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.
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