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Simple question: Why doesn't Boeing upgrade to i386 for their new planes? I heard it's available for aerospace applications.
by bcaa7f3a8bbc 7y ago
Simple question: Why doesn't Boeing upgrade to i386 for their new planes? I heard it's available for aerospace applications.
- crocal 7y agoI don’t have evidence, but most likely, it is to avoid the related costs and risks of certification of this « new » CPU for its intended usage. Not only the CPU but all the software stack needs to be re-proven safe, including compilers and test tools. Note: this is not necessarily a stupid decision.
- rbanffy 7y agoA simpler solution would be to use the same CPU done with a slightly newer process to allow a higher clock rate. That would ease the recertification process. If you think they are at best 40 MHz 286 parts, the best that was available by then, running software derived from previous releases that ran on slower chips, there is plenty of room for improvement. IIRC, you can get a modern 65816 (the 16-bit descendant of the 6502) in 300+ MHz. And I wouldn't expect it to be on a cutting edge process. That considered, it's entirely possible most of the time is being consumed by reading the sensors. In that case, the sensor communication would need to be upgraded and recertified.
- bcaa7f3a8bbc 7y agoYes, I'm familiar with second-source 6502. Also, I've seen the Rabbit2000 processor, it's basically a Z80 running at 50 MHz. But I wasn't aware that 80286 has any modern second-source clones. Are there?
- rbanffy 7y agoI don't know, but it wouldn't be too hard. Or expensive, in relation to bleeding edge semiconductors. Fun thing: I remember a 40 MHz 286 desktop at one point. Wikipedia tells me they only went to 25 MHz. That's some overclocking... Fun fact #2: with a feature size of 1.5 µm, one could fit an entire 6502 done in 7 nm process on top of a single 80286 transistor.
- dvdbloc 7y agoWith that comes a large amount of verification scope and effort. It is much easier to verify inside and out a small, non complex design running on an incredibly well understood simple platform.
- datenwolf 7y agoSimple 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.
- NikkiA 7y agoIIRC 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)
- rbanffy 7y agoA batch of CPUs of 286 complexity on a more modern process can't be that high compared to the development of a new aircraft (which the MAX kind of is).
- 0815test 7y agoForget about upgrading - they could just press the Turbo button on that 286. That's what it's there for!
- ChuckNorris89 7y agoThanks for making me chuckle early in the morning.
- laythea 7y agoThat's a great comment!
- rbanffy 7y agoOn my boxes, pressing the Turbo button donwclocked them to make Zaxxon playable.