DLS, the digital logic simulator game | Hacker News Reader

DLS, the digital logic simulator game

makingartstudios.itch.io

121 pointsjsnell35 comments

One of my criteria for assessing a logic simulator is whether it can simulate something nontrivial like an entire CPU, so I was pleased to see there's a 6502 here...

https://github.com/jdryg/dls-schematics/tree/master/6502

...but it seems to be only a 6502-based system showing that you can use a 6502 as an opaque component, and isn't actually simulating its logic with the siulator. On the other hand, the 4004 here is mostly the real deal:

https://github.com/jdryg/dls-schematics/tree/master/i4004

The i4004 was the first real thing I tried to simulate in DLS (I thought it would be easy since it's only a 4-bit CPU... :)). As you said, it's mostly the real deal, since it's missing some components. That's why I added scripting to see if it can make the whole process a bit simpler.

When scripting was implemented, I didn't want to redo the i4004, that's why I started the 6502. And since kernel and basic ROMs were available online, I thought of adding a display to see if I can get some output.

AFAICT, building an entire CPU out of logic gates in DLS is feasible. I just don't have all the time required to do it, that's why I'm currently building (reusable?) parts of a CPU and document the process in the blog. It will be complete some day, but not anytime soon :)

When I was a kid I played a game on the Apple ][ that years later I realized was secretly an introduction to digital design with propagation delay. In the game, little sparks/pulses would travel down wires, and there were various objects (primitive elements) that would manipulate the pulses (and gates, or gates, delays, relays, etc.) If memory serves, each level had a set of pulses that needed to be generated to progress to the next level. I have no idea what it was called and I've looked for it occasionally without success. Anyone know what I'm talking about?

Sounds like it could have been https://en.wikipedia.org/wiki/Rocky%27s_Boots (I played the Commodore 64 version).

I think the successor Robot Odyssey (https://en.wikipedia.org/wiki/Robot_Odyssey) was much more impressive. Same digital logic was used to control robots and solve physical puzzles.

Reminds me of what I've heard about a game called Robot Odyssey (came out in 1984 for TRS-80, Apple II, and DOS).

The author also has a great series of blog posts where he's designing various CPU components in the game (so far the ALU and the register file):

http://dls.makingartstudios.com/categories/circuits/index.ht...

Well, I'm already obsessed with TIS-100. I fail to see how this could be any harder. And then I remember why I hate EE. After all these years, nothing makes any sense, still. Maybe this game will help.

By the way, from the look of it, if you like this game at all, you will love TIS-100, and should totally go buy it.

Zach Barth (maker of TIS-100) did a integrated circuit design game in Flash back in 2009 which might interest you:

http://www.zachtronics.com/kohctpyktop-engineer-of-the-peopl...

It's somewhat more of a game than DLS is at the moment, though working at a much lower level.

I heard that Kohctpyktop was Zach's most brutal game. And between The Guild of Alchemical Engineering, SpaceChem, and TIS-100, that's saying something. The phase: "I can't beat the last level of SpaceChem," has become almost memetic in nature. IIRC, Zach himself couldn't beat it.

I do rather enjoy the "Name your price" mechanism, to where I can get the game for free to at least get a demo, and decide that I want to pay for it later (or if I throw it aside 30 minutes later -- no monetary commitment lost).

I do wonder though, if it might be worth more to just have plain download links with a Donation button. Perhaps someone's already done a study on this. Are people more likely to pay money with the download links behind the "name your price" dialog?

On a side note: the Linux Zip file is a little bit poorly constructed. For Linux, it's usually poor form to not be wrapped up in a dedicated directory. Additionally, the binary isn't marked executable inside the Zip, making the user do it manually instead.

I think the donation button would only work if it was integrated into game (for example a reminder on main menu). Otherwise it would be very difficult to convert the user who is already playing the game for free.

My 4¢:

1. I wouldn't call it a game unless it has a gaming element. Then, I wouldn't value it for its simulation capabilities as much as for its gaming properties (entertaining, addictive, not too easy, not too hard? etc.)

The reasoning is that if you need a logic gate schematic capture & simulator there are tons of professional ones that can be had for free, both open source and commercial.

2. Also, I wouldn't call it an educational game unless it actually teaches the concepts of EE, but judging from the website it doesn't seem to do so. Even the video example has no audio (unless it's a problem on my part) so you either know all the concepts already, in which case this game has no use for you, or you are left scratching your head more often than not. (Why does that rising edge detector thing have 3 NOT gates in series? Why not 1 or 5? and so on.)

3. Manually drawing wires gets tedious very fast. There are many reasons why professionals use HDLs almost exclusively nowadays, but as a hobbyist I can already tell that not having to draw wires (and keeping them ordered after every change) is certainly one of them.

4. The graphics are fine for an educational circuit simulator, but completely miss the mark if this is intended as a game. Look at SpaceChem for an example of a circuit-like game done right. I would love to see a game like that, except based on logic ports instead of automatons.

Hope this is taken as constructive criticism, from someone who is potentially interested in this kind game. Keep up the good work!

Concerning point one, could you please list the alternate software you had in mind? Especially the open source ones. Thanks!

Qucs is the one I've heard of.

https://github.com/Qucs/qucs/

I remember having a similar "tool" when I was a kid (I'm pretty sure it was on MS-DOS, and I suspect it wasn't actually a game but I'm not completely sure, this was a long time ago). Had many kinds of gates, 8-leds, blinkers. I still remember the thrill of building an adder out of simpler gates, only knowing that I wanted something that could "add".

Was it called "Rocky's Boots"? That's what this brought to mind. You could take components from room to room to solve puzzles. As I recall it was kind of self-documenting, in that you just had to figure out from examples what problem they were posing.

edit see https://news.ycombinator.com/item?id=12239171

No, I vaguely recall it being "Electronic Workbench", but googling for it only brings Windows versions, it was definitely a MS-DOS tool. Maybe I can still find the disks somewhere

A bit late but I wanted to mention Logic Friday [1]. The main feature is the generation of simplified circuits that produce the same logic output that a given input. Logic minimization is a hard problem to solve, LF uses espresso [2] to perform it.

1: http://sontrak.com/screenshots.html 2: https://en.wikipedia.org/wiki/Espresso_heuristic_logic_minim...

Looks really nice. What is the gaming component?

I use iCircuit app all the time on my mac, which is a variation on Paul Falstad's circuit simulator (http://www.falstad.com/circuit/).

Thanks!

There are currently no objectives or any game element in DLS. I have some ideas on how this can be turned into a game. Haven't decided which of them will be feasible to implement and be (somewhat) fun at the same time.

If you want a gaming componentes, look at Zachtronics Industries' games, both their paid ones and their old Flash ones. They're great.

Pfff... for the last weeks I was considering designing a game like this (or more exactly, like this may become if the goal is to produce certain waveforms, light up certain LEDs at certain time, power up various stuff in a given order, etc.) and was about to start.

Caramba! Missed again!

You should do it! I doubt I'll decide how to turn DLS into an actual game sooner than you are able to build yours :)

One of my ideas is similar to what you describe but with more complex cases (I can't think of anything simple that will make sense). E.g. controlling traffic lights.

Looks like fun. I wish I could play it, but after manually chmodding and avoiding the tarbomb I get "./DLS: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.21' not found (required by ./DLS)" when I try to run on 64-bit Debian Jessie and "-bash: ./DLS: No such file or directory" when I try to run the other version for GCC 4.9.2. (I have GCC 4.9.3.)

For the first error (`GLIBCXX_3.4.21' not found) try the other Linux version (the one marked as GCC 4.9.3). This was the reason I uploaded it.

For the second error (at least on Ubuntu 14.04) it seems that some dependency is missing but ldd doesn't report it. Under Ubuntu 14.04 ldd maps /lib/ld-linux-x86-64.so.2 to /lib64/ld-linux-x86-64.so.2 but when you try loading the executable this doesn't happen. If this is the case for you, try creating a symlink:

ln -s /lib64/ld-linux-x86-64.so.2 /lib/ld-linux-x86-64.so.2

Hope that helps.

Interesting; how is it possible for `ldd` to report the dependency resolution incorrectly?

Is it possible to fix this with `LD_LIBRARY_PATH`? I would like to avoid running one-off commands on my /lib directory that I don't understand if possible.

A friend of mine made SmartSim, which is very similar. I believe it's in the Raspberry Pi repos.

http://smartsim.org.uk/

See also the examples page for some fun stuff, including a 16 Bit One Instruction Set Computer.

http://smartsim.org.uk/index.php?page=examples

Actually looks like a great game/tool to teach people with rather than using paper examples and asking the teacher if it is correct or not

Another software that employs some of the video game technology such as 3D graphics, animations, and visual effects to let one play with analog and digital electronic circuits is http://www.electricVLab.com.

A Raspberry Pi port would be /really/ valued.

It's at the bottom of my looong TODO list. Hope to find some time to try it out. Don't know if and how it'll work though.

It sure looks like a digital logic simulator, but I don't really see any game elements/mechanics in there?

Guessing he will be adding modes like in kerbal space program which also started out as sandbox only

Yeah, there aren't any yet. As I said in another comment, I have a couple of ideas on how to turn it into a game. Currently I cannot decide which one I'll be able to implement in finite time and if it'll be any fun to play.

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