From: Jay Blosser <firstname.lastname@example.org> Organization: Lockheed Martin Control Systems Date: 08 Aug 96 12:11:48 References: 1 2 3 4 5
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Karl Swartz wrote: > > --- snip ---- > > For what it's worth, on the 777, Boeing started off with a similar > strategy, but ended up abandoning both hardware and software diver- > sity. Instead of spending several times as much money to support > several development efforts, they spent the money saved on doing more > rigorous review and testing of the software. It remains to be seen > whether the result was better, worse, or just different, but at least > they didn't bet on an illusion of diversity. I may be wrong, but I'm under the impression that the 777 Primary Flight Computers employ three different CPU's per channel (68040, 80486, ???) but all are programmed in the same high-level language (Ada ?). Rumor has it that Boeing backed out of dis-similar software in the PFC when they saw its expense and realized the marginal effectiveness of the generic fault immunity that it provided. Jay Blosser All opinions are my own and are not intended to reflect those of others, including my employer.