What's the history behind the play symbol that's still used for controlling audio?
I have heard that the pause symbol is originally from the Japanese character リ which means pause. Is it something similar behind the history of the play symbol or does it comes from a more practical viewpoint similar to how diskettes indicates save?
As you can see from this video, the first cassette player (Phillips 3300) had a triangle indicator for "play," but one which pointed towards the tape itself, not "to the right" from a user's perspective. This corresponded to the motion required to activate playback, and with the actual motion of the play head pushing against the tape Here's a similar button from their Norelco recorder with an icon that points "down" relative to the orientation of the typography on the unit, but again, it's actually pointing in the direction of the play head pressing the tape and of the control which made this happen.
These are the first cassette players, introduced in 1963.
In later cassette tape players, as we all know, a triangle icon pointing "right" relative to the user's view became standard to represent "play", although this direction would typically be at right angles to the motion of the play head.
