Atari ST VGA Cable Procedures

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.

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