# Instruction Stack

I was playing with the idea of having an Instruction Stack.
#InstructionStack
#ShiftRegister
#UniversalPatternGenerator
#BeyondFiniteStateMachine

A very simple version would contain one-bit “instructions” (eg, next ball is red or blue). Having an arbitrarily high instruction stack could thus generate arbitrarily long patterns.
On the standard board as delivered this doesn’t really work as it needs lots and lots of gear pieces, but each aspect can be demonstrated on a standard board.

Illustration of Stack

Diagram shows an extensible “stack” or register of one bit “instructions”. Each ball that goes through sets the value of each layer to what the one above had been.
The layers can be interpreted as a set of one bit “instructions” that work their way down in order to the bottom.

Tiny stack on Standard Board (but with extra pieces)- to generate a desired pattern

This includes a terminator. Choice of lever determines the colour of first ball. Choice or remaining balls is determined by which direction each one-bit register in the stack is set to.

Given a large enough board and sufficient pieces, this could clearly be made into a device to create any pattern of balls.
Challenge: other one-bit uses - Can such a simple stack be used to drive other kinds of problem solving?
Challenge: Two-bit instruction stack. Is it possible to create a similar “instruction stack” but that can ripple two bits of information down the stack (which could then in principle drive more interesting problem solving logic?)

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