Here is some footage of a few Amiga demos running on Amiga 1200 that is displayed on an oscilloscope. I was so moved by this because this is a really awesome achievement. To use an Oscilloscope for showing Amiga demos is just crazy but a very interesting idea.
The composite signal comes from his Amiga 1200
All of the video signal comes from the composite video signal coming from his Amiga 1200 which is really nice. RetroGameModz shows that this is possible in this video that he uploaded to YouTube.
The signals are fed into a circuit which, with the help of OP-amp based constant current sources, creates linear ramps from the vertical and composite sync signals. Then those two ramps are AC coupled and LP filtered before going into the scope in X/Y mode.
The composite video signal is being inverted and amplified in an OP-amp which is set up as an inverting amplifier, then going through a negative unbiased clamp before going into the Z-input of the scope.
With different trimpots, he writes that he can adjust the width and height of the image as well as the contrast. The brightness of the image is set by adjusting the intensity knob on the scope.
Source: RetroGameModz on YouTube
