# How good of a computer could be designed without electricity? **URL:** \ **Category:** Factual Questions\ **Created:** [March 8, 2010, 4:10am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690 "2010-03-08T04:10:35Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![No\_Wikipedia\_Cites](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@No\_Wikipedia\_Cites](https://boards.straightdope.com/u/No_Wikipedia_Cites)\ **Post date:** [March 8, 2010, 4:10am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/1 "2010-03-08T04:10:35Z")
Ok, if today an excellent batch of experts were stranded on a deserted island, but had bunches of Radio Shack surplus parts, everything except electricity, how good of a computer could they build? I presume it could not be digital? What could the functions be of the computer? What could it do, I mean? ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [March 8, 2010, 4:11am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/2 "2010-03-08T04:11:59Z")
It could certainly be digital as opposed to analog, in the sense of using discrete as opposed to continuous information values. It just couldn’t be electronic… ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [March 8, 2010, 4:38am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/3 "2010-03-08T04:38:02Z")
This was probably the most sophisticated mechanical computer ever made: [Difference engine - Wikipedia](http://en.wikipedia.org/wiki/Difference_engine) You’re not going to make it with coconuts, though. ---
**Author:** ![runcible\_spoon](https://avatars.discourse-cdn.com/v4/letter/r/9fc29f/32.png) [@runcible\_spoon](https://boards.straightdope.com/u/runcible_spoon)\ **Post date:** [March 8, 2010, 4:40am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/4 "2010-03-08T04:40:30Z")
How many experts, and in what? If they’re all hardware engineers, I gotta think they’re not gonna come up with much - that’s a pretty specialized field. But if you get some blacksmiths, some mechanical engineers and so on, you could at least make something on the order of Babbage’s [analytical engine](http://en.wikipedia.org/wiki/Analytical_engine). I don’t think Radio Shack parts are gonna do much good, though - if you’re building a mechanical computer, you need mechanical parts, not electronic ones. A waterwheel and coal-fired machine shop would stand you in much better stead. ETA: to clear up my and \*\*beowulff’s \*\*posts, the difference engine was Babbage’s first computer-like work, but was more of a calculator. The analytical engine was more general purpose, and could be programmed. Either way, I have to think that a more complicated device would be possible, in the absence of electricity, but with it, there’s not much point. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [March 8, 2010, 4:44am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/5 "2010-03-08T04:44:26Z")
Of course if you had the right parts you could make a waterwheel or some other type of turbine to create electricity. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [March 8, 2010, 4:50am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/6 "2010-03-08T04:50:53Z")
[I’d say a pretty good one.](http://www.xkcd.com/505/) ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [March 8, 2010, 4:51am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/7 "2010-03-08T04:51:51Z")
[Turing machine as a mechanical device](http://en.wikipedia.org/wiki/Turing_machine_gallery) ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [March 8, 2010, 5:03am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/8 "2010-03-08T05:03:20Z")
The [Tinkertoy computer](http://www.ohgizmo.com/2006/12/14/the-tinkertoy-tic-tac-toe-playing-computer/) could play Tic-Tac-Toe. (It lacked the voice synthesis module to say, “Strange game.”) ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [March 8, 2010, 8:39am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/9 "2010-03-08T08:39:40Z")
You can model your island economy using a few pipes and a bucket of water. [MONIAC](http://en.wikipedia.org/wiki/MONIAC_Computer). Si ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 8, 2010, 8:53am UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/10 "2010-03-08T08:53:05Z")
> [@sassyfras](#): > > Ok, if today an excellent batch of experts were stranded on a deserted island, but had bunches of Radio Shack surplus parts, everything except electricity, how good of a computer could they build? Are you asking about building a mechanical, non-electrical computer, or are you asking _how good an electronic computer can be built without ever testing it?_ ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 8, 2010, 1:48pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/11 "2010-03-08T13:48:05Z")
Don’t need Radio Shack parts. [Just use rocks.](http://xkcd.com/505/) ---
**Author:** ![No\_Wikipedia\_Cites](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@No\_Wikipedia\_Cites](https://boards.straightdope.com/u/No_Wikipedia_Cites)\ **Post date:** [March 8, 2010, 4:58pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/12 "2010-03-08T16:58:24Z")
> [@Mangetout](#): > > Are you asking about building a mechanical, non-electrical computer, or are you asking _how good an electronic computer can be built without ever testing it?_ The first – it would be a much more suitable question. I am still uncertain as to WHAT these analog computers do, such as the difference engine. What could it do? Mathematical equations? ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [March 8, 2010, 5:26pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/13 "2010-03-08T17:26:54Z")
> [@sassyfras](#): > > I am still uncertain as to WHAT these analog computers do, such as the difference engine. What could it do? Mathematical equations? Any digital computer is essentially doing nothing but math. You see a picture on your screen, but the computer had to crunch a ton of numbers to tell each pixel what color to be. So… 2+2 = 4 = red. If you can do basic logic functions, you can get a computer to do anything. The only limits are processing time and memory capacity. ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [March 8, 2010, 5:30pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/14 "2010-03-08T17:30:51Z")
> [@Joe Frickin Friday](#): > > Don’t need Radio Shack parts. > > [Just use rocks.](http://xkcd.com/505/) [Good idea.](http://boards.straightdope.com/sdmb/showpost.php?p=12199294&postcount=6) ---
**Author:** ![JoelUpchurch](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@JoelUpchurch](https://boards.straightdope.com/u/JoelUpchurch)\ **Post date:** [March 8, 2010, 5:36pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/15 "2010-03-08T17:36:02Z")
As far as I know the simplest analog computer is a slide rule. The simplest digital computer is an abacus. When I took computer solutions of differential equations as a lab course back in the seventies we actually went over and tried out an old analog computer they had in the chemical engineering department. You could actually wire up components to simulate differential equations and see the solution on an oscilloscope. There was actually some very sophisticated analog computers build for bomb sights and gunnery computers. [http://en.wikipedia.org/wiki/Analog\_computers#Electronic\_analog\_computers](http://en.wikipedia.org/wiki/Analog_computers#Electronic_analog_computers) ---
**Author:** ![Capt.Ridley\_s\_Shooting\_Party](https://avatars.discourse-cdn.com/v4/letter/c/cc9497/32.png) [@Capt.Ridley\_s\_Shooting\_Party](https://boards.straightdope.com/u/Capt.Ridley_s_Shooting_Party)\ **Post date:** [March 8, 2010, 5:41pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/16 "2010-03-08T17:41:15Z")
> [@dracoi](#): > > If you can do basic logic functions, you can get a computer to do anything. The only limits are processing time and memory capacity. Not really! ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [March 8, 2010, 5:45pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/17 "2010-03-08T17:45:09Z")
Why hasn’t anyone provided a link to this cool cartoon yet?: [xkcd: A Bunch of Rocks](http://www.xkcd.com/505/) ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [March 8, 2010, 5:46pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/18 "2010-03-08T17:46:28Z")
Not having a computer in the first place to help I don’t think you would consider anything a person can design unaided to be a good computer. You can build logic machines that work without electricity, but there is no way a person will design and build unaided what we consider even a basic home computer. We have come to far for that. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 8, 2010, 7:01pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/19 "2010-03-08T19:01:24Z")
> [@Elendil\_s\_Heir](#): > > Why hasn’t anyone provided a link to this cool cartoon yet?: [xkcd: A Bunch of Rocks](http://www.xkcd.com/505/) Because you didn’t read the whole thread before posting. [sub]just like me.[/sub] ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [March 8, 2010, 7:57pm UTC](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690/20 "2010-03-08T19:57:37Z")
> [@Contrapuntal](#): > > > [@Joe Frickin Friday](#): > > > > Don’t need Radio Shack parts. > > > > [Just use rocks.](http://xkcd.com/505/) > > [Good idea.](http://boards.straightdope.com/sdmb/showpost.php?p=12199294&postcount=6) Normally, it bothers me, too when somebody posts in a thread without reading it first (in fact, there’s a thread going about this right now). But people who post links without explaining what they are just have to realize there’s a sizeable group of Dopers that will _not_ click on the link. [Next page](https://boards.straightdope.com/t/how-good-of-a-computer-could-be-designed-without-electricity/531690.md?page=2)