Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site sdcsvax.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!bellcore!decvax!ittatc!dcdwest!sdcsvax!jww
From: jww@sdcsvax.UUCP (Joel West)
Newsgroups: net.micro.mac
Subject: Re: Comm./Modem Port Warning!
Message-ID: <1323@sdcsvax.UUCP>
Date: Sat, 18-Jan-86 13:27:52 EST
Article-I.D.: sdcsvax.1323
Posted: Sat Jan 18 13:27:52 1986
Date-Received: Mon, 20-Jan-86 05:45:16 EST
References: <527@decwrl.DEC.COM>
Organization: CACI, Inc - Federal, La Jolla
Lines: 18
Summary: Mac plus has no +5V

In article <527@decwrl.DEC.COM>, harrow@exodus.DEC (Jeff Harrow) writes:
> This afternoon I was plugging my Modem port into an extension RS-232 (DB25) 
> cable and, as  I fiddled with the plugs to get them to mate, noticed out of 
> the corner of my  eye  that  the  Mac's  screen  dimmed toward black at one 
> point.  I quickly realized  that this was due to a misallignment of the DB25 
> connectors, where, as I attempted to mate them, the grounded portion of the 
> female plug apparently shorted the +5 provided on the modem cable!!!!!S

Rumor has it, this is why, when the smaller connectors (with 1 less pin)
were chosen for the Mac+, they dropped the +5V pin (Pin 2 on the DB9)
from the connector.

Unfortunately, some peripherals expect this (possibly as a power-on
indicator).  I know the Corvus net won't work.

	Joel West	CACI, Inc. - Federal (c/o UC San Diego)
	{ucbvax,decvax,ihnp4}!sdcsvax!jww
	jww@SDCSVAX.ARPA