You know, I wonder how many of the patents that are critical to the modern TrackPoint IV strategy are actually valid still.
I mean, I see some more recent patents -
US 6198472 for Z-axis on the TP4 (which enables press-to-select and some other gestures, and is critical to a TrackPoint IV clone) (this was for something else),
US 7432908 and
8120578 for the calibration mechanism (which are actually newer patents than the original TrackPoint IV) - but really, other than the Z-axis,
US 5570111 is the critical one here, to at least get the TrackPoint III-era negative inertia transfer function, and it's
expired (if I'm right, it expired 2013-10-29). Even going off of the "you have 21 years after releasing the hardware" absolute safest rule, in case there's other applicable patents, it's 2015-10 - they filed that patent the same month that they released the TrackPoint III in the ThinkPad 755CE.
Seeing that Bill Buxton is working at Microsoft now doesn't give me hope for him being given time to work on further pointing stick development, sadly.
I'm also wondering, given that the actual sensing hardware is being mass-produced... what about an open source firmware for pointing sticks (this is getting
awfully tangential for this thread, mind you)? Could be interesting to have a platform to enable research, play with the transfer function, add functionality that IBM never did...
Also, it is worth noting that Alps has literally every exposed feature of the TrackPoint IV
except for negative inertia in their pointing sticks and associated drivers. The DualPoint on my work Latitude E6430 has press-to-select (meaning they've got a Z-axis), variable stick sensitivity, middle button scrolling (OK, it doesn't work as well as IBM/Lenovo's drivers for that), and all of that jazz... just missing negative inertia.
TrackPoint IV debuted in the ThinkPad 770 (from 1997-10), so even ignoring an exhaustive patent search, we're free and clear (except for possible design patents on the button layout, which are less important (I prefer the ergonomics of the button layout that debuted in the X20, from 2000-09, and was used with minimal modification up through the Ivy Bridge machines (and is apparently re-appearing in the Broadwell machines), but it's not critical, and there's other ways to get those ergonomics)) to clone the crap out of it after 2018-10.