Bistable switch

Bistable Switch
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Pattern type	Miscellaneous
Number of cells	43
Bounding box	30 × 48
Static symmetry	Unspecified
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 permanenet 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.

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