back to hardware index Video connections  
Amiga Commodore Hercules Mac S550 Scart SGI VGA
On this page I collect my documentation on video connectors.
Most information was found by own measurement and fiddling around with computer and video equipment, some data was adapted from other sources.

Amiga

 I found the following 8-pin-DIN input connector on an old Amiga-monitor. The same connector can also be found on Commodore monitors.
 
1 2 3 4 5 6 7 8
nc red green blue gnd? gnd H sync V sync

Commodore

 Commodore made many different monitors. The ones I found were quite similiar to the above mentioned Amiga monitor. Here is some more info about the various 1084 models.

Hercules

 This video adapter can be found in ancient 8088, 8086 and 80286 machines, it uses a 9 pin D-subminiature connector. On monochrome systems color-pins 3, 4 and 5 are not connected.
Hercules pin-layout  
1 2 3 4 5 6 7 8 9
gnd gnd red green blue intensity video H sync V sync
Encountered 2 different kinds of Hercules systems which are mutually incompatible: 50 Hz and 60 Hz types. Measured frequencies of two systems:
MS-DOS computer H sync V sync
Tulip 18.41 kHz 50.00 Hz
Philips 21.06 kHz 61.00 Hz
I never succeeded in properly connecting these monitors to other systems (like TV, composite-video, or Apple Macintosh computers). Maybe I have not tried every possibility, but it seems like Hercules monitors are very critical regarding horizontal and vertical frequencies.

Macintosh

 Macintosh monitors can easily be attached to other computers. And macintosh computers can easily be connected to non-Apple monitors. You probably have to experiment a little with the sync-signals, but at least you have to know about the Mac's sense-pins. At boot-time, the Mac looks at these sense-pins and initializes its video-hardware accordingly. By changing the sense-wires, you can easily fool your Mac.
Hercules pin-layout  
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
gndred red Csync S0 green gndgreen S1 NC blue S2 gndsync Vsync gndblue NC Hsync
Code Sense pins Type Resolution
[H x V]		 Vsync
[Hz]		 Hsync
[kHz]		 Bandwidth
[MHz]
1 none - - - -
2 13" B&W, RGB, 12" B&W 640 x 480 66.7 35.0 30.24
3 12" RGB 512 x 384 60.15 24.48 15.667
4 15" B&W portrait 640 x 870 75 68.9 57.28
5 15" RGB portrait 640 x 870 75 68.9 57.28
6 16" RGB 832 x 624 75 49.7 57.28
7 19" RGB 1024 x 768 75 60.24 80
8 21" B&W 1152 x 870 75 68.7 100
9 21" RGB 1152 x 870 75 68.7 100
10 NTSC 512 x 384 60 15.7 12.27
11 NTSC interleave 512 x 384 60 15.7 12.27
12 PAL 640 x 480 50 15.625 14.75
13 PAL interleave 640 x 480 50 15.625 14.75
14 VGA
SVGA		 640 x 480
800 x 600		 60
56		 31.47
35.16		 25.175
36.0
15 13" multiple scan 640 x 480
832 x 624		 66.7
75		 35.0
49.7		 30.24
57.28
16 13" multiple scan 640 x 480
832 x 624
1024 x 768		 66.7
75
75		 35.0
49.7
60.24		 30.24
57.28
80
17 21" multiple scan 640 x 480
832 x 624
1024 x 768
1152 x 870		 66.7
75
75
75		 35.0
49.7
60.24
68.7		 30.24
57.28
80
100

Roland S550 sampler

 I found the following 8-pin-DIN video output connector on the Roland S550 sampler. It looks very much like the Amiga/Commodore-video connector, and the plug mechanically fits. However, notice different pin numbers are used!
 
1 2 3 4 5 6 7 8
+5 V output gnd nc H sync V sync red green blue

Scart interface
scart.gif   Also known as Peritel, this standard provides a cheap multi-signal connector to domestic TVs and other video equipment.

Arrangement 1 was the original and allows for composite video input/output, RGB inputs and stereo audio.
Arrangement 2 was added to take S-Video (S-VHS and Hi-8) inputs. This made pin 15 chrominance and pin 20 luminance.
A recent addition is a ternary level on pin 8 to signal a VCR in wide-screen mode.

Most new TV sets have 2 SCART sockets on their rear. One is usually to arrangement 1 and the other to arrangement 2, but with pin 20 switchable from composite to S-Video luminance. The first can switch from a composite input to RGB input. The second can switch from a composite input to an S-Video input, pin 20 being either composite in or luminance in. Usually the second socket outputs a selectable composite signal on pin 19. That is selectable from off-air, SCART 1, and if they exist front mounted input sockets for a camcorder.
The philosophy seems to be that you connect your satellite receiver or laser disc to socket 1, giving RGB capability. Your video recorder would go on socket 2, and can be S-Video. The video recorder's AUX input can then be fed with whatever you select on the TV. The front mounted sockets for a camcorder are usually phonos for composite video, stereo or mono audio and an S-Video mini-DIN.

SCART arrangement 1 SCART arrangement 2
Pin Signal Signal level Impedance Pin Signal Signal level Impedance
1 Audio output B (right) 0.5V rms <1 kohm 1 Audio output B (right) 0.5V rms <1 kohm
2 Audio input B (right) 0.5V rms >10 kohm 2 Audio input B (right) 0.5V rms >10 kohm
3 Audio output A (left) 0.5V rms <1 kohm 3 Audio output A (left) 0.5V rms <1 kohm
4 (audio) - - 4 (audio) - -
5 (blue) - - 5 - -
6 Audio input A (left) 0.5V rms >10 kohm 6 Audio input A (left) 0.5V rms >10 kohm
7 Blue input 0.7V 75 ohm 7 - - -
8 Function select
(AV control)		 H (9.5-12V): AV mode
M (5-8V): Wide-screen
L (0-2V): TV mode		 >10 kohm 8 Function select
(AV control)		 H (9.5-12V): AV mode
M (5-8V): Wide-screen
L (0-2V): TV mode		 >10 kohm
9 (green) - - 9 - -
10 Comms data 2 ???? ???? 10 Comms data 2 ???? ????
11 Green input 0.7V 75 ohm 11 - - -
12 Comms data 1 ???? ???? 12 Comms data 1 ???? ????
13 (red) - - 13 - -
14 (blanking) - - 14 (blanking) - -
15 Red input 0.7V 75 ohm 15 Chrominance input 0.3V 75 ohm
16 RGB switch control H (1-3V): RGB
L (0-0.4V): Composite		 75 ohm 16 - - -
17 (video in & out) - - 17 (video in & out) - -
18 (RGB switch control) - - 18 - - -
19 Video output (composite) 1V including sync 75 ohm 19 Video output (composite) 1V including sync 75 ohm
20 Video input (composite) 1V including sync 75 ohm 20 Luminance input 1V including sync 75 ohm
21 Common (shield) - - 21 Common (shield) - -


It is quite easy to connect an Apple macintosh to a TV or NTSC/PAL-monitor without any additional electronics. I did it by booting my Mac in video mode 10. The Mac is capable of generating a composite sync signal.
In case you have no Mac, Tomi Engdahl (e-mail Tomi.Engdahl@iki.fi) developed a nice simple circuit that converts two separate Vsync and Hsync signals to a single Csync signal.

Silicon Graphics

 I did not find any seperate sync-signals (Vsync, Hsync, Csync) on my Indy-monitor-cable.
At monitor side there seem to be sense-wires. I compared a 17 inch with a 20 inch monitor.
Pins 3, 4, 5, 9 and 10 do not seem to be important.

SGI pin-layout  
SGI monitor 1 (black) 2 (brown) 6 (white) 7 (grey) 8 (orange)
17 inch gnd gnd not connected gnd gnd
20 inch gnd not connected gnd gnd gnd

With horizontal sync-frequencies below 60 kHz or so, the screen stays black.
I succeeded to drive SGI monitors with an Apple Macintosh Quadra 650 booted in video mode 7 (1024x768 pixels). Other video modes (like low resolution 640x480) appear to fail: SGI monitor plays funny high frequency-tunes but screen stays black.

VGA

 This connector is found on most Intel-PC's. It's quite easy to feed VGA-monitors with Macintosh-signals (or the other way around: attach a Mac-monitor to an Intel-PC). Most modern VGA-monitors are quite tolerant regarding vertical- and horizontal-sync frequencies.
VGA pin-layout  
1 2 3 4,5 6,7,8 9 10,11 12 13 14 15
red green blue gnd gndvideo nc gnd nc H sync V sync nc

On some VGA-monitors (and computers) pin 12 and 15 may be used for power-management.


Pieter Suurmond, 2000