>>532109990
>>532111107
This is a simple machine that uses circuitry to let three assemblers work to produce red science packs. It's not optimized. I did this in under ten minutes, using only the basic circuits (and a substation, for visual clarity).
The constant combinator at the top sends word of which item to produce to the assembly machines via the arithmetic combinators, which serve only to keep the assembly machines from giving each other orders.
I have enabled both "Set Recipe" and "Read Ingredients". This means the assembly machines will use the signal inputs to decide what to make in that moment (Set Recipe), and that they'll send out a signal along any available pathway to tell other machines what goods they need, and how many of each they need to make 1 unit of whatever they're producing.
They send out a request for iron to make gears, since that's the first signal received. This, I ran through a decider combinator (habit) to the claw, which, being set to "Enabled when Anything > 0" and "Set Filters (whitelist)", will deliver only the goods requested.
I don't want it to empty itself out doing this, so I read the belts and send their total contents as a negative signal against the claw to negate the requested goods signal when items are on the way.
When the steel chest holds more than 100 of any kind of item, it sends a negative signal to the original combinator, eliminating the gear order, allowing the next strongest signal (the red science pack) to come through, at least until gears dip below 100. (This can be easily adjusted using a clock and some arbitrary condition, but I'm keeping it simple here.)
It's crude, but with this, you can turn iron into gears, and copper/gears into red science packs without fretting over gear production outpacing science, or over things like clogged/winding belts, space availability, or needless biter attacks.
You may extrapolate in any direction with this. Logic circuits are the game.