Marcus, > > phil henshaw wrote: > > Are there self-protecting sentinel circuits or routines to > catch them > > in the act and shut them down? > A couple examples come to mind: > > 1) floating point hardware knows when calculations have gone > bad due to > underflow, overflow, divide by zero, etc. The operating > system kernel > can notice these and signal them as exceptions, if the user prefers. > The sanity checks are in hardware as are the task switching / > recovery mechanisms for inspecting them.
Not sure I understand. What's an 'exception'. Is it related to what I was asking about, the chain of conditions getting trapped in increasing complexity, or does it mostly refer to just non-existent address faults and things like that? You say 'sanity checks' are hardware based. Is 'insanity' just anything that doesn't work, or is it more specific in the kinds of things that are the persistent dangers of faulty programming? Do any of the kinds of common exceptions have developmental process curves? You mentioned a "hierarchy of exception types" in your last post. Would that include some that take off right away and some that sputter and then blow up to fry the chip, and things like that? If there are torrents of signals that push the physical limits of the hardware I think they'd have locally unique emergent properties if you looked at them closely with that in mind. > > 2) The memory management unit of computer knows about the > mapping from > physical addresses to virtual ones and knows the difference between > valid and invalid memory addresses. Addresses can be handed out and > reclaimed such that bad addresses due to programming mistakes cause > hardware traps (e.g. the Electric fence malloc library). A > crude form > of this is for Unix users is the segfault or a bus error signals. > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > lectures, archives, unsubscribe, maps at http://www.friam.org > > ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
