SpaceX News

[303]

well, when i did computer science degree , i was taught that no industrial system with safety-critical tasks would ever use c++ because it simply wasnt built to handle parallelisation like ada was, and didnt have safety-critical features built in

from wikipedia :

Because of Ada's safety-critical support features, it is now used not only for military applications, but also in commercial projects where a software bug can have severe consequences, e.g. aviation and air traffic control, commercial rockets (e.g. Ariane 4 and 5), satellites and other space systems, railway transport and banking.[6] For example, the fly-by-wire system software in the Boeing 777 was written in Ada. The Canadian Automated Air Traffic System was written in 1 million lines of Ada (SLOC count). It featured advanced distributed processing, a distributed Ada database, and object-oriented design. Ada is also used in other air traffic systems, e.g. the UK’s next-generation Interim Future Area Control Tools Support (iFACTS) air traffic control system is designed and implemented using SPARK Ada [12] It is also used in the French TVM in-cab signalling system on the TGV high speed rail system, and the metro suburban trains in Paris, London, Hong Kong and New York City.[6][13]

In other words, when you need that valve shut down on the reactor, you need it shut down immediately, rather than wait 300 ms for some library routine to return true or false, or some error to cause your main routine to be wasting time in some error handling routine == 3 mile island

I'm amazed that c++ would be considered for use anywhere near the latest and greatest fighter plane.

[KitemanSA]

Maybe it's the COTS kick rearing its ugly head again.

[paperburn1]

Maybe it's the COTS kick rearing its ugly head again.

That I can beleive

[happyjack27]

Linux is written in C.

[hanelyp]

Linux is written in C.

The standard configuration linux kernel isn't well suited to real time control applications, or at least wasn't last I looked. That kind of support is wasted on a typical PC. But a scheduler designed for real time support is available. Part of the design separates tasks needing hard real time support from normal tasks that can afford some delay.

[paperburn1]

And is self terminating, remember the Y2K problem. Unix has that as well in the 32 bit system. On 19 January 2038 on 32 bit Unix systems, the current time will roll over from a zero followed by 31 ones (0x7FFFFFFF) to a one followed by 31 zeros (0x80000000), which will reset time to the year 1901 or 1970, depending on implementation But hopefully we will all be 64 bit systems by then and we will have 300 billion years to correct that clock problem

[GIThruster]

Thunderbirds are GO for launch!

http://www.facebook.com/SpaceX

Watch on Friday!

[DeltaV]

http://www.aviationweek.com/Article.asp ... 83.xml&p=1

[Skipjack]

Was a beautiful launch. Finally a day launch with the Dragon. Some minor problems with a stuck He - oxygen tank pressurization valve (frozen shut?) on the dragon pods. Was a small scare there, but the SpaceX crew solved it quickly. Everything back on track now

[Skipjack]

http://www.youtube.com/watch?feature=pl ... Ivr6JF1K-8
There was a new Grasshopper- hopp on Thursday. Twice as high as last time. There is a rumor that they will try a mid flight engine reignition next time.

[paperburn1]

http://www.youtube.com/watch?feature=pl ... Ivr6JF1K-8
There was a new Grasshopper- hopp on Thursday. Twice as high as last time. There is a rumor that they will try a mid flight engine reignition next time.

Did anybody else notice the man in black standing on the platform

[mvanwink5]

Johnny Cash dressed in black leather?

[Skipjack]

Johnny Cash dressed in black leather?

Yeah, its a manequin that they dressed up as a cowboy. He was already there during the last flight as well.

[DeltaV]

More info.
http://www.aviationweek.com/Article.asp ... 557797.xml

[JoeP]

well, when i did computer science degree , i was taught that no industrial system with safety-critical tasks would ever use c++ because it simply wasnt built to handle parallelisation like ada was, and didnt have safety-critical features built in

from wikipedia :

Because of Ada's safety-critical support features, it is now used not only for military applications, but also in commercial projects where a software bug can have severe consequences, e.g. aviation and air traffic control, commercial rockets (e.g. Ariane 4 and 5), satellites and other space systems, railway transport and banking.[6] For example, the fly-by-wire system software in the Boeing 777 was written in Ada. The Canadian Automated Air Traffic System was written in 1 million lines of Ada (SLOC count). It featured advanced distributed processing, a distributed Ada database, and object-oriented design. Ada is also used in other air traffic systems, e.g. the UK’s next-generation Interim Future Area Control Tools Support (iFACTS) air traffic control system is designed and implemented using SPARK Ada [12] It is also used in the French TVM in-cab signalling system on the TGV high speed rail system, and the metro suburban trains in Paris, London, Hong Kong and New York City.[6][13]

In other words, when you need that valve shut down on the reactor, you need it shut down immediately, rather than wait 300 ms for some library routine to return true or false, or some error to cause your main routine to be wasting time in some error handling routine == 3 mile island

I'm amazed that c++ would be considered for use anywhere near the latest and greatest fighter plane.

FWIW, I think there are C/C++ compilers available that are specifically for real time systems and applications.

(OT: You reminded me of a particular class I had. When I was an undergrad back in the 90s, there was a very good professor that was a huge fan of Ada for all of these reasons you quoted and stated. To him, this was the next big language... Yet the language that ruled the day was C/C++ which we knew as well as several asm languages. Since this Ada-fan professor could not get Ada into the curriculum to be taught directly, he had us implement an Ada compiler in C w/Lexx/Yacc in Unix. Pretty good solution and quite fun. One young lady in the class did pursue an Ada career -- the last I heard recently she was still making a good living writing code for military.)