These demos rely on the OS to access sound & graphics, they could not reach the fidelity they do without the OS hiding away much of the file size. You could not do a 4K demo if you had to include the infrastructure to load a modern graphics driver & OpenGL/DX libraries. They are also only small in terms of package size. This demo for example uses about 550MB of RAM while running(Win7x64).

That's not true in the least. We used to do 4K's in dos. Which was a glorified executable loader.

Once your program started executing you were on your own, graphics, sound, memory management, everything. People still managed to get the first level of descent into 4K.

I didn't say you could not make a 4K demo at all. I said you could not make one if you had to include an OS, drivers & DX/OpenGL libraries that most modern 4K demos rely on. You could probably make something like this demo in DOS, but it probably would look nowhere near as pretty.

My point was that modern 4K demos are still fun, but they should not be looked at as though they are great examples of efficient uses of resources. You have to watch out for Man on the Moon Syndrome where people start asking "Why can we get infinite 3D fractal explorations in 4K of space, but Ruby's binary is 10MB!!?".

4K demos in DOS didn't look anything like these modern ones, they were much simpler. They were still very impressive for the time, but the grandparent-post's point is valid.

If you wrote a 4K DOS demo today against modern hardware you wouldn't be able to reach anywhere near the look of these other demos which sit ontop of OpenGL/D3D/Win32 etc, because you'd need to build the equivalent of those API's functionalities into your demo.

Right, but you could do pretty impressive stuff even on a VIC-20.

Stuff like this: http://en.wikipedia.org/wiki/.kkrieger