[0.12] Combinator Use & Abuse

[GopherAtl]

With the release of 0.12.0, we're finally getting our hands on combinators, and while some of the most coveted practical applications have to wait until we get additional sensors and circuit-network-enabled devices in 0.13, there's a lot of things, but practical and impractical, that can be done with these new toys. I thought a thread where people could share their inventions and discoveries using these new features would be appropriate!

To start it off, a technical note, a single Decider Combinator set to "=0" is a nor gate. If you know your circuit logic, you'll realise that means deciders, all by themselves, are logically complete. Now, you could make logic gates before, using smart inserters, but such systems tended to be slow and clunky; no more!

Friday Facts #88 showed us a simple timer using combinators, but that's just the tip of the iceberg.

With a Decider being a nor gate, just 2 of them can make a compact and reliable S-R latch...



Those make a basis for any number of other practical systems.

On a whim, I decided to set up a 7-segment decoder, that displays the number of items in a chest. I used... quite a few combinators (93, to be exact, though I'm sure it could be optimized considerably) but it was just a proof-of-concept. It refreshes almost instantly to any change in the quantity in the chest. I only gave it 3 digits, but it's scalable, and you could expand it to as many digits as you liked easily.


(forgive the ugliness, it's not a polished installation in a real build, just a proof-of-concept in a test world)

abridged yet lengthy rough explanation

It would take too many images to show how every bit of this is configured, but I'll give a general explanation instead. Even that's gonna take a while; if anyone has specific questions about how this works, ask and I'll try to answer!

the "input" is iron plates in smartchest near the top-left of the pic; I set it up to fill the smart chest with 999 iron plates from another chest, so it currently counts up from 0 to 999 at the inserters' speed. That's not a limitation, though; the display updating is effectively instantaneous as the chest contents change, regardless of how they change.

The input chest links to a pair of arithmetic combinators; the first divides by a constant 10, and the second takes that output and multiplies it by -10. (division seems to round down, so 10/10 = 1, but so does 11/10, and 19/10, etc)The result of the division is passed down and used as the input value for the next higher digit's logic. The result of the multiplication is joined with the original input value, which effectively subtracts it - so, ex, if the input was 99, divided by 10 gives 9, multiplied by -10 gives -90, then 99 + -90 = 9. That gives us the digit, and is done by just those two arithmetic combinators at the left of each block of logic. That combined value is fed as input to 10 decider combinators, which test if the value is equal to 0, 1, 2, etc. through 9, each outputting a 1 if true on the corresponding numbered signal line. These outputs are all combined, giving me one red cable network with correct signal, 0-9, set to "1" and the rest "0".

That output feeds the input of the 3rd stage, where a series of decider combinators convert those values into segment values. That part is a bit tricky, so I'll walk through an example.

I numbered the segments on the display, starting from the top horizontal one as "0", then the top-left, top-right, middle, etc. For each segment, I basically list out the numbers for which it is on and off; the top segment is off when displaying a "1" or a "4", and on for 2, 3, 5, 6, 7, 8, and 9. So for it, I simply used 2 DCs, testing input signals 1 and 4 and outputting on signal 0 if they were set. That output feeds to the lights, and two lights making segment 0 are set to be on if the value of signal 0 was "2." This is basically an "and" gate. Other segments are more ... bothersome; segment 4, in the bottom-left, is off for 1, 3, 4, 5, 7, and 9, and on for 0, 2, 6, and 8, so in that case I tested for the 4 on values instead of the 6 off values, outputing on signal 4 if the input signal was true, which means the lights for that segment are set to be on if signal 4 is >0. The rest are done basically the same way.

Each block below the first, instead of using a chest for input, takes input directly from the division combinator of the block above it. The system could be scaled up to as many digits as you wanted.

I can't possibly be the only one playing with the new toys, so what kinds of contraptions are other people working on? Big or small, practical or absurd, share it here!

[ratchetfreak]

The wire condition of the smart inserter, pumps can test against other signals

So you can say that a small pump into a cracking plant should only pump when there is more heavy than light oil without any combinators/deciders

[orzelek]

The wire condition of the smart inserter, pumps can test against other signals

So you can say that a small pump into a cracking plant should only pump when there is more heavy than light oil without any combinators/deciders

This is my only and most important use of combinators. No more checking if one of tanks overflows and everything stops. I did use a combinator actually - only pump use would be even more simple

[Sander Buruma]

Before trying to replicate what you made, I'd only made a series of lights that light up sequantially as an input gets higher until it resets and starts over.
<Interlude + Music>
I have it working for 3 digits and any more digits should be no problem.
I'm wondering, are the first 10 DCs of a block really necessary? I've removed them from my circuit and simply converted the input signal directly to 0-7 segment signals and it works all the same just as well. I'm trying to think of a solution that uses less combinators for each digit but nothing has come of that so far.

Heres a video of it working.
http://youtu.be/JbZex775pgU

[GopherAtl]

@Sander Buruma: nope, you're right, I realized somewhat later that those 10 were completely redundant, just never came back to update my post here. I shared a save (at someone's request) on reddit that one with them removed as well as the 3 digits pictured.

[Peter34]

This is my only and most important use of combinators. No more checking if one of tanks overflows and everything stops. I did use a combinator actually - only pump use would be even more simple

I'm still waiting for a Youtube tutorial explaining how to make something like that.

[johanwanderer]

This is my only and most important use of combinators. No more checking if one of tanks overflows and everything stops. I did use a combinator actually - only pump use would be even more simple

I'm still waiting for a Youtube tutorial explaining how to make something like that.

Do you mean something like this?

20150720-01-oil-condition.png

Sorry, no combinators

Basically, I have it set up so that heavy->light will only run if I have more than 1K heavy, and light -> petroleum gas will only run if there are more than 1K light oil. I know this is not exactly the intended result (crack A > B if there are more A than B) but I like having a stockpile of both heavy oil (for lubricant) and light oil (for solid fuel) on hand.

Also my petroleum line is currently disconnected because I'm trying to clean up the extra tank (middle-left)

[Sander Buruma]

I was thinking that perhaps we could hold on to trains by emptying them of fuel and only refilling them later on when we want them to continue, using combinators. However trains retain a bit of fuel from their last unit of fuel consumed, can we solve that somehow?

[MeduSalem]

I was thinking that perhaps we could hold on to trains by emptying them of fuel and only refilling them later on when we want them to continue, using combinators. However trains retain a bit of fuel from their last unit of fuel consumed, can we solve that somehow?

Nope... You'll have to wait for 0.13 when trainstops get smart too. Then you won't have the problem anymore as the upgraded trainstops will offer the option to make a train wait.