To capture x and y coordinates from an existing drawing, the standard input device is a digitizer tablet (often simply called a digitizer), which maps pen or puck positions to precise digital coordinates.

Introduction / Context:
Engineering and CAD workflows frequently require converting paper drawings into digital geometry. A digitizer tablet, used with a pen or puck, lets users trace features on the paper placed over the tablet, producing accurate x,y coordinates for further processing in CAD systems.

Given Data / Assumptions:

• Goal: obtain precise x,y coordinates from a physical drawing.
• Input device must map physical positions to digital coordinates.
• Device should be designed for tracing and capturing points/lines/arcs.

Concept / Approach:
Digitizer tablets employ sensing grids (electrostatic, electromagnetic) to detect pen or puck location. Software calibrates the tablet to drawing scale, enabling coordinate capture with known accuracy. Functions include point sampling, line following, and snapping to templates. This capability distinguishes digitizers from display-only or general pointing devices.

Step-by-Step Solution:
Place the drawing on the digitizer tablet and secure it.Calibrate reference points to set scale/origin.Use the puck or pen to trace features; the system records x,y coordinates.Import coordinates into CAD for editing and modeling.

Verification / Alternative check:
Digitizers have long been standard in cartography and mechanical drafting for vectorization of legacy drawings, confirming their role as the correct device.

Why Other Options Are Wrong:
Light pen: interacts directly with CRT displays, not paper drawings.DVST: a display technology, not an input digitizer.Trackball: general pointer for on-screen navigation, not precise paper tracing.None of the above: incorrect because the digitizer is correct.

Common Pitfalls:
Skipping calibration leading to scale errors; using low-resolution tablets for fine engineering detail; neglecting repeatability checks during long tracing sessions.

Final Answer:
Digitizer (tablet)