Does someone know how to make a RS-232C cross-cable which conects a Mac and
a PC-AT?

I want to make the cross-cable, but I'm not sure the wiring diagram of the
connection
between a Mac DIN-8 conector and a PC-AT DB-9.
Here are the Pin Assignments for DIN-8 and IBM DB-9. I found them in the
Apple Technical
Information Library.


     Circular 8      Signal                             IBM DB-9
        1       HSKo (+12V)                             1 DCD
        2           HSKi                                2 RxD
        3           TXD-                                3 TxD
        4           GND                                 4 DTR
        5           RXD-                                5 SG
        6           TXD+                                6 DSR
        7           No Wire                             7 RTS
        8           RXD+                                8 CTS
        GND                                             9 Ring Indicator
(not implemented)


I know some electronics and Mac serial port is not RS232C but RS-422.
In particular I'm not sure how to handle the following pins of DB-9,

        DCD
        DTR -- Data Ready?
        DSR
        RTS -- Ready To Send?
        CTS

because I don't know what they mean.


  Circular 8      Signal                             IBM DB-9
        1       HSKo (+12V)                           ?
        2           HSKi                              ? 
        3           TXD-    -----------------------   2 RxD
        4           GND     -----------------------   5 SG    
        5           RXD-    -----------------------   3 TxD 
        6           TXD+                              ?
        7           No Wire                             
        8           RXD+                              ?  
        GND                                            

Any comment or sugestion is welcome.

Regard.
--
Tatsuaki Wada
       Dept. Electrical and Electronic Engineering
       Ibaraki University
       4-12-1 Nakanarusawa, Hitachi, 316, Japan.
e-mail:  wada@ee.ibaraki.ac.jp