How to construct a NULL MODEM CABLE between the Atari ST and the
 Atari 8-bit(using 850 interface) by Mickey Angell.  I am
 president of GRASP and SysOp of GRASP BBS(804-744-8022). 
 
 I had used phone wire but found that it was too stiff.  The
 stranded cable in the joystick is fragile but it flexes.
 
 You will need the following:

 1. Get a cable with at least 4 wires. I used the Radio joystick
    extension cord.
 2. DB-25 female connector
 3. DB-9  male connector
 4. soldering iron 
 5. solder

    Atari 850 Interface Male Connector

            1 2 3 4 5
           -------------                                        
 DB-9      \ A B C D * /                        BLACK  (A)      
 MALE       \ * * * * /                         GREEN  (B)      
 COMPUTER    ---------                          RED    (C)      
 SIDE         6 7 8 9                           BLUE   (D)      
 
 
 A = Data Terminal Ready                                        
 B = Data Carrier Detect                                        
 C = Transmitted Data                                           
 D = Receive Data                                               
 
 
 
             Atari ST DB-25 Female connector

 
             1 1 1 1 0 0 0 0 0 0 0 0 0                         
              3 2 1 0 9 8 7 6 5 4 3 2 1                         
 DB-25      -----------------------------       BLACK  (A)      
 FEMALE     \ 0 0 0 0 0 A 0 0 0 0 C D 0 /       GREEN  (B)      
 COMPUTER    \ 0 0 0 0 0 B 0 0 0 0 0 0 /        RED    (C)      
 SIDE         -------------------------         BLUE   (D)      
               2 2 2 2 2 2 1 1 1 1 1 1                          
               5 4 3 2 1 0 9 8 7 6 5 4                          
 
 A = Data Carrier Detect                                        
 B = Data Terminal Ready                                        
 C = Received Data                                              
 D = Transmitted Data                                           
 




 I demoed this cable at our usergroup meeting(GRASP).  I hooked
 it p to my ST and my 850 Interface. I used FLASH as my terminal
 program on the ST and Express Cartridge by Orion Microsystems on
 the 8-bit.  I was able to transmit files at 19,200 bps!