VGA Oscilloscope

I couldn't find one, but it would be really cool to make the front end of an oscilloscope that you just need to plug in a VGA monitor. In theory, it shouldn't be too hard with a micro-processor.

After a little (very little) research, the problem I'm seeing is that most microprocessors aren't fast enough to keep up with VGA. What I need is a memory chip to hold the video image and a circuit to convert the image to VGA. This should be it's own test project before taking on the oscilloscope.

Here's instructions from someone who did it with an Arduino: http://www.instructables.com/id/Girino-Fast-Arduino-Oscilloscope/

I see the circuit as having 3 blocks; the scope, the display and the controller. The display circuit would use my idea for driving VGA. The scope circuit would be almost the inverse - it would be active at a very high frequency (but no microcontroller) and automatically take a reading from a ADC every period and write it to a memory chip. The controller would allow the user to manage settings for both circuits and would translate the readings from the scope to the display.

This would have a weird profile that the scope could operate at a very high frequency, but only be able to display ~1fps. But in reality, that's fine because it would work fine with lower range frequencies and be able to be used in a trigger mode for high frequency.

I think this would use DRAM for memory. It might make sense to save the measurements to a smaller, faster space and use an intermediate memory to draw the VGA display.