What it is and the problem it solves
It is an X-Y position indicator for a display system. It solves the problem of precise, continuous, two-dimensional input for interactive computing.
How it works
It is a wooden shell with two metal wheels that translates physical movement into X-Y cursor position on a bitmapped display.
What works
It works as part of the oN-Line System (NLS), where it enables hypertext navigation, collaborative editing, and windowed displays — all demonstrated live in 1968.
What does not
It does not scale to mass use without integration into a broader interactive system. On its own, it is inert — no operating system, no GUI, no software context.
What it changes
It changes how humans point and select in real time on screen — shifting computing from batch processing to direct manipulation.
Is it worth your time
Yes — if you work on human-computer interaction, interface design, or tech history. It reveals how foundational tools emerge from systems thinking, not isolated invention.