Alt-BEAM Archive
Message #05298
To: 'beam@sgiblab.sgi.com' beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Thursday, 15 July 1999 11:05
Subject: RE: automatic pnc
>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:
>
>Although not tested, I think what we have here is an instant auto Pulse
>Neutralizing Circuit (PNC) which will force a single process at power up
and
>any other time at the cost of two 1N4148 diodes. It makes the assumption
>that in a 4 Nv ucore you can have zero, one or two processes active at one
>time. Since the PNC guards against the 2 process condition and since these
>only occur as process pairs in 1 and 3 or 2 and 4, then adding the diodes
>will neutralize the twin processes in 2 or 4 whenever a process is active
in
>1 or 3.
>
> If you wish to guard against the more unusual zero process condition, you
>can combine a Pulse Injection Circuit (PIC ( yikes! no flame wars
please!))
>and the function of 4 red LEDs for indication. This is done with the
>addition of a capacitor and 1K resistor to inject a process into the ucore
>should all processes for some reason die out (unusual). The PIC is actually
>a 4 input AND gate made from the 4 LEDs together with the 1K pull up
>resistor. When all processes die off all four Nv output will go high and
the
>output of the LED AND gate will also go high pulling the 1M resistors of
the
>Nv input high. depending on the value of each Nv time constant one Nv input
>will cross the positive trigger level and the corresponding output will go
>low effectively inject a process into the core. Simultaneously the AND gate
>output drops since there are no longer four high input and the process
>starts to circulate around the core with each LED lighting to indicate the
>Nv which is currently active.
>
>The additional 0.1 capacitor is there to deglitch the circuit Nv but is
>probably not be necessary. Using a single 1K resistor instead of the normal
>4 resistors for LED indication effectively cancels out the 2 additional
>diodes and the capacitor and so it's fair to say that the PNC and PIC
>functions comes for free. In addition, the time constants of the Nvs are
>increased by a factor of 2 or more, since the 1M Nv resistors are
referenced
>to the forward voltage drops of the LEDs (should be about +1.2V) making it
>practical to use smaller resistors or capacitors. The obvious applications
>of voltage controlled Nv time constants was covered earlier in my ETC and
>Servocore articles. The only restrictions for PNC/PIC is a minimum 5V
>powersupply, a 74HC14 (not 74HCT14) chip and relatively low forward voltage
>drop red LEDs. Be sure to terminate the unused inputs of the spare
>inverters to 0V if not used for some other functions (like a 6Nv core).
>
>This circuit comes quite close to my BEAM design target of "a linear
>INCREASE in functionality with a linear REDUCTION in complexity" ie the
>more I throw out, the more it does, which of course I hope is scalable to
>"zero complexity=infinite functionality" (reductio ad absurdum =) .
>
>enjoy
>
> Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> tel: (604)590-7493
> fax: (604)590-3411
>
> <>
>
>
>> -----Original Message-----
>> From: David Perry [SMTP:davidperry@geocities.com]
>> Sent: Tuesday, July 13, 1999 10:54 AM
>> To: beam mailing list
>> Subject: Re: automatic pnc
>>
>> great!
>> Thanks heaps, but i have a few questions.
>> Where do the diode outputs connect to, the input of the microcore
>> inverters?
>> What's that 3rd inverter along, is it the same as the others? Do i just
>> use
>> another 74hc14 for all of them?
>> Great, this will really help, thanks again!!!
>>
>> David Perry
>>
>>
>> Oh and Ben Morgan, when you sent that message EVERYONE GETS IT thats
>> hundreds of people that get an even more cluttered up mailbox.
>>
>> -----Original Message-----
>> From: Bruce Robinson
>> To: David Perry
>> Date: Wednesday, 14 July 1999 11:40
>> Subject: Re: automatic pnc
>>
>>
>> >> David Perry wrote:
>> >>
>> >> But i still can't work out how to make a circuit to automatically
>> >> introduce pulses for one of the following ways:-
>> >> *detect with logic circuits when the microcore has died out and
>> >> restart it OR
>> >> *just introduce a pulse when the circuit starts which i don't really
>> >> want beacuse i don't know why the circuits died
>> >
>> >Hi, David. Here's my cold-start circuit which I posted a while back. It
>> >starts your microcore up with one pulse, period. No waiting while extra
>> >pulses die out, or any of that stuff.
>> >
>> >This one is 100% guaranteed. I have been experimenting with another
>> >circuit which does the same thing, but only uses two inverters. It's
>> >worked perfectly for me so far, just have to get it into GIF format.
>> >
>> >Finally, I think I can adapt this circuit to figure out if your
>> >microcore has gone dead. Essentially, there would be one neuron with a
>> >very long delay, that would be triggered by one of the neurons in your
>> >microcore. As long as a pulse kept coming around to trigger it, the
>> >delay neuron would keep getting reset. However, if all your pulses died
>> >out, the delay neuron would eventually time out and send out a signal,
>> >that could be used to start up your microcore again. This one's going to
>> >take some thought, because I don't know how it will behave on startup.
>> >
>> >More to follow.
>> >
>> >Regards,
>> >Bruce
>
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