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???
10/28/09 15:08
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#170134 - Interesting anecdote regarding timers:
Responding to: ???'s previous message
Erik Malund said:
a very good way to get random numbers is to have a timer free running at highest possible speed and reading it when some external event (e.g. keypress, UART char received, ...) happens.


This reminds me of a programming competition that one of the computer magazines I read held last year. The goal was to write a program that plays the classic arcade game "Asteroids", and the entry with the highest score wins.

Now, there were many different approaches, but the really clever ones involved figuring out the state of the internal timer of the game, which is used for random number generation. Once the player program managed to do that (it only needed to observe a handful of events that depended on the RNG), it was able to predict the course of the game perfectly (where asteroids will appear at the start of the level, what speed and direction the fragments of a destroyed asteroid will have, whether it's safe to hyperjump and where the players ship will end up, etc). Such player programs would fire at objects only popped into existence when the shot arrived, and use the hyperspace button to get into optimal firing positions instead of just as an emergency measure.

List of 67 messages in thread
TopicAuthorDate
Random numbers            01/01/70 00:00      
   How random?            01/01/70 00:00      
   extract?            01/01/70 00:00      
      Time for Google            01/01/70 00:00      
      Extract            01/01/70 00:00      
   you can't            01/01/70 00:00      
      a very good way to get random numbers            01/01/70 00:00      
      Interesting anecdote regarding timers:            01/01/70 00:00      
      Periodicity            01/01/70 00:00      
   Just curious...            01/01/70 00:00      
      Didn't search first!            01/01/70 00:00      
         New Information not searchable            01/01/70 00:00      
            Using life itself as part of its computational matrix...            01/01/70 00:00      
               Sure it is            01/01/70 00:00      
         Show me any real new thread...            01/01/70 00:00      
            But...            01/01/70 00:00      
               It really means...            01/01/70 00:00      
                  No "Come In!", but a "Go Home!"            01/01/70 00:00      
                     Exclusive information...            01/01/70 00:00      
                        Thanks...            01/01/70 00:00      
                        First and ONLY Time I reply to this            01/01/70 00:00      
                           Completely ridiculous might be a bit strong            01/01/70 00:00      
                           Lazyness...            01/01/70 00:00      
                              ...is already ignored            01/01/70 00:00      
                                 But we restrict ourselves!            01/01/70 00:00      
                                    No, you are restricting the definition of "help"            01/01/70 00:00      
                                       Your propaganda again...            01/01/70 00:00      
                                          People ARE posting code snippets etc            01/01/70 00:00      
                                             Come on, how many do so?            01/01/70 00:00      
                                                Do what?            01/01/70 00:00      
                                          The limiting factor            01/01/70 00:00      
                                             Mixing subjects            01/01/70 00:00      
                                                Not a valid answer            01/01/70 00:00      
                                                   Are we poluting this thread?            01/01/70 00:00      
                                                      Yes, but Roberto has gone already...            01/01/70 00:00      
                              true for good schools, but not for diploma mills            01/01/70 00:00      
                     Balance            01/01/70 00:00      
                        Warding people away is no good policy either            01/01/70 00:00      
                           Bully for seeing problems with negative votes???            01/01/70 00:00      
                              Its his will            01/01/70 00:00      
                              Its just a biginning!            01/01/70 00:00      
                                 Still extrapolating            01/01/70 00:00      
                                    Relativity?            01/01/70 00:00      
                                    Extrapolating What            01/01/70 00:00      
                                       Not a valid conclusion!            01/01/70 00:00      
                                       Still extrapolating            01/01/70 00:00      
                           Wrong link?            01/01/70 00:00      
                              link to link            01/01/70 00:00      
                                 But nothing about fear of 8052.com?            01/01/70 00:00      
                                    At least,...            01/01/70 00:00      
   This method might work...you can try it....            01/01/70 00:00      
      Unnecessary complication!            01/01/70 00:00      
         Watch out for distribution problems for small ranges            01/01/70 00:00      
         Yes..But for added randomness, use the table            01/01/70 00:00      
            Incorrect - the table adds nothing!            01/01/70 00:00      
               Quality often important even for simple devices            01/01/70 00:00      
                  can be dangerous            01/01/70 00:00      
                     Bus arbitration needs a lot            01/01/70 00:00      
            HUH????            01/01/70 00:00      
      he can't            01/01/70 00:00      
      Modulating the /INT0 input by a simple noise generator            01/01/70 00:00      
         Post-processing needed            01/01/70 00:00      
            What interrupt?            01/01/70 00:00      
               Both interrupt or gating possible            01/01/70 00:00      
                  Full agree with everything you wrote!            01/01/70 00:00      
         Addendum...            01/01/70 00:00      
   Google as a resource?            01/01/70 00:00      

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