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Post Info TOPIC: 255


Freeman

Status: Offline
Posts: 155
Date: Nov 22, 2005
255
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Why is it that the number 255 holds such importance in the video gaming/electronic world?


I believe that it is a government conspiracy.


If you find any instances of 255 being a 'magic number' in the electronic world, please list it here. I want to get to the bottom of this once and for all. Instances that I found are:



  1. Signature on forum and e-mail -- 255 characters max

  2. Max Level on Gameboy color Pokemon games when using cheats -- 255

  3. Wikipedia article on 255 states
    _______________________________________________________________________________
    255 is a special number in some tasks having to do with computing. This is the maximum value representable by an eight-digit binary number, and therefore the maximum representable by an unsigned 8-bit byte (the most common size of byte, also called octet), the smallest common variable size used in high level programming languages (bit being smaller, but rarely used for value storage). The range is 0 to 255, which is 256 total values.


255 = 28 − 1 = FF16 = 111111112.

For example, 255 is the maximum value



  • that can be assigned to elements in the 24-bit RGB color model, since each color channel is allotted eight bits.
  • of any dotted quad in an IP address.

This number occurs especially frequently in video games when a small number is needed:



  • There are exactly 255 levels in Pac-Man.
  • In The Legend of Zelda, the maximum number of rupees you may have at one time is 255.
  • In Super Mario Bros., the maximum amount of lives you can possess is exactly 255. The game does not check if this number is exceeded; getting another life makes all of them disappear.
  • In Warcraft II, the maximum mana for any magic unit is 255.
  • In Pokemon, although the limit on levels is 100, you can exceed it with a cheat code. Passing level 255 results in the number resetting to 0; however, your stats are not reset.

The usage of 8 bits for storage in older videogames has had the consequence of it appearing as a hard limit in many videogames. It was often used for numbers where casual gameplay would not cause anyone to exceed the number. However in most situations it is reachable given enough time. This can cause many other peculiarities similar to the above listed to appear when the number wraps back to 0.


This number could be interpreted by a computer as -1 if a programmer is not careful about which 8-bit values are signed and unsigned, and the two's complement representation of -1 in a signed byte is equal to that of 255 in an unsigned byte.


Other common numbers in computing include 127, 32767, 65535, 2147483647 and 4294967295 —all of which are 2 raised to a power, minus 1 (a Mersenne number). These represent the upper limit on signed and unsigned 8-bit, 16-bit and 32-bit numbers. The popular Intel CPUs have had registers of these sizes.


As of 2005, 64-bit CPUs are gaining popularity, so expect to see the numbers 9223372036854775807 and 18446744073709551615. 128-bit numbers are larger than can be typically displayed without using scientific notation. 2127 (the maximum value of a signed 128 bit number; in 1's or 2's complement notation, it may be 1 lower) is approximately 1.7014118346046923173168730371588e+38 and 2128 is approximately 3.4028236692093846346337460743177e+38.
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I believe that this Wikipedia article is merely a cover up. If you find any more instances, list them here.



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"Dear humanity, we regret being alien bastards. We regret coming to Earth. And we most definitely regret that the Corps just blew up our raggedy-ass fleet! (Hoo-Rah!)" -- Sergeant Johnson


Master Mage

Status: Offline
Posts: 191
Date: Nov 28, 2005
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WOW that is interesting


i think this deserves a sticky



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