From LifeWiki
Jump to navigation Jump to search
x = 25, y = 24, rule = B3/S23 6bo$7bo$5b3o8$16bo$14bobo$10b2o3b2o$11b2o$10bo10bob2o$21b2obo6$bo$b2o$ obo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]
Pattern type Memory cell
Number of cells 11
Bounding box 8×3
Discovered by Unknown
Year of discovery Unknown

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 or eater 1). 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 image in the infobox. 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.

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:

x = 21, y = 23, rule = B3/S23 9bobo$12bo$8bo3bo$12bo$9bo2bo$10b3o9$2o$bo$bobo$2b2o3$14bo$13bobobob2o $14b2ob2obo! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART THUMBSIZE 2 WIDTH 480 HEIGHT 360 Y 7 ZOOM 16 GPS 20 PAUSE 2 LOOP 150 ]]
(click above to open LifeViewer)
RLE: here Plaintext: here

Other patterns that can be used to perform the boat-bit reaction include beacon (in its dense phase), table (if stabilised) and eater 1.


  1. "Snake-bit". The Life Lexicon. Stephen Silver. Retrieved on June 3, 2009.

External links