Random-Scan Systems in Computer Graphics MCQ Questions and Answers

1. A random-scan display is primarily optimized to draw
A) Filled bitmaps
B) Line-drawings and vector graphics
C) Photorealistic textures
D) Pixel-based animations
Answer: B

2. Another common name for random-scan displays is
A) Raster displays
B) Bitmap displays
C) Vector displays
D) Pixel displays
Answer: C

3. In a random-scan system the electron beam is directed to follow
A) A raster line pattern
B) Specified vector paths between endpoints
C) A matrix of pixels sequentially
D) Random noise patterns
Answer: B

4. The device that moves the electron beam in a CRT random-scan display is the
A) Phosphor screen
B) Intensity modulator
C) Deflection system (coils or plates)
D) Frame buffer
Answer: C

5. Compared to raster systems, random-scan displays generally require
A) More frame buffer memory
B) Less frame buffer memory but more vector processing
C) Identical memory and processing
D) Only texture memory
Answer: B

6. A major limitation of random-scan displays is
A) Poor line quality
B) Inability to draw straight lines
C) Difficulty in displaying filled areas and complex shaded images
D) High pixel density
Answer: C

7. The persistence of the phosphor in random-scan systems must be
A) Very short to avoid glow
B) Long enough to maintain visibility between refreshes
C) Irrelevant to system design
D) Variable per pixel
Answer: B

8. To avoid flicker in vector displays, the refresh rate must be high or the phosphor persistence must be
A) Very short
B) Matched to refresh exactly
C) Sufficiently long
D) Irrelevant
Answer: C

9. The list of lines/objects to be displayed each frame in a random-scan system is called the
A) Frame buffer
B) Bitmap map
C) Display list
D) Raster table
Answer: C

10. In vector displays, drawing is often performed by a hardware unit called the
A) Rasterizer
B) Pixel shaper
C) Display processor (or vector generator)
D) Texture unit
Answer: C

11. Which algorithm is more directly relevant for random-scan line drawing?
A) Bresenham’s raster algorithm
B) Floating-point line sweep along vectors
C) Pixel convolution
D) Ordered dithering
Answer: B

12. In random-scan systems, clipping of lines is usually performed on
A) Pixel level
B) Frame buffer bytes
C) Vector endpoints (parametric or coordinate clipping)
D) Phosphor intensity
Answer: C

13. Which of the following is stored in the display list for a random-scan device?
A) Color for every pixel
B) Scanline addresses
C) Endpoints and attributes of lines and curves
D) Frame timing signals
Answer: C

14. A key advantage of random-scan displays for CAD applications is
A) Low cost per pixel
B) Very sharp, flicker-free lines suitable for technical drawing
C) Excellent photo realism
D) Simple memory management for bitmaps
Answer: B

15. Which component is NOT essential in a basic random-scan display pipeline?
A) Vector generator
B) Display list memory
C) Large bitmap frame buffer
D) Deflection circuitry
Answer: C

16. The refresh strategy in a vector display typically redraws
A) All pixels sequentially every frame
B) Each defined vector/primitive every frame
C) Only changed pixels via dirty rectangles
D) A compressed image stream
Answer: B

17. In random-scan systems, intensity control for a vector is usually achieved by
A) Arithmetic mean of endpoints
B) Modulating beam current while tracing the vector
C) Changing the deflection coil frequency
D) Adjusting pixel clock
Answer: B

18. If the display list contains N line segments and the refresh rate is R frames/s, the total line-draw operations per second is approximately
A) N/R
B) N × R
C) R/N
D) N + R
Answer: B

19. Which display technology historically used random-scan principles?
A) LCD panels
B) TFT displays
C) Early vector CRT terminals and oscilloscopes
D) LED matrices
Answer: C

20. In random-scan CRTs, beam deflection to draw long straight lines requires accurate
A) Pixel interpolation
B) Analog deflection control
C) Bit masking
D) Frame buffering
Answer: B

21. The term “stroke” in vector displays typically refers to
A) A filled polygon
B) A single pixel change
C) A continuous drawn line segment or curve
D) A scanline blanking event
Answer: C

22. Random-scan displays handle animated vector scenes by updating the
A) Pixel matrix in frame buffer
B) Phosphor chemical composition
C) Display list (coordinates and attributes)
D) DAC sample rate
Answer: C

23. A display list entry often contains which of these attributes?
A) Pixel intensity for entire row
B) Coordinates, color/intensity, and line style
C) Frame timing values only
D) Refresh frequencies
Answer: B

24. To display a curve in a random-scan system, the curve is typically approximated by
A) Pixels in a bitmap
B) Short line segments (polylines)
C) Color gradients
D) Texture maps
Answer: B

25. Which is a typical memory requirement advantage of random-scan displays over raster ones for line drawings?
A) Store color per pixel
B) Store endpoints and attributes instead of per-pixel data
C) Store texture maps
D) Store scanlines for all colors
Answer: B

26. When the number of vectors to be drawn increases, a vector display may suffer from
A) Improved brightness
B) Flicker due to longer refresh time per frame
C) Faster rendering
D) Reduced need for deflection accuracy
Answer: B

27. In random-scan systems, “vector memory” most commonly holds
A) Pixel color map
B) Coordinates and drawing commands
C) Pixel intensities in raster form
D) Analog timing waveforms
Answer: B

28. Which buffering technique is most natural for random-scan systems?
A) Single frame buffer double buffering
B) Double display lists (front and back lists)
C) Tile buffering
D) Pixel caching
Answer: B

29. The major reason vector displays can draw extremely thin lines is that they use
A) Pixel antialiasing
B) Continuous analog deflection, not discrete pixel grids
C) Very high pixel density frame buffers
D) Subpixel rendering
Answer: B

30. For high-quality vector output, deflection circuitry must be able to
A) Store millions of pixels
B) Produce smooth, continuous analog motion of the beam
C) Increase color depth per pixel
D) Reduce phosphor persistence to near-zero
Answer: B

31. Which of the following is used to reduce flicker in vector displays with many vectors?
A) Decrease persistence
B) Prioritize and redraw only critical vectors more frequently (scan scheduling)
C) Reduce deflection accuracy
D) Increase DAC quantization noise
Answer: B

32. A vector generator takes display list commands and outputs
A) Pixel matrix directly
B) Analog deflection voltages and beam intensity control
C) RGB digital pixel values
D) Huffman coded vectors
Answer: B

33. In random-scan systems, the term “stroke fading” refers to
A) Pixel rotation
B) Brightness decay of phosphor strokes over time
C) Curve simplification
D) Loss of endpoint coordinates
Answer: B

34. Which primitive is least natural in hardware for a random-scan device?
A) Line segment
B) Circle arc approximated by math
C) Filled texture map
D) Polynomial curve approximated by segments
Answer: C

35. Which of these is a common display list command type?
A) PutPixel(x,y,color)
B) MoveTo(x,y) / DrawTo(x,y) with attributes
C) BlitFramebuffer()
D) UploadTexture()
Answer: B

36. In a vector system, blink and trail effects are mainly due to
A) Incorrect color mapping
B) Phosphor persistence and refresh scheduling
C) Low resolution
D) Bit depth inadequacy
Answer: B

37. The display processor for vectors often contains a coordinate transformation unit to apply
A) Pixel shading
B) Texture warping
C) Translation, rotation, and scaling to endpoints
D) Gamma correction per pixel
Answer: C

38. The complexity of a display list affects the time to render a frame linearly if
A) Deflection is nonlinear
B) Each vector requires approximately constant time to trace
C) Phosphor persistence is zero
D) The DAC resolution is infinite
Answer: B

39. In random-scan systems, anti-aliasing is typically achieved by
A) Increasing pixel count
B) Varying beam intensity along edges (hardware intensity modulation)
C) Using texture filtering
D) Subdividing pixels into sub-pixels stored in frame buffer
Answer: B

40. For an interactive vector display, the user updates are applied to the
A) Frame buffer directly
B) Display list (or the back display list)
C) DAC registers only
D) Phosphor chemistry
Answer: B

41. Vector displays are especially efficient when representing scenes with
A) Large filled photographic areas
B) A small number of long straight lines
C) High-resolution textures
D) Dense pixel noise
Answer: B

42. Which of the following best describes display list double buffering?
A) Two frame buffers for pixel swapping
B) Two DACs operating in parallel
C) Front display list used for drawing while back list is updated, then swapped
D) Two phosphor types used alternately
Answer: C

43. A vector system must convert high-level primitives (like circles) into
A) Bitmap tiles stored per frame
B) Sequences of line segments or deflection instructions
C) Texture maps uploaded to VRAM
D) Pixel shader programs
Answer: B

44. Which of the following makes random-scan hardware simpler than raster hardware?
A) No need for deflection circuitry
B) No need for a large per-pixel frame buffer
C) No need for a display list
D) No need to modulate beam intensity
Answer: B

45. The maximum number of independent intensity levels in analog beam control is primarily limited by
A) Number of vectors
B) Analog DAC resolution and noise
C) Frame buffer size
D) Pixel clock
Answer: B

46. Which of the following operations is more costly on vector displays than on raster displays?
A) Drawing a single line
B) Drawing a circle as segments
C) Filling large shaded polygons
D) Rotating endpoints
Answer: C

47. In random-scan systems, a priority mechanism in the display list is used to
A) Speed up DAC conversion
B) Determine which vectors are redrawn more frequently to reduce perceived flicker
C) Change phosphor type per vector
D) Reduce deflection nonlinearity
Answer: B

48. The deflection linearity requirement in vector displays is important because nonlinearity causes
A) Faster refresh
B) Geometric distortion of vectors
C) Color shifts
D) Increased pixel density
Answer: B

49. Modern oscilloscopes that draw arbitrary waveforms use principles most like
A) Raster CRT televisions
B) LED displays
C) Random-scan vector CRTs
D) LCD touchscreen arrays
Answer: C

50. Which is true about hybrid systems that combine raster and vector features?
A) They only use vector hardware internally
B) They can use vector hardware for outlines and raster for filled textures
C) They eliminate the need for DACs
D) They cannot handle curves
Answer: B

51. A vector display system that needs to display 200 vectors at 60 Hz must draw how many vector traces per second? (compute)
A) 3,000
B) 6,000
C) 12,000
D) 200
Answer: C
(Computation: 200 vectors × 60 frames/s = 12,000 traces/s.)

52. Which of the following best defines “scan scheduling” in a random-scan system?
A) Scheduling pixel writes to memory
B) Ordering and timing of vector redraws to meet persistence and flicker constraints
C) Prioritizing texture uploads
D) Scheduling OS interrupts
Answer: B

53. If a vector generator traces a vector at constant speed, the apparent brightness along the vector can be made uniform by
A) Increasing pixel count
B) Adjusting beam current inversely with speed (or keeping current constant while speed constant)
C) Changing deflection coil polarity
D) Using a frame buffer intensity map
Answer: B

54. The accuracy of coordinate transformation on a display processor is limited by
A) Phosphor type
B) Numeric precision (fixed-point or floating-point) available in hardware
C) Frame buffer size
D) Pixel clock
Answer: B

55. A display list entry of length 16 bytes can store coordinates and attributes for one vector. If a system can store 1024 such entries, total display list memory is
A) 16 KB
B) 16,384 bytes (≈ 16 KB)
C) 1 KB
D) 32 KB
Answer: B
(Computation: 16 bytes × 1024 = 16,384 bytes.)

56. Which is not typically included in a vector display’s primitive attributes?
A) Color or intensity
B) Line style (dashed/solid)
C) Pixel-by-pixel texture map
D) Z-order or priority
Answer: C

57. The process of simplifying curves into a set of line segments is called
A) Rasterizing
B) Texture mapping
C) Tessellation (or polyline approximation)
D) Gamma correction
Answer: C

58. Vector displays often use hardware addressing modes to speed up drawing. Which addressing mode would help drawing many connected lines?
A) Absolute addressing only
B) Relative MoveTo/DrawTo (delta addressing)
C) Random addressing per pixel
D) Texture addressing
Answer: B

59. For interactive vector editing, minimizing perceived latency usually requires updating the
A) Frame buffer contents directly
B) Back display list and swapping quickly
C) Phosphor chemical reactions
D) DAC lookup tables
Answer: B

60. An advantage of using variable beam intensity in vector displays is to
A) Increase pixel density
B) Simulate anti-aliasing and line shading
C) Decrease DAC resolution
D) Avoid the need for deflection coils
Answer: B

61. If a vector system can trace at most 50,000 vector segments per second and you want 1000 segments per frame, maximum frame rate is
A) 20 fps
B) 50 fps
C) 5 fps
D) 500 fps
Answer: B
(Computation: 50,000 segments/s ÷ 1,000 segments/frame = 50 frames/s.)

62. In vector generators, analog deflection signals are typically produced by
A) Digital pixel lookups
B) DACs converting computed voltages
C) Frame buffer outputs
D) Phosphor excitation codes
Answer: B

63. One common trick to reduce flicker in dense vector scenes is to use
A) Lower persistence phosphors
B) Intensity-based re-prioritization: draw bright/important vectors more frequently
C) Reduce beam speed drastically
D) Reduce DAC resolution
Answer: B

64. The technique of redrawing only part of the display list each frame (to save time) is called
A) Raster clipping
B) Full-frame redraw
C) Partial or selective redraw
D) Pixel caching
Answer: C

65. Which of the following is most important for geometric accuracy in a vector display?
A) Bit depth of frame buffer
B) Linearity and resolution of deflection DACs
C) Pixel clock frequency
D) Phosphor persistence only
Answer: B

66. In a vector system, Z-ordering (which vector appears on top) is typically implemented by
A) Pixel blending in frame buffer
B) Priority flags in display list or multiple passes
C) DAC amplitude modulation
D) Changing phosphor type per vector
Answer: B

67. Which statement about vector vs raster is correct for storage efficiency when representing a simple wireframe model?
A) Raster is always more storage efficient
B) Vector representation usually requires less storage for sparse line data
C) Both require identical storage always
D) Vector requires storing pixel maps for every line
Answer: B

68. If each vector list entry needs 24 bytes and the system stores 4096 entries, total memory used is
A) 96 KB
B) 98,304 bytes (≈ 96 KB)
C) 24 KB
D) 4096 KB
Answer: B
(Computation: 24 × 4096 = 98,304 bytes.)

69. Random-scan systems generally perform which of the following more efficiently than raster systems?
A) Shading textured surfaces
B) Drawing mathematically defined lines and curves
C) Storing photographic images
D) Tiling large bitmaps
Answer: B

70. An important parameter in designing a vector display’s deflection system is its bandwidth which affects
A) Pixel color depth
B) Speed and smoothness with which the beam can follow rapid direction changes
C) Memory addressing modes
D) Frame buffer size
Answer: B

71. Vector generators can implement circle drawing by computing successive endpoints using
A) Raster masks
B) Incremental trigonometric or differential algorithms (e.g., midpoint circle via segments)
C) Pixel lookup tables only
D) Texture mapping
Answer: B

72. Which of the following is true about coordinate precision in a display list?
A) It is irrelevant for line drawing
B) Higher precision reduces visible geometric quantization
C) Lower precision always improves quality
D) Precision only affects color, not geometry
Answer: B

73. When converting a filled polygon to vector commands for outline drawing, the system must also consider
A) Pixel clock frequency
B) Line join and cap styles to represent outlines correctly
C) Number of pixels horizontally only
D) DAC color depth exclusively
Answer: B

74. In analog deflection systems, thermal drift can cause
A) Faster frame rates
B) Gradual distortion or misplacement of vector positions
C) Increased color depth
D) More precise coordinates
Answer: B

75. Vector display hardware that supports clipping will usually implement clipping on
A) Per-pixel basis
B) Primarily on vector endpoints using line-clipping algorithms (Cohen-Sutherland, Liang-Barsky)
C) Color channels only
D) Phosphor slices
Answer: B

76. If you want to render dashed lines on a vector display, you would typically implement this by
A) Pixel masking in frame buffer
B) Breaking a vector into multiple short draw commands with blanking between them
C) Using a texture map
D) Increasing phosphor persistence
Answer: B

77. The visible smoothness of a traced curve in a vector display depends mainly on
A) Color depth only
B) Segment length used to approximate the curve and deflection smoothness
C) Horizontal resolution alone
D) Number of bits in DAC only
Answer: B

78. In a system that uses both vector and raster subsystems, the vector output is often used for
A) Displaying photos
B) Overlays for annotations, outlines, and UI elements
C) Compressing textures
D) Replacing the need for DACs entirely
Answer: B

79. A vector display’s perceived line thickness can be changed by
A) Changing frame buffer size
B) Increasing beam intensity and defocus (bloom) or drawing parallel offsets
C) Altering pixel clock only
D) Reducing number of vectors
Answer: B

80. Which hardware limitation most directly increases visible jitter in vector tracing?
A) Frame buffer size
B) Low update rate of deflection DACs or insufficient bandwidth
C) Too much phosphor persistence
D) Excessive color depth
Answer: B

81. The vector display’s scan conversion is best described as converting
A) Pixels to line segments
B) High-level primitives to continuous beam motion commands
C) Bitmaps to triangles
D) Textures to polygons
Answer: B

82. If the vector drawing engine computes N points per second and each curve requires M points, maximum curves per second ≈
A) NM
B) N / M
C) M / N
D) N + M
Answer: B

83. A common software task before sending data to the display list is to perform
A) Per-pixel gamma correction
B) Geometric transformations and clipping
C) DAC calibration only
D) Phosphor aging simulation
Answer: B

84. Which of the following improvements would most reduce flicker for a complex vector scene without changing persistence?
A) Reduce vector count
B) Increase refresh rate (redraw scene more frequently)
C) Lower DAC resolution
D) Use a smaller display list
Answer: B

85. The time required to redraw a frame in a random-scan system is roughly proportional to
A) Display resolution in pixels
B) Total vector length or number of vectors to be traced
C) Frame buffer size
D) Number of colors supported
Answer: B

86. Distortion due to magnetic interference in a vector CRT primarily affects
A) Color fidelity
B) Vector position and straightness
C) Pixel intensity only
D) DAC lookup tables
Answer: B

87. If a vector display’s display list supports hierarchical grouping (sub-lists), benefit is mainly
A) Reduced deflection nonlinearity
B) Easier transformations and reuse of compound objects
C) Increased frame buffer usage
D) Higher DAC bit depth
Answer: B

88. Which technique helps ensure consistent brightness for vectors of different lengths when the beam speed is fixed?
A) Vary deflection frequency only
B) Modulate beam current inversely with length or adjust dwell time per unit length
C) Change phosphor type per vector
D) Lower the display list size
Answer: B

89. When converting a Bezier curve for a vector display, the curve is subdivided until segments are short enough that
A) They match pixel boundaries exactly
B) Their straight-line approximation error is below a visual tolerance
C) They form a perfect circle
D) They require no DACs
Answer: B

90. The purpose of a “blanking” command in a vector display is to
A) Clear frame buffer rows
B) Turn off the beam between drawing segments to avoid drawing unwanted strokes
C) Increase phosphor intensity temporarily
D) Send data to CPU
Answer: B

91. For improved performance, a vector display may store frequently used objects in
A) Frame buffer as bitmaps only
B) A compiled or cached display list with transformed coordinates
C) ROMDAC exclusively
D) The phosphor layer
Answer: B

92. A limitation of analog deflection compared to digital sampling is that analog circuits are more prone to
A) Infinite precision
B) Drift, noise, and temperature sensitivity
C) Pixel overflow
D) Higher storage efficiency
Answer: B

93. In vector graphics hardware, “gouraud-like” shading of lines can be approximated by
A) Rasterizing polygons only
B) Gradually varying beam intensity along a vector
C) Modifying DAC resolution mid-trace
D) Changing deflection speed only
Answer: B

94. Real-time vector animation is most limited by
A) Pixel clock only
B) The throughput of the vector generator (vectors/sec) and deflection bandwidth
C) The number of colors supported
D) The presence of a frame buffer
Answer: B

95. The main difference between storing object geometry in display list vs storing as bitmap is that display lists are
A) Larger in memory always
B) More compact for geometric shapes and support easy transformations
C) Faster for texture rendering
D) Necessary for photographic images
Answer: B

96. When implementing dashed or dotted strokes, blanking intervals should be inserted where?
A) Inside the frame buffer rows
B) Between short draw segments according to dash pattern
C) Only at vector ends always
D) During vertical retrace exclusively
Answer: B

97. If a random-scan system traces vectors at a nominal beam speed and a complex scene takes too long to redraw, one acceptable approach is to
A) Increase phosphor decay rate only
B) Implement level-of-detail: draw coarse approximations at lower frequency and refine critical regions more often
C) Remove deflection coils
D) Lower DAC resolution to zero
Answer: B

98. In vector systems, a hardware feature that enables very accurate circular arcs without segmentation is
A) Frame buffer interpolation
B) Dedicated arc generator or hardware trigonometric approximator
C) Pixel shader acceleration
D) Texture lookups
Answer: B

99. The major maintenance issue for heavy-use vector CRTs is
A) Frame buffer wear
B) Phosphor burn-in and aging of deflection components
C) Pixel dead spots like in LCDs
D) Excessive texture corruption
Answer: B

100. The devices that most directly convert digital vector coordinates into analog voltages for the deflection coils are
A) Frame buffers
B) Digital-to-Analog Converters (DACs)
C) Phosphor drivers
D) RAMDAC only for pixels
Answer: B