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From: bryce@hoser.berkeley.edu (Bryce Nesbitt)
Newsgroups: comp.sys.amiga
Subject: Re: A-500 Parallel port differences (A500 user manual, really)
Message-ID: <21557@ucbvax.BERKELEY.EDU>
Date: Mon, 2-Nov-87 05:08:57 EST
Article-I.D.: ucbvax.21557
Posted: Mon Nov  2 05:08:57 1987
Date-Received: Thu, 5-Nov-87 23:21:08 EST
References: <11998@decwrl.DEC.COM> <2662@cbmvax.UUCP>
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: University of California at Berkeley
Lines: 41
Summary: How to blow up your A500 power supply...

In article <2662@cbmvax.UUCP> grr@cbmvax.UUCP (George Robbins) writes:
>In article <11998@decwrl.DEC.COM> kruger@16bits.dec.com () writes:
>> That power supply is wimpy,
>> and it running on the edge.
>
>The power supply for the A500 is fairly conservatively rated.  It is certainly
>not "on the line".  Most of the problems we've seen have been mechanical in
>nature - pieces that don't stay where they should when you drop the thing.

One thing George did not mention was ventilation.  The power supply case
is such that leaving it on a nice insulating carpet could contribute to
bad news.
The manual does not have a warning about this.  Or perhaphs I should
say that it does not have a *WARNING*.
While I'm picking nits at that manual, it says nothing about static
or pluging the computer brick in first, so you have a discharge
path.

Now if only the power switch was on the side of the brick that the
*computer* end of the cable exits :-(.


>The reason that we didn't put hundereds of amps of 5 volts on the parallel
>connector was that we wanted it to be safe to plug in any device attached
>to an IBM printer cable.

Sigh.
In my mind I is an indication of the ultimate failure of the expansion
scheme that so many things hang off the serial and parallel ports.
However as general purpose cheap I/O hooks it's hard to beat a
bi-directional parallel port *with power*. 

Even with the limited +5 on ATUOFDXT dealers need to be careful in
selecting cables to avoid bad Ring Indicator problems.  :-(
(Is that cable "Amiga certified"? :-)

|\ /|  . Ack! (NAK, SOH, EOT)
{o O} . bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce
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  U	"You can count how many seeds are in an Apple, but not how
	 many Apples are in a seed." -Ken Kesey