On Sat, 14 Feb 2004 09:27:30 +1300, Steve Wray said: > DRM (Digital Restrictions Management)could,effectively, > make DRM compliant PCs such that there are programs > that they cannot run, hence they would not be Turing complete. Well.. actually you got that backwards. A machine can be Turing complete and still not be able to run every possible program - that was the point of the Turing halting problem (which happens to be the same thing as Godel's Theorem phrased differently). For it to be Turing-*incomplete* there have to be almost no programs that it can run. Basically, if it has enough smarts to run a simulator of a Turing Machine, it's Turing-complete - and all you need for THAT is a decrement instruction, a 'test and skip next if zero' instruction, and a branch instruction. One guy even managed to get rid of conditional branches/skips: http://page.mi.fu-berlin.de/~rojas/misc.ps On the other hand, it's quite possible to end up looking like a WebTV, where there *isn't enough* user-accessible functionality to become Turing-complete, which is (a) what the DRM crew wants and (b) what I think you actually meant to say... :) > I didn't mean that DRM would help in firing sysadmins. It would probably suffice against the average MCSE. ;)
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