Alt-BEAM Archive

Message #05296



To: beam@sgiblab.sgi.com
From: Sean Rigter rigter@cafe.net
Date: Wed, 14 Jul 1999 21:50:41 -0700
Subject: [alt-beam] Re: automatic pnc


Hi Bruce,

I'll try this but same idea using 3 diodes to kill 3 twin processes with a
fourth diode to catch pulses spaced at interval 3 ie output 1 to input 4
should catch all combinations quickly. Alternately 1 to 3 and 2 to 5 should
catch them slower with fever parts.
BTW it is perfectly ok to terminate the Nv bias point resistors not to 0V but
to 5V. Processes would be active high and normally low when inactive. The
advatage of this is to be able to use a 74HCT14 with it's thresholds shifted
towards 0V, making it possible to use higher Vf LEDs in an OR gate with the 1K
resistor to 0V. Basically every thing get's turned upside down but it still
works as a ucore. Never hear much about this positive logic option though. Any
thoughts or history?

enjoy

wilf

Bruce Robinson wrote:

> Wilf Rigter wrote:
> >
> > Hello David,
> >
> > I feel a little guilty knowing that Bruce has invested significant effort
> > in his cold start circuit design but it all part of the learning game
> > so here is a some friendly competition:
>
> Ha! Knew you'd join in sooner or later, Wilf.
>
> The effort was mostly mental, and it helped me understand Nu's and Nv's
> better, so nothing is wasted. BTW, I don't know if I posted it or not,
> but I came up with a simpler 2-inverter "cold start" circuit, with
> significantly fewer components. Still not as clean as yours, though.
>
> But, umm, tell me. How would your circuit look for a 6-Nv microcore?
> .
>
> I'm sure that'll get me put in my place pretty quickly.
>
> Take care, all.
> Bruce


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