stibitz.adder

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Wed Apr 12 07:26:14 2000

What you have done is a 1bit full adder with carry in. It's not quite two
bits and not limited to one bit pair.

Allison




On Tue, 11 Apr 2000, Scott F. Hall wrote:

> For the heck of it, I've tried to design an electro-mechanical binary
> adder that can automatically do the carry of the one that arises in 1 +
> 1 = 10. Of course, you reply, "George Stibitz's already did that in
> 1937 as you see here..."
>
> http://www.toronto-montessori.on.ca/bsutherland/electricity/stibitz.html
>
> But hey: this is retrocomputing, after all, and I'm not trying to
> duplicate Stibitz--my aim is to come up with an electro-mechanical
> binary adder architecture that's even simpler than his 2 switches, 2
> bulbs, 2 batteries, and 2 relays version.
>
> I think I've done it using 3 switches, 4 bulbs, and 1 battery. Yes,
> still eight components but because it lacks the relays, I think it's
> definitely simpler and therefore a kind of retro-breakthrough. And yes,
> mine does carry the one for 1 + 1 = 10. Feel free to try building this
> (or better it if you can with even fewer components).
>
> But I do have a stupid question for everyone that exposes the holes in
> my education: if my adder can successfully do all of the below
> calculations but no more
>
> 0 + 0 = 0
> 0 + 1 = 1
> 0 + 10 = 10
> 0 + 11 = 11
> 1 + 0 = 1
> 1 + 1 = 10
> 1 + 10 = 11
> 10 + 0 = 10
> 10 + 1 = 11
> 11 + 0 = 11
>
> have I constructed a 1-bit binary adder or a 2-bit binary adder?
>
> Thanks,
>
> S.F. Hall
>
Received on Wed Apr 12 2000 - 07:26:14 BST

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