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A '''boat-bit''' is a binary digit represented by the presence or absence of a [[boat]] next to a [[snake]] (or other suitable object, such as an [[aircraft carrier]]). The bit can be toggled by a [[glider]] travelling along a certain path. Such an object is sometimes called a '''snake-bit''', although that name is less sensible because the snake can easily be replaced by other objects.<ref>{{ | A '''boat-bit''' is a binary digit represented by the presence or absence of a [[boat]] next to a [[snake]] (or other suitable object, such as an [[aircraft carrier]]). The bit can be toggled by a [[glider]] travelling along a certain path. Such an object is sometimes called a '''snake-bit''', although that name is less sensible because the snake can easily be replaced by other objects.<ref>{{CiteLexicon|file=lex_s.htm#snakebit|name=Snake-bit|accessdate=June 3, 2009}}</ref> A correctly timed glider on a crossing path can detect whether the transition was from 1 to 0 (in which case the crossing glider is deleted) or from 0 to 1 (in which case it passes unharmed). Three gliders therefore suffice for a non-destructive read. | ||
The mechanisms involved in reading and writing a boat-bit are shown in the diagram below. The bit as shown in is the 0 state, with no boat present. It is about to be set to 1 by the incoming green glider, and then switched back to 0 again by the red glider. The first crossing glider will survive, but the second will be destroyed. | The mechanisms involved in reading and writing a boat-bit are shown in the diagram below. The bit as shown in is the 0 state, with no boat present. It is about to be set to 1 by the incoming green glider, and then switched back to 0 again by the red glider. The first crossing glider will survive, but the second will be destroyed. | ||
Revision as of 22:54, 16 May 2016
A boat-bit is a binary digit represented by the presence or absence of a boat next to a snake (or other suitable object, such as an aircraft carrier). The bit can be toggled by a glider travelling along a certain path. Such an object is sometimes called a snake-bit, although that name is less sensible because the snake can easily be replaced by other objects.[1] A correctly timed glider on a crossing path can detect whether the transition was from 1 to 0 (in which case the crossing glider is deleted) or from 0 to 1 (in which case it passes unharmed). Three gliders therefore suffice for a non-destructive read.
The mechanisms involved in reading and writing a boat-bit are shown in the diagram below. The bit as shown in is the 0 state, with no boat present. It is about to be set to 1 by the incoming green glider, and then switched back to 0 again by the red glider. The first crossing glider will survive, but the second will be destroyed.
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David Bell found a method of reading the bit while setting it to 0 in January 1997. It works by firing a middleweight spaceship at the boat-bit. If it is already 0 then the middleweight spaceship passes unharmed, but if it is 1 then the boat and the middleweight spaceship are destroyed and, with the help of an eater 1, converted into a glider that travels back along exactly the same path that is used by the gliders that toggle the boat-bit.
Other patterns that can be used to perform the boat-bit reaction include beacon (in its dense phase) and eater 1.
References
- ↑ "Snake-bit". The Life Lexicon. Stephen Silver. Retrieved on June 3, 2009.
External links
- Boat-bit at the Life Lexicon