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From: borton@sdcc3.UUCP (Chris Borton)
Newsgroups: net.micro.mac
Subject: Re: MacPlus 8 Pin to DB25 for in house Terminal Emulation!
Message-ID: <3226@sdcc3.UUCP>
Date: Tue, 15-Apr-86 12:33:33 EST
Article-I.D.: sdcc3.3226
Posted: Tue Apr 15 12:33:33 1986
Date-Received: Thu, 17-Apr-86 05:24:17 EST
References: <1830@dciem.UUCP>
Reply-To: borton@sdcc3.UUCP (Chris Borton)
Distribution: net
Organization: U.C. San Diego, Academic Computer Center
Lines: 43

In article <1830@dciem.UUCP> frank@dciem.UUCP (Frank Evans) writes:
>Does anyone know what would be the correct pin connection for connecting a
>Macintosh Plus 8 Pin to a Db25 male connector which would plug the Mac in 
>to an inhouse network as a Vt100? 
>
>I have been pulling my hair out trying to figure out what the old DB9's 
>connection to a DB25 jack should be.
>
>I reluctantly coughed up $40.00 for Apple's 8pin to DB9. Of course the 
>cable only works my HP laserjet printer and nothing else. I again had to hot 
>wire my own modem cable!!
>
>I called Apple and they said to follow the pin out instructions in the 
>Imagewriter II's manual but this doesn't seem to work or make sense even when I
>traced the leads on the new adapter 8Pin to DB9 cable.
>
>Regardless, does anyone, out there, know what the wiring would be for 
>connectin of the 8Pin to a DB25 for terminal emulation with the Mac Plus??

We've successfully hooked up a Mac+ to our Dataswitch/LAN using Apple's
8-9pin modem adaptor (since it came with the Mac+) and the following scheme
for DB-9 to DB-25: (which I'm using right now)

DB-9			DB-25
----			-----

3----*------------------7 GND
8----|			
5--------->-------------2 TXD
9---------<-------------3 RXD
6----------|||||---->---20 DTR
	   1K Ohm

The 1K ohm resistor is for safety only; the +12V could otherwise ground out and
possibly blow up either the terminal or the Mac's power supply.  This 
configuration works fine for our standard terminal connectors (previously 
Dataswitch, now Ungerman/Bass Net/One).

-Chris
-- 
-------
Chris Borton, UC San Diego Undergraduate CS; Micro Consultant, UCSD
borton@sdcsvax.UCSD.EDU || ...!{ucbvax,decvax,noscvax,ihnp4,bang}!sdcsvax!borton