Alt-BEAM Archive

Message #12405



To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Thu, 23 Mar 2000 16:41:05 -0800
Subject: [alt-beam] Re: Logic puzzle - I need to built a new gate... :-)




Three components are needed as shown below:

enjoy

wilf

<>
> -----Original Message-----
> From: Justin [SMTP:JAF60@student.canterbury.ac.nz]
> Sent: Thursday, March 23, 2000 2:04 PM
> To: beam@corp.sgi.com
> Subject: Logic puzzle - I need to built a new gate... :-)
>
> Hiya,
> For the turning system of a walker I'm designing, I ran into an engaging
> logic problem that I thought I'd share will you (mainly in the hope that
> someone could solve it in a more elegant manner than I have :-).
>
> The problem: (As illustrated below) I have a 4-state truth table and
> want to build a circuit to give these outputs at the appropriate input.
> It's easy if I use an XOR gate, but that would mean adding an entire
> extra IC and I'll be trying to build small. My current solution when
> freeformed would be slightly smaller than a chip, trouble is, it needs
> adjusting when the voltage changes, and the voltage will change a lot
> (solar walker) thus ruling out my design. I have no idea what the
> circuit for an XOR gate is, and I think that could give someone who does
> a big advantage.
> The outputs are connected to the enable pins of a HC240, so that's the
> kind of HIGH/LOW requirements the outputs have to meet.
>
> If someone could see a way to fix the sensitivity of my circuit, that
> would also be great :-)
>
> Here is the guff: << File: puzzle1.gif >>



Attachment: puzzle.gif

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