Atari ST VGA Cable Procedures

Atari ST VGA Cable Procedures - February 18th 2006 - v1.01.

Taken from https://pest.atari.org/www.logicsays.com/atari/mono/docs/atari_vga.htm by Techie Alison

Introduction.
Atari ST 13-Pin DIN Pinouts.
Standard VGA Pinouts.
Level Adjusting Resistors.
Atari ST to VGA Connector Wiring Assignments.
VGA Common Grounds.
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.

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+2+3	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