Accurate CRT Simulation
In the <i>analogtv.c</i> source code, by Trevor Blackwell (part of XScreenSaver) is this comment [1]:<p><pre><code>    A maxim of technology is that failures reveal underlying
    mechanism. A good way to learn how something works is to
    push it to failure. The way it fails will usually tell you
    a lot about how it works.
</code></pre>
To mimic the image on a 1970s-era colour TV, XScreenSaver uses an accurate DSP simulation of all the analogue circuitry, including bandwidth limits, noise, and distortion. A gigahertz processor is <i>just</i> capable of keeping up with this.<p>[1] In <i>XScreenSaver: a collection of free screen savers for X11 and MacOS</i> by Jamie Zawinski [2].<p>Edit: if you want to read the source code---highly recommended!---retype the address below by hand or you'll become acquainted with jwz's countermeasures.<p>[2] <a href="https://www.jwz.org/xscreensaver/xscreensaver-5.34.tar.gz" rel="nofollow">https://www.jwz.org/xscreensaver/xscreensaver-5.34.tar.gz</a>