Display technology: a refresh-vector CRT (vector display) forms images using which fundamental drawing technique?

Introduction / Context:Early computer graphics used two main CRT paradigms: raster-scan (pixel grids) and vector-scan (refresh-vector). Understanding the difference clarifies why certain displays produced crisp lines for CAD and oscilloscopes, while others focused on pixel-based images suitable for photographs and GUIs.

Given Data / Assumptions:

• Vector CRTs direct the electron beam along computed line segments.
• Raster CRTs sweep line by line turning pixels on or off.
• The question asks specifically about the vector technique.

Concept / Approach:In a refresh-vector CRT, deflection circuits steer the beam from one coordinate to another, drawing luminous straight lines. The display list (vectors) is redrawn frequently to maintain persistence (refresh). This method yields exceptionally sharp lines without pixel aliasing, historically favored for CAD wireframes and instrumentation displays.

Step-by-Step Solution:Differentiate raster (grid scan) from vector (directed lines).Identify that vector displays render by moving the beam between points along straight paths.Select the option describing straight-line vector scanning.

Verification / Alternative check:Classic terminals (e.g., Tektronix vector scopes) and early CAD displays are documented as vector-scan devices.

Why Other Options Are Wrong:Option A describes raster scanning. Options B and C do not define an imaging method applicable to vector displays.

Common Pitfalls:Confusing “refresh” with “raster”; vector displays also refresh but without a pixel grid sweep.

Final Answer:It creates images by scanning straight-line vectors between selected points.