Atari ST VGA Cable Procedures - February 18th 2006 - v1.01.
-----------------------------------------------------------
 
1. Introduction.
2. Atari ST 13-Pin DIN Pinouts.
3. Standard VGA Pinouts.
4. Level Adjusting Resistors.
5. Atari ST to VGA Connector Wiring Assignments.
6. VGA Common Grounds.
7. References.
 

1. Introduction.
================
This document discusses building a monochrome vga cable for the Atari ST.  It is relatively straightforward and no more complicated than connecting the right pins together.
 

2. Atari ST 13-Pin DIN Pinouts.
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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. Standard VGA Pinouts.
========================
The following is viewed from the back of the female connector, ie. solder connections;
 
        *    *    *    *    *            1    2    3    4    5
 
          *    *    *    *    *             6    7    8    9   10
 
        *    *    *    *    *            11   12   13   14   15
 
       1 = RED                    2 = GREEN
       3 = BLUE                   4 = ID2
       5 = GND                    6 = RED GND
       7 = GREEN GND              8 = BLUE GND
       9 = KEY/NC                10 = SYNC GND
      11 = ID0                   12 = ID1
      13 = Horizontal Sync       14 = Vertical Sync
      15 = ID3
 

4. Level Adjusting Resistors.
=============================
Resistors of 150ohms to be placed on the Red, Green, and Blue lines.
 

5. Atari ST to VGA Connector Wiring Assignments.
================================================
ST Signal Name       13-Pin DIN         VGA         VGA Signal Name
--------------       ----------         ---         ---------------
Audio Output             1             
Monochrome Detect        4                5         GND
Horizontal Sync          9               13         Horizontal Sync
Monochrome              11             1+3+5        Red+Green+Blue
Vertical Sync           12               12         Vertical Sync
GND                     13                5         GND
 

6. VGA Common Grounds.
======================
A number of the pins within the female VGA connector need to be shorted to GND.  Pins 4,5,6,7,8,9,10, and 11.  On the actual connector, these are as follows, viewing from behind;
 
        *    *    *    *----*             1    2    3    4    5
                             \
          *----*----*----*----*              6    7    8    9   10
         /
        *    *    *    *    *            11   12   13   14   15
 

7. References.
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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
 
http://www.notator.org/contributions/st_vga.zip
 
http://pinouts.ru/Video/VGA15_pinout.shtml