On 16 May 2011 20:03, John McKown <joa...@swbell.net> wrote: > Oh, well, personally, I like the ARM architecture. But it is very > fragmented right now. I have an architecture book on ARM v6. And much of > it has the note of "IMPLEMENTATION DEFINED" on things which are not > specifically mandated. I think this is because ARM is used from small > embedded systems to things like smartphone and now iPAD and tablets. > There are also a lot of things are marked UNPREDICTABLE. Who knows what > that will do? Not guaranteed to do anything in particular. Might cause > an exception, or a hardware failure, or ??? . Very weird. Makes the z > architecture look like it was designed by a super-genius. Or somebody > with OCD. <grin>.
A very quick look at the zArch POO finds around 170 occurences of the word "unpredictable". And that is a very good thing; IBM has always been very clear about what unpredictable means, and they don't use the word lightly. Certainly unpredictable does not include "causing hardware failure". Whether other hardware makers use it more casually, I don't know, but I suspect they do. Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
