Re: 6502/6510 ROM selection daughterboard

From: silverdr_at_wfmh.org.pl
Date: Thu, 7 Jun 2012 21:08:31 +0200
Message-Id: <70CBD68C-CFE9-4FD5-9850-9B65A8191A7E@wfmh.org.pl>
On 2012-06-07, at 15:41, Gábor Lénárt wrote:

> while I switched off the power itself (Vcc).  The odd
> thing: the circuit still worked (!!) [..]  In forums people say it's  
> called "parasite power" that it can
> work even without Vcc connected,
> However this clearly shows, that not every IC will "keep in quiet")  
> without
> the Vcc pin either ...
>
> but if someone knows what is this "parasite power thing" I would
> be happy to get to know

I think this is not so uncommon. We had similar situation at work when  
developing an automotive remote controller and wanted to save some  
microamps in order to get longer standby time. Cutting off the power  
in standby mode didn't help a bit. The chip was still draining current  
through functional lines and pretending that nothing happened. I don't  
think this would apply to the old ROMs we talk about but as Ruud and  
Gerrit mentioned, this can't be excluded.

-- 
SD!
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Received on 2012-06-07 20:00:48

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