Is the 80286 still in production? Or is it old stock on a shelf somewhere that is used?
Boeing's software fix for the 737 Max overwhelms the plane's computer
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Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#12Does this mean that one of the reasons MCAS relied on a single sensor could be the already saturated CPU? Mindblowing.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#13Is the 80286 still in production? Or is it old stock on a shelf somewhere that is used?
AFAIK, Airbus has stockpiled huge amounts of legacy CPUs in climate controlled conditions. Boeing must have done the same
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#14Simple question: Why doesn't Boeing upgrade to i386 for their new planes? I heard it's available for aerospace applications.
Simple speculation: The software makes heavy use of 80286 protected mode and its quirks, which in an embedded hi-rel environment is fine. An areospace 80386 doesn't necessarily have higher throughput (remember, these are in-order-execution architectures), if run at the same clockrate. And you probably can't simply increase the clockrate, since some timing may depend on the CPU clock, due to busy-loop waiting, or some sensor readout/communication using the CPU clock for protocol timing.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#15Could this be considered unacknowledged technical debt?
Maybe we're just ignorant of the available chips for this use case. Otherwise just reads like they've been kicking the can of system redesign/refactoring down the road for decades. It appears that short term thinking abounds in every industry.
Something like that, thinking about it as a kind of senescence, arriving at a point where they realize that the system is depleted. It needs to be planned for.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#16From the article ----------- Boeing says that it can again fix the software to avoid the problem the FAA just found. It is doubtful that this will be possible. The software load is already right at the border, if not above the physical capabilities of the current flight control computers. The optimization potential of the software is likely minimal. MCAS was a band aid. Due to the new engine position the 737 MAX vers…
Damn, I hope those senior engineers charge Boeing an arm and a leg when they are asked to come back.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#17As has been discussed on HN, this whole 737 MAX flaw is not a software problem. Boeing wants you to believe it is. The flaw is actually a physical design problem of the aircraft. Even if the software were to work perfectly, the plane is still flawed. The only real fix is not to fly the 737 MAX.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#18Simple question: Why doesn't Boeing upgrade to i386 for their new planes? I heard it's available for aerospace applications.
Simple speculation: The software makes heavy use of 80286 protected mode and its quirks, which in an embedded hi-rel environment is fine. An areospace 80386 doesn't necessarily have higher throughput (remember, these are in-order-execution architectures), if run at the same clockrate. And you probably can't simply increase the clockrate, since some timing may depend on the CPU clock, due to busy-loop waiting, or some…
IIRC there were huge swathes of 'gotchas' with running 286 pmode code in 386 pmode, to the point where lots of code simply wouldn't work at all.
(One thing that springs to mind was that the way addresses running past the end of a segment worked was different)
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#19As has been discussed on HN, this whole 737 MAX flaw is not a software problem. Boeing wants you to believe it is. The flaw is actually a physical design problem of the aircraft. Even if the software were to work perfectly, the plane is still flawed. The only real fix is not to fly the 737 MAX.
Or admit it's a hardware and aircraft design problem and go through the exponentially more expensive process of fixing it.
Re: Boeing's software fix for the 737 Max overwhelms the plane's computer
#20Simple question: Why doesn't Boeing upgrade to i386 for their new planes? I heard it's available for aerospace applications.
Forget about upgrading - they could just press the Turbo button on that 286. That's what it's there for!