Cobweb plot on a direct-view storage tube
Like the real tube, nothing fades. Every vector stays lit until you press Page, the Tek key that erases the screen. Changing r draws a new parabola on top of the old one, so you can stack several values and compare them. Where lines overlap they glow brighter, so in the chaotic range the most-visited parts of the curve slowly light up.
Line speed imitates the serial line. Each vector cost about five bytes, so at 2400 baud the terminal drew roughly 50 vectors a second, which is why the cobweb unrolled step by step.
Keys: Space iterate, R run, P page.