Bistable switch

	Bistable switch
	<html><div class="rle"><div class="codebox"><div style="display:none;"><code></html>x = 75, y = 61, rule = B3/S23 2bo$obo$b2o11$50bo$50b3o$53bo$52b2o2$45b2o17b2o$46bo17bo$46bobo13bobo$ 47b2o13b2o3$44bo$42bobo$43b2o10bo$54bobo$54bobo$55bo12$73b2o$73b2o4$ 61bo$60bobo$61b2o9$49b2o$48bobo$48bo$47b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] <nowiki></nowiki> <html></code></div></div><canvas width="200" height="300" style="margin-left:1px;"><noscript></html> <html></noscript></canvas></div></html>
	<html><div class="rle"><div class="codebox"><div style="display:none;"><code></html>x = 75, y = 61, rule = B3/S23 2bo$obo$b2o11$50bo$50b3o$53bo$52b2o2$45b2o17b2o$46bo17bo$46bobo13bobo$ 47b2o13b2o3$44bo$42bobo$43b2o10bo$54bobo$54bobo$55bo12$73b2o$73b2o4$ 61bo$60bobo$61b2o9$49b2o$48bobo$48bo$47b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] <nowiki></nowiki> <html></code></div></div><canvas width="200" height="300" style="margin-left:1px;"><noscript></html> <html></noscript></canvas></div></html>
	View static image
Pattern type	Memory cell
Number of cells	43
Bounding box	30×48
Discovered by	Paul Callahan
Year of discovery	1994
Pattern files
Plaintext	bistableswitch.cells
RLE	bistableswitch.rle

The bistable switch is a partial stable reflector discovered in 1994 by Paul Callahan.

Structure

The switch consists of elementary still lifes. More specifically, it uses a block and eater 1, together with a century eater consisting of three eater 1s surrounding a central beehive. In addition to these permanent catalysts, there is an extra still-life to represent the state. This can either be a block or boat, depending on the state.

Reflecting ability

The switch was found when trying to build a stable reflector. When the glider collides with the boat, it is converted into a block and a glider is emitted perpendicular to the incident glider. When a glider (on a different path) collides with the block, it restores the boat, producing an output glider in the same direction to the input glider.

Variants

In June 2013, Ivan Fomichev found a more compact century eater to replace the constellation comprising a beehive surrounded by three eaters:

<html><div class="rle"><div class="codebox"><div style="display:none;"><code></html> #C Century eater replacing a four-object constellation in Paul Callahan's bistable switch #C http://conwaylife.com/wiki/Century_eater x = 30, y = 43, rule = B3/S23 12bob2o$12b2obo2$10b5o$9bo2bo2bo$9b2o3bobo$15b2o16$28b2o$28b2o2$o$b2o$ 2o11$4b2o$3bobo$3bo$2b2o8b2o$12b2o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ THUMBSIZE 2 ZOOM 8 HEIGHT 480 WIDTH 640 ]]<html></code></div></div><canvas width="200" height="300" style="margin-left:1px;"><noscript></html>

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In November 2017, Adam P. Goucher noticed that the century eater could be replaced by a century-to-glider converter, releasing another glider. By using Snarks to channel the gliders, this can be made into a gun as shown below:

<html><div class="rle"><div class="codebox"><div style="display:none;"><code></html>x = 123, y = 93, rule = B3/S23 56b2o$55bobo$49b2o4bo$47bo2bo2b2ob4o$47b2obobobobo2bo32b2o$50bobobobo 35bobo$50bobob2o38bo4b2o$51bo38b4ob2o2bo2bo$90bo2bobobobob2o$64b2o27bo bobobo$55b2o7bo29b2obobo$55b2o5bobo33bo$62b2o$84b2o$85bo7b2o$85bobo5b 2o$86b2o25bo$111b3o$110bo$52b2o15b2o39b2o$49bo3bo15b2o$49b4o$118b2o$ 49b2o45b2o21bo$49b2o45bo22bob2o$97b3o11b2o4b3o2bo$99bo11b2o3bo3b2o$48b o67b4o$47bobo52b2o15bo$48bo52bobo12b3o$45b3o53bo13bo$45bo29b2o23b2o14b 5o$74bobo43bo$75bo42bo$118b2o5$9bo$9b3o$12bo$11b2o$85b2o$85bo$3b2o81b 3o$3bo84bo$2obo$o2b3o4b2o$b2o3bo3b2o$3b4o$3bo15b2o$4b3o12bobo34b2o$7bo 13bo14b2o18b2o$2b5o14b2o14bo$2bo32bo$4bo30b5o14b2o$3b2o35bo13bo$37b3o 12bobo$36bo15b2o$36b4o$34b2o3bo3b2o$33bo2b3o4b2o$33b2obo$36bo$36b2o$ 61bo$61b3o$44b2o9b2o7bo$45bo9bobo5b2o$42b3o10bo$40b3o$39bo$39b2o3$73b 2o$66b2o5bobo$66b2o7bo$75b2o$29b2o$28bobo5b2o24bo$28bo7b2o23bobob2o$ 27b2o32bobobobo$58b2obobobobo2bo$41bo16bo2bo2b2ob4o$37b2obobo17b2o4bo$ 36bobobobo23bobo$33bo2bobobobob2o21b2o$33b4ob2o2bo2bo$37bo4b2o64bo$35b obo71bo$35b2o70b3o! #C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]] #C [[ AUTOSTART ZOOM 4 THUMBSIZE 2 WIDTH 640 HEIGHT 560 GPS 60 ]]<html></code></div></div><canvas width="200" height="300" style="margin-left:1px;"><noscript></html>

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The over-unity variant of the bistable switch has a population of 32, lower than the original variant.

Memory storage

If a glider enters the switch when it is in the wrong state, the glider merely permeates through the device without affecting it. This means that any combination of input gliders, as long as they are sufficiently separated, will not destroy the device. This gives the conduit the ability to store information:

Let the inputs be called SET and RESET. The outputs can be designated SET SUCCESS, RESET SUCCESS, SET FAILURE and RESET FAILURE. The truth table is shown below:

Input	Current state	Next state	Output
SET	0	1	SET SUCCESS
SET	1	1	SET FAILURE
RESET	0	0	RESET FAILURE
RESET	1	0	RESET SUCCESS

gollark: Gotos are *more* prone to that than some other things.

gollark: Well, gotos often just lead to convoluted messy control flow.

gollark: Well, goto bad.

gollark: No. Destroy skeumorphism. ALL MUST BE FLAT.

gollark: I've been there and lived there for a bit, it is definitely a city which exists.

External links

Bistable switch at the Life Lexicon

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