Category:Tektronix

These were plotted using a Tektronix graphics computer^[1] sometime between 1975 and 1978 or so.

All of the designs are based on wide-interval samplings^[2] of sine waves plotted in various different ways. This was a technique I discovered more or less by accident when I mistakenly had the trig functions set to "RAD" (radians) with a plotting program that was designed to work in degrees.

I wrote the plotting program in BASIC, because that's what was available (I think that was probably the first programming language I actually used successfully: I had tried to write in FOCAL-69 in 1972, second grade, but I misunderstood the line-numbering system and my programs all executed out of order. (Also, it's difficult to create any output worth looking at when your output device is a teletype^[3].) I wanted to see what shapes you got when plotting various complex sine functions in polar coordinates.

Footnotes

↑ I think the model number was something like 3017, though Wikipedia indicates that it was the 401x series which was active at that time -- so maybe it was 4017, 4016, 4015? I don't know if there are any photos... (Update: 4015 is starting to ring a bell, so I think that's what it probably was.)
↑ Feel free to ask me to explain what I mean by this.
↑ A VT52 was later added, for those occasions when you didn't actually need a complete printed record of your entire debugging session.