A 1973 IBM Selectric typeball recorded dancers' body movements

The sad thing is that I actually vaguely remember them in the office and that earlier, as a kid, few things were cooler than the TV UFO series:

SHADO

SUPREME HEADQUARTERS ......

ALIEN DEFENCE ORGANIZATION ...

SECRET LOCATION .... BENEATH FILM STUDIO

https://www.youtube.com/watch?v=ya_9fUNstvc

Very interesting article, and not just about the dance notation typeball.

The 1962 print ad says "Potential speed becomes practical speed, thanks to a stroke storage system that releases type characters in sequence no matter how fast the typing."

I got curious about the "stroke storage system" - was it mechanical, electronic, or what?

The Wikipedia page has an explanation of this mechanical storage:

> The machine had a feature called "Stroke Storage" that prevented two keys from being depressed simultaneously. When a key was depressed, an interposer, beneath the keylever, was pushed down into a slotted tube full of small metal balls (called the "compensator tube") and spring latched. These balls were adjusted to have enough horizontal space for only one interposer to enter at a time. (Mechanisms much like this were used in keyboards for teleprinters before World War II.) If a typist pressed two keys simultaneously both interposers were blocked from entering the tube. Pressing two keys several milliseconds apart allows the first interposer to enter the tube, tripping a clutch which rotated a fluted shaft driving the interposer horizontally and out of the tube. The powered horizontal motion of the interposer selected the appropriate rotate and tilt of the printhead for character selection, but also made way for the second interposer to enter the tube some milliseconds later, well before the first character had been printed. While a full print cycle was 65 milliseconds this filtering and storage feature allowed the typist to depress keys in a more random fashion and still print the characters in the sequence entered.

https://en.wikipedia.org/wiki/IBM_Selectric_typewriter

An entire article about dance notation and not a single example of what the notation looks like. Disappointing.

That is interesting.

I have an IBM Selectric that I purchased at a thrift store. It is a marvel engineering. It was too much to resist. I have not used it, but I tried it out. It works. It really is a fine machine. I think I will spin it up and exercise it.

I wonder if one of those dance type balls is available any where. I suppose not, but it would be fun to try it out.

Some libraries seem to have copies of the instruction manual (not online, though):

https://www.worldcat.org/title/instruction-manual-for-use-wi...