Re: Ok to leave slave HD cable connected with power off?

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#767

From: Rod Speed
Date: Wed, 30 Jun 2004 01:23

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Phred <ppnerkDELETETHIS@yahoo.com> wrote
in message news:2kdbfmFugvvU2@uni-berlin.de...
> Timothy Daniels <TDaniels@NoSpamDot.com> wrote
>> CJT wrote

>>> Who knows what state they're in when they're unpowered?

>>    1)  Is there a "state" when the circuits are unpowered?
>>    2)  How is the "state" of an unpowered circuit going to
>>         affect the signal passing by?

> Going back a few years, ISTR that the manual for the TRS-80 Model
> I stated that peripherals should all be powered up before (or at least
> simultaneously with) the computer to avoid damage to unpowered circuits.

It was always much more complicated than that.

RS232 was designed right from the start to not only
handle that fine, but to hand shorts in the cable fine too.

In spades with USB and firewire now too.

> Don't ask me why this was recommended; but I *assumed* it
> had something to do with signal current paths that were perhaps
> "open" when they shouldn't have been, and thus more susceptible.

To some extent. Not relevant now tho.

>>    3)  Why don't you try it and see?

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From: "Rod Speed" <rod_speed@yahoo.com>
Newsgroups: comp.sys.ibm.pc.hardware.storage,aus.computers
Subject: Re: Ok to leave slave HD cable connected with power off?
Date: Wed, 30 Jun 2004 11:23:31 +1000
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