 2015-10-28 at 14:46 -0400, James Sumners wrote:<br /><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"><br /> I am glad I do not work where you work. Redundancy doesn't imply<br /> corruption mitigation. And refusing to allow such to be implemented<br /> because the tool isn't "old" is asinine.</blockquote><br /> It's not that things are refused because they are new. It's rather they<br /> are refused because they are not yet "well understood" and "mature".<br /> Mil-Spec work is _always_ like that. <br /> Often, there are areas where software is never upgraded or changed<br /> because the systems are never networked. Thus any problem can never be<br /> fixed and the process that machine exists for _MUST_ be up at all<br
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times. So, no "new hotness allowed". Imagine being stuck in a world<br /> where "new" was RHEL 5.<br /></blockquote><br />I'll give a real world example that's happening right now. One of the<br />projects here is Voyager (you know the one with the two probes that<br />exited the solar system and are now in interstellar space). The last of<br />the original project members (the project manager) has announced his<br />retirement at 83 years old.<br /><br />Voyager wasn't expected to be operating past ten years after launch<br />(long enough to reach the primary targets Jupiter and Saturn). It was<br />launched in 1977 but design and construction would have started in the<br />very early 70's (mission concept, design and construction of this class<br />is typically 6-10 years) which means the Voyager documents are now over<br />40 years old. It's also still classified as an active mission because<br />it is still returning science data which means making sure the computer<
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/>and instruments on board stay running. Voyager's code is assembly with<br />64 kilobytes of total operational program storage space on board (data<br />is recorded to an 8-track tape).<br /><br />During the flights of the two Voyagers, many modifications to the code<br />had to be made. This involved, among other things, knowing very<br />specific details about the instruments on board each one which turned<br />out to have very subtle differences. The code has to be rewritten from<br />scratch every time because of the limited space. It gets written on the<br />ground, verified, then uploaded.<br /><br />Unfortunately, the data retention policies at the time were not very<br />stringent. Since the mission was expected to last only about 10 years,<br />many documents were not updated and archived properly. Engineers kept<br />details in their heads because they would likely still be working beyond<br />the end of the mission. As the mission continued past its origina
l<br
/>endpoint, this quickly became a problem when changes needed to be made.<br /> Many of the engineers have died taking secrets about the spacecraft<br />with them. In other cases files have been lost to time because the were<br />written in formats that no one knew how to interpret (work is ongoing to<br />recover much of that data). There's even a working replica of the<br />computer in the mission office today where code is tested before upload.<br /> It has been running since 1979 and still needs to be maintained.<br /><br />It was because of this and other early projects (Explorer, Mariner,<br />etc.) that the data usage, retention and archive policy was tightened.<br />That included what software could be used and how generated data could<br />be stored. The entire intent is to maintain an accessible, functional<br />history for scientists and engineers in the event we need to go back to<br />old data for anything. That happens very often.<br /><hr /><br />Ale mailin
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list<br />Ale@ale.org<br /><a href="http://mail.ale.org/mailman/listinfo/ale">http://mail.ale.org/mailman/listinfo/ale</a><br />See JOBS, ANNOUNCE and SCHOOLS lists at<br /><a href="http://mail.ale.org/mailman/listinfo">http://mail.ale.org/mailman/listinfo</a><br /><br /></pre></blockquote></div><br>
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