Article 402 of comp.sys.apple2.programmer:
Newsgroups: comp.sys.apple2.programmer
Path: caen!uwm.edu!cs.utexas.edu!uunet!tarpit!bilver!vicstoy!aphelps
From: aphelps@vicstoy.UUCP (Austin Phelps)
Subject: Re: Apple ][c serial port pinout needed
Message-ID: <1993Jul17.165610.2364@vicstoy.UUCP>
Organization: vicstoy public access Unix, Orlando, FL
References: <222li5$m9u@usenet.INS.CWRU.Edu>
Date: Sat, 17 Jul 1993 16:56:10 GMT
Lines: 36

In article <222li5$m9u@usenet.INS.CWRU.Edu> bt047@cleveland.Freenet.Edu (Eric P. Godfrey) writes:
>
>	I need the pin diagram of the Apple ][c serial port so
>I can make a modem cable that will work on it.
>	Thanks in advance, Forest

From IIc Reference Manual Vol I

  5.   .1
   4. .2
    1.

Port 2

1 - DTR2B - Data Terminal Ready output
2 - TD2B - Transmit Data Output
3 - GND - Ground
4 - RD2B - Read Data Input
5 - DSR2B - Data Set Ready Input

If you are building the cable for a normal 2400 modem, stright through
will work. for High speed here what the ProTerm manual says.

Computer  Modem
2 -> 2  TD
4 -> 3  RD
3 -> 7  GND
5 -> 6  DSR
1 -> 4  RTS
     Short 4 to 20 DTR

-- 
  Austin Phelps - aphelps@vicstoy.oau.org -or- tf3@delphi.com 
           UUCP - {peora,ge-dab,tous,tarpit}!bilver!vicstoy!aphelps
                - vicstoy Public Access Unix, Orlando FL
                - (407)299-3661  1200/2400/9600 V.32  24 hours  8N1


           Pinout for the Apple IIc Serial port
           ____________________________________
 
     9 pin RS-232         25 pin RS-232          5 pin DIN connector
      (for Apple modem)    (standard modems)      (for Apple IIc)
  
DTR            6               20                           1
TD             9               2                            2
GND     8 & 3 tied together  1 & 7 tied together            3
RD             5               3                            4
DSR            2               6                            5
  
To run AMIE, MCPINIT should remain as is except:
     Serial questions - Apple super serial card
                        enter proper baud rate (bps)
                        serial board is in slot 2
                        all lines are functional
     Screen questions - Apple IIe 80 column board