I seem to recall Hewlett-Packard used to make probably in the late 1980s, portable typewriter-like things with a keyboard and a roll, but instead of a printing head, a plotter capable of using four colour pens to "print" the letters typed on the keybo...

[michaelporter@ottawa.place]

@riley I own a Wacom tablet and an iPad, so you got me curious (links below, ff your’e interested).

It looks like the surface does all the work in detecting the pen and its position. The Wacom basic styluses have an LC circuit in them, tuned to a particular frequency (or range of frequencies, rather). I’m sure Apple uses a different frequency, but wouldn’t be surprised if the new crop of Wacom wannabes (that have arisen since the expiration of the relevant patents) use the same frequency as Wacom so as to take advantage of compatibility (sell pens to Wacom owners, sell tablets to people who have pens, etc. Total speculation on my part there, though.

More bells and whistles, in the form of accelerometers and gyroscopes you mentioned, require power, so the Pencil needs to be charged while my Wacom stylus does not.

My Wacom tablet does not have a raised bevel, so either device would be fine for laying a piece of paper on. Seeing the effect of that paper on the capacitance will have to wait until after I walk my dog

Links that helped me (not an endorsement, just the first ones I came across. If you know of better ones I’d love to have ‘em):
https://essentialpicks.com/how-apple-pencil-work/
https://essentialpicks.com/emr-stylus-how-wacom-pens-work/

[michaelporter@ottawa.place]

@riley Whoops, I almost replied with a rational comment

For the archives:
Pushing precision past 3 sig figs is probably unnecessary for most applications.

[riley@toot.cat]

@MichaelPorter So, it's exactl the sort of unnecessary fanciness that Elves would do if Elves made slide rules.

[riley@toot.cat]

@MichaelPorter Then, Apple's thing is probably not Wacom-compatible. The Pencil notably includes a small processor and does quite a bit of computation on board, although the main purpose of this computation is to track the Pencil's gyroscopic location and the tip's pressure, so fusing that data with location gathered on the panel's side would not be entirely out of the question. Still, I doubt Apple would have split it up like that.

Also, Pencil does not interact with the capacitive touch panel (other than by sensing the pressure and angle of its tip being pressed against the glass of the screen). It strictly requires another, further, layer of electronics to function. This is also convenient for reliably telling finger-touches apart from Pencil-touches, which typical Android devices with hacked-up capacitive styli just can't do.

[riley@toot.cat]

@MichaelPorter Oh, btw, I'm pretty sure that the Wacom tablet has no problem at all with a single sheet of paper, for backwards compatibility reasons. Wacom's graphics tablets didn't exactly fall out of a coconut tree; instead, they developed from, and used to compete against, an older similar class of devices called 'digitisers', whose major use case was tracing pre-drawn drawings from paper into a computer.

[riley@toot.cat]

@3rz Danke!