Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!cs.utexas.edu!sun-barr!oliveb!tymix!tardis!jms
From: jms@tardis.Tymnet.COM (Joe Smith)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Multi Par: Ports
Summary: A/B/C switch OK
Message-ID: <531@tardis.Tymnet.COM>
Date: 22 Aug 89 03:07:27 GMT
References: <3761@m2-net.UUCP>
Reply-To: jms@tardis.Tymnet.COM (Joe Smith)
Organization: McDonnell Douglas Field Service Co, San Jose CA
Lines: 24

In article <3761@m2-net.UUCP> ba@m-net.UUCP (Bill Allen) writes:
>3)  Cheap A/B/C switches?
>Does everyone agree it's a good idea to do a cold start
>before/after A/B/C switching?  If so, then A/B/C switches
>aren't the answer.

The advice I've heard is:
  For devices that get their power from a multipin connecter, it is dangerous
  to plug/unplug the device with the power on.  You can kill the delicate
  electronics when not all the pins are making contact.  For instance: +5v
  is connected but the only path to ground is thru a data line.

  However, A/B/C switches that switch all 25 pins on the parallel port are
  OK, since power is applied and removed cleanly.

The DigiView manual says to not unplug the video digitizer with power on.
They recommend an A/B switch that switches all 25 pins to switch from
digitizer to parallel printer while running DigiView.

-- 
Joe Smith (408)922-6220 | SMTP: JMS@F74.TYMNET.COM or jms@tymix.tymnet.com
McDonnell Douglas FSCO  | UUCP: ...!{ames,pyramid}!oliveb!tymix!tardis!jms
PO Box 49019, MS-D21    | PDP-10 support: My car's license plate is "POPJ P,"
San Jose, CA 95161-9019 | narrator.device: "I didn't say that, my Amiga did!"