dunno if I am stupid or what...
Apr. 20th, 2006 09:04 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
miriam_eI was mucking around last night still trying to design this frigging VR language and was thinking about datatypes. I want this language to be typeless because humans have better things to do than worry about types. Let the computer worry about that. Anyway I was thinking about fixed point arithmentic like we used to do in the old days before floating point units became a part of all desktop computers. Then I somehow got distracted... (what, me?) and was thinking about how logic gates are actually designed. Nobody thinks about this stuff anymore. This is a waste of time, right? I try to shake myself out of it but my mind is like a dog snuffling in the undergrowth and I feel like some part of me is shouting at it, "Come out of there, you're wasting time. Hurry up. Look, I'm leaving without you..." But no use. It wouldn't budge. It had found something. It was old and smelly and probably no use at all, but it was kinda odd.
I'd noticed that a see-saw is an inverter: You push one end down and the other end pops up.
I'd also noticed it is easy to put two see-saws side by side so that something on one end of both forms a NOR gate: Push one see-saw down and it lifts the thing on the other end, push both see-saws down and it lifts the thing on the other end. The thing on the other end is only down if both see-saws are up. If down is 1 and up is 0, the two see-saw ends you push are A and B, and the thing on the other end is C then:
A NOR gate is one of those magical devices -- you can build any other logic gate from it.
I suddenly realised I could build a computer from paddlepop sticks.
I'd noticed that a see-saw is an inverter: You push one end down and the other end pops up.
I'd also noticed it is easy to put two see-saws side by side so that something on one end of both forms a NOR gate: Push one see-saw down and it lifts the thing on the other end, push both see-saws down and it lifts the thing on the other end. The thing on the other end is only down if both see-saws are up. If down is 1 and up is 0, the two see-saw ends you push are A and B, and the thing on the other end is C then:
| A | B | C |
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 0 |
A NOR gate is one of those magical devices -- you can build any other logic gate from it.
I suddenly realised I could build a computer from paddlepop sticks.
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no subject
Date: 2006-04-20 01:12 pm (UTC)no subject
Date: 2006-04-20 10:22 pm (UTC)And I woke up this morning still thinking about it! Can't get the blasted thing out of my mind. I drew out a simple device that adds two numbers together entirely built out of these little see-saws. I also realised that using a wind-up mechanism you could run stored programs on such a device.
Wouldn't that look like something!
Lady Ada is reborn
Date: 2006-04-21 01:12 am (UTC)Perhaps you are descended from the Countess of Lovelace... <grin/>
Re: Lady Ada is reborn
Date: 2006-04-21 03:06 am (UTC)I always admired her. She, far more than Babbage worked on the programming of the difference engine. She even speculated that such general purpose calculating machines could be used for music one day. How amazing is that! She is one of the people I'd love to travel back in time to see. I'd show her a Palm computer playing an mp3 of music constructed of a mix of sampled voices and instruments and synthesiser sounds, then I'd show her the Wikipedia entry about her also on the Palm. ( http://en.wikipedia.org/wiki/Ada_Lovelace by the way.)
Other people I'd like to visit would be:
- Leonardo da Vinci (I'd show him airplanes and helicopters and diving equipment),
- Jules Verne (submarines, space ships, maps and pictures of the underground portion of Vancouver),
- H.G. Wells (space ships and the cute Mars robots, the hydrogen bomb, and the time machine itself of course),
- Alan Turing (my Palm again, and pictures of gay pride marches, also I'd tell him about the yearly Loebner Prize (Turing Test), and the internet)
- Radclyffe Hall (a bundle of Karin Kallmaker's lesbian romances which all end happily ever after)
I'd be busy wouldn't I. :)
no subject
Date: 2006-04-20 02:32 pm (UTC)As for NOR gates, yep, they're logically complete, which is very nifty. It's the only operator that is logically complete by itself; others need two or more to affect any other operation.
Additionally (so I'm told), NORs are easy/small/cheap/faster-running to implement in silicon...so many packages that appear to be AND-gates or some logical sequence (say, a large formula, collapsed with the aid of Karnaugh maps), are constructed a bunch of NOR gates cleverly arranged.
no subject
Date: 2006-04-20 11:02 pm (UTC)As I mentioned to Sandra above I drew out a quick design for an adder using the little levers. It is remarkably simple. I thought it would be a very complex affair, but it took astonishingly few levers. Also I can see in my head a device driven by windup clockwork to run stored programs.
I'm going to have to build some of this!
I wonder if this is anything like the tic-tac-toe (noughts and crosses) hand-cranked computer Danny Hillis (Thinking Machines Corp, the Connection Machine, Applied Minds) build out of fishing line and wooden tinkertoys, now in the Boston Computer Museum.