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Their task are very specific not really leaving room for flexibility. You can almost compare the importance of these systems working exactly as expected with the physical parts of the shuttle.
Earlier quoted context omitted.
The shuttle uses 4 separate 1.2MHz IBM AP-101 operating in lockstep / redundant systems, with a 5th running an independent system. I assume the fifth is setup in case of software failures. http://en.wikipedia.org/wiki/IBM_AP-101 http://en.wikipedia.org/wiki/Space_Shuttle PS: It's easy to forget just how old and hacked together the Space Shuttle is: Historically, the Shuttle was not launched if its flight would run fr…
That's weird. Why would they even need date logic in the flight software?
I remember my Digital Circuits prof saying the Apollo Flight Computer was constructed out of thousands of NOR-gates. At the time I was struggling to comprehend how to construct a basic circuit, so I was wow'd (and still am). http://en.wikipedia.org/wiki/Apollo_Guidance_Computer
nand is more likely.
Here is an article about developing the 'perfect' software that runs the shuttle: "They Write the Right Stuff" http://www.fastcompany.com/node/28121/print
edit: woah, feature-fail == bug? Why'd it take them until 2007 to not have to reboot whenever they reached a new year? I'd call that a rather significant, costly bug, even if they don't, and it may very well be one of the longest-running in actively-developed software.
I'd like to hear how the code of the new commercial space companies, like SpaceX, compares.
The shuttle software isn't necessarily a good engineering solution.Spending the same time/effort/budget on a more critical part might have saved some of the shuttle failures.
If you think of it in aircraft terms, is it better to spend $ making the avionics software 99.9999% reliable rather than 99.999% or is it better to fit smoke hoods/more exits/better weather radar etc.
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And it's 260 engineers to write 420 KLOC. This is why software is buggy; it's to expensive to make it not buggy.
And it required 380 engineers to build the Burj Dubai. The only difference is for most software projects it is acceptable to have "bugs" as customers will still pay for it, even if it's in a poor state of quality. But "bugs" in a 2,717 ft tower are unacceptable. It comes down to, in general the cost of a bug in most software is relatively low compared to other engineering disciplines. Of course if the software is cri…
The point of engineering is to make a system that is resilient to a certain level of faults. That's why the tower doesn't collapse if there is a 0.1 mm crack in one of the bolts.
Earlier quoted context omitted.
The shuttle uses 4 separate 1.2MHz IBM AP-101 operating in lockstep / redundant systems, with a 5th running an independent system. I assume the fifth is setup in case of software failures. http://en.wikipedia.org/wiki/IBM_AP-101 http://en.wikipedia.org/wiki/Space_Shuttle PS: It's easy to forget just how old and hacked together the Space Shuttle is: Historically, the Shuttle was not launched if its flight would run fr…
That's weird. Why would they even need date logic in the flight software?
A GPS string might erroneously say it's day 367 or be one character too long because it printed 20010 or a telemetry link might ask for 4million readings because it calculated "-1"
Earlier quoted context omitted.
And it's 260 engineers to write 420 KLOC. This is why software is buggy; it's to expensive to make it not buggy.
And it required 380 engineers to build the Burj Dubai. The only difference is for most software projects it is acceptable to have "bugs" as customers will still pay for it, even if it's in a poor state of quality. But "bugs" in a 2,717 ft tower are unacceptable. It comes down to, in general the cost of a bug in most software is relatively low compared to other engineering disciplines. Of course if the software is cri…
People have a tendency to overlook "bugs" in architecture because of the immutability of the medium. But once you start noticing that the HVAC is uneven on your floor, the hot water takes five minutes for ramp up in your office's break room and the conduit runs for networking are bizarre you start to understand that architects and builders run into design and implementation problems as well.
In fact they have their own word for patching. Renovations.
Earlier quoted context omitted.
And it required 380 engineers to build the Burj Dubai. The only difference is for most software projects it is acceptable to have "bugs" as customers will still pay for it, even if it's in a poor state of quality. But "bugs" in a 2,717 ft tower are unacceptable. It comes down to, in general the cost of a bug in most software is relatively low compared to other engineering disciplines. Of course if the software is cri…
The Burj Dubai, like any other structure is full of bugs. The point of engineering is to make a system that is resilient to a certain level of faults. That's why the tower doesn't collapse if there is a 0.1 mm crack in one of the bolts.