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vicmodem to rs422 (Mac) conversion. [message #74082] Sun, 26 May 2013 20:53
len is currently offline  len
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Registered: May 2013
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Message-ID: <129@qumix.UUCP>
Date: Thu, 4-Oct-84 18:03:37 EDT
Article-I.D.: qumix.129
Posted: Thu Oct  4 18:03:37 1984
Date-Received: Fri, 5-Oct-84 20:46:19 EDT
Distribution: net
Organization: Qume Corp., San Jose, CA
Lines: 25

This is what I have on paper so far.  Anyone tried something like this
yet?

-----RS422 (+5v line driver/receiver)-----

MAC    function     breadboard       VICMODEM     function
1,3   ground        ground           1,12,A,N     ground
2     +5v           pwr to ic         ------
4      TXD+ -->     3.3k pullup -->     M        data to modem
5      TXD-          ----              ----
6    filtered +12v   ----               10       modem power
7  carrier detect<- LS04-8, 6 to 9, 5 to H,K     carrier detect
8      RXD+          ----              ----
9      RXD- <-- LS04-4 &1k res., 3 to <- B,C     data from modem

		  back of mac
		  -------------
		  \5 4 3 2 1 /
		   \9 8 7 6 /
		    --------

The Macintosh book (red cover) seems to say you can run the RS422 lines
open ended like this.  They talk about doing it with the imagewriter.
I have yet to hook this up and try it.  Also, I want to make sure the
"back of mac" shows the pinouts in the right place.
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