Tuesday, August 02, 2011

Minecraft - redstone strangeness

I've already dealt with the basics of how redstone works, but still some oddities can arise.

Let's take a simple system:

From Minecraft
The switch powers the block to which it's connected and this toggles the redstone torch attached to the other side. Power flows from the torch down the bottom set of wires and into the bottom set of pistons. At the same time the torch powers the block above it and the wire resting atop that; this power then flows along the wires to the uppermost pistons. The blocks the wire runs on are themselves powered and these in turn power the middle pistons. As a result all the pistons fire.

Except here's the catch - remove the bottom connecting 'legs' of the wire, but not the ones either side of the torch, and the bottom pistons still fire. Except there's no power running to them. Cut off only the upper wires and results are as expected - only the bottom piston fires. Cut off both sets of legs and no pistons fire.

It gets worse. With power flowing disconnect both pairs of legs. Then reconnect only the upper pair. Despite this being the same configuration as first described only the upper and middle pistons will fire. It requires either the reconnection of the bottom legs or the power to be toggled to fire them all.

There's more fun to be had:

From Minecraft
No switches, no wiring, just redstone torches. The torches underneath the bottom blocks power the lower pistons; the torches at the top power the upper pistons. So what's powering the middle ones? Remove the bottom torches and the lower pistons fail. Remove the top torches and both the middle and upper pistons fail. How is the top torch powering the middle piston?

Two more images:

From Minecraft
Ignoring the layout, when the switch is toggled the torch switches on; this should power the piston next to it. However the result is:

From Minecraft
It powers the middle piston. Now I'm guessing all this behaviour is connected, but I can't see any logic here.