1. Introduction.
2. Atari ST 13-Pin DIN Pinouts.
3. Scart Euro Connector Pinouts.
4. Level Adjusting Resistors.
5. Atari ST to Scart Connector Wiring Assignments.
6. References.
 

1. Introduction.
================
This document discusses building a colour RGB Scart cable for the Atari ST.  It is relatively straightforward and no more complicated than connecting the right pins together.  The ST's RGB and SYNC signals are a little high being 1v peak-to-peak such that limiting resistors are recommended, they are not wholly necessary though to display a picture just that it may be slightly bright.
 

2. Atari ST 13-Pin DIN Pinouts.
===============================
The following is viewed from the back of the connector, ie. solder connections;
 
            *   *   *   *          4   3   2   1
 
            *   *   *   *          8   7   6   5
 
            *   *   *   *         12  11  10   9
                         
                  *                     13
 
       1 = Audio Output           2 = Composite Video
       3 = General Purpose Output 4 = Monochrome Detect
       5 = Audio In               6 = Green
       7 = Red                    8 = Plus 12-Volt Pullup
       9 = Horizontal Sync       10 = Blue
      11 = Monochrome            12 = Vertical Sync
      13 = GND
 

3. Scart Euro Connector Pinouts.
================================
The following is viewed from the back of the connector, ie. solder connections;
 
          20  18  16  14  12  10   8   6   4   2               
 
     +--------------------------------------------+
      \                                           |
       \   *   *   *   *   *   *   *   *   *   *  |
        \             Male From Behind            |
        |  *   *   *   *   *   *   *   *   *   *  |
        |                                         |
        +-----------------------------------------+
 
          19  17  15  13  11   9   7   5   3   1
 
       1 = Audio Output Right     2 = Audio Input Right
       3 = Audio Output Left      4 = Audio GND
       5 = Blue GND               6 = Audio Input Left
       7 = Blue                   8 = Function Switching
       9 = Green GND             10 = Comm Data 2
      11 = Green                 12 = Comm Data 1
      13 = RED/Chroma GND        14 = Comm Data GND
      15 = RED/Chroma            16 = Blanking
      17 = VIDEO/Sync GND        18 = Blanking GND
      19 = VIDEO/Sync Ouput      20 = VIDEO/Sync Input
      21 = GND
 

4. Level Adjusting Resistors.
=============================
Resistors of 150ohms to be placed on the Red, Green, and Blue lines.  75ohm resistor to be placed on the Vertical Sync to Fast Blanking line.
 

5. Atari ST to Scart Connector Wiring Assignments.
==================================================
ST Signal Name       13-Pin DIN        Scart        Scart Signal Name
--------------       ----------        -----        -----------------
Audio Output             1              2+6         Audio Input Right+Left
Composite Video          2               20         VIDEO/Sync Input
Green                    6               11         Green
Red                      7               15         Red
Plus 12-Volt Pullup      8                8         Function Switching
Blue                    10                7         Blue
Vertical Sync           12               16         Fast Blanking
GND                     13               21         GND
 

6. References.
==============
http://www.howell1964.freeserve.co.uk/Atari/ST/Atari_ST_Video.htm
 
http://www.algonet.se/~guld1/hardware/atari-scart.html
 
http://www.volny.cz/milarb/Atari/specable.txt