The NTSC 2600's pixel aspect ratio is x:y ≈ 5:3, i.e.
  1 scanline height ≈ 0.6 color clocks.

 The following trajectory scaling factors account for the pixel
 aspect ratio and a given trajectory angle:

                   .--------------------.----------------.
                   |      delta y       |     delta x    |
                   | (scanline heights) | (color clocks) |                  |
    .--------------+--------------------+----------------+
    | Vertical     |         1          |       -        |
    +--------------+--------------------+----------------+
    | Horizontal   |         -          |      0.6       |
    +--------------+--------------------+----------------+
    | 45° Diagonal |        1/√2        |     0.6/√2     |
    '--------------'--------------------'----------------'

 In order to make use of the collision registers we'd like
 to cap visible player movement in a single frame to one
 scanline height vertically and one color clock horizontally.

 We've chosen to have six evenly spaced sailboats speeds,
 ranging from 0 to a maximum of 1 unit distance.
 The following summaries precalculate the binary scalings of
 the x and y deltas corresponding to each speed and trajectory
 angle combination.

 N.B. Binary scaled $0100 = 1 unit distance = 1 scanline height.

 Vertical Trajectory Summary
 ---------------------------

                    .---------------------------------------.
                    |     delta y (in scanline heights)     |
  .-----------------+-------+-------+-------+-------+-------+
  |    speed rating |   1   |   2   |   3   |   4   |   5   |
  +-----------------+-------+-------+-------+-------+-------+
  | #unit distances |  1/5  |  2/5  |  3/5  |  4/5  |   1   |
  +=================+=======+=======+=======+=======+=======+
  |     x1 scaling  |  0.20 |  0.40 |  0.60 |  0.80 |   1   |
  +-----------------+-------+-------+-------+-------+-------+
  |  binary scaling |  51.2 | 102.4 | 153.6 | 204.8 |  256  |
  +-----------------+-------+-------+-------+-------+-------+
  |   subpixel byte |  $33  |  $66  |  $99  |  $cc  |  $00  |
  '-----------------'-------'-------'-------'-------'-------'


 Horizontal Trajectory Summary
 -----------------------------

                    .---------------------------------------.
                    |       delta x (in color clocks)       |
  .-----------------+-------+-------+-------+-------+-------+
  |    speed rating |   1   |   2   |   3   |   4   |   5   |
  +-----------------+-------+-------+-------+-------+-------+
  | #unit distances |  1/5  |  2/5  |  3/5  |  4/5  |   1   |
  +=================+=======+=======+=======+=======+=======+
  |    x0.6 scaling |  0.12 |  0.24 |  0.36 |  0.48 |  0.6  |
  +-----------------+-------+-------+-------+-------+-------+
  |  binary scaling |  30.7 |  61.4 |  92.1 | 122.8 | 153.6 |
  +-----------------+-------+-------+-------+-------+-------+
  |   subpixel byte |  $1e  |  $3d  |  $5c  |  $7a  |  $99  |
  '-----------------'-------'-------'-------'-------'-------'

 45° Diagonal Trajectory Summary
 -------------------------------

                    .---------------------------------------.
                    |        delta x (in color clocks)      |
  .-----------------+-------+-------+-------+-------+-------+
  |    speed rating |   1   |   2   |   3   |   4   |   5   |
  +-----------------+-------+-------+-------+-------+-------+
  | #unit distances |  1/5  |  2/5  |  3/5  |  4/5  |   1   |
  +=================+=======+=======+=======+=======+=======+
  | x0.6/√2 scaling | 0.084 | 0.169 | 0.254 | 0.339 | 0.424 |
  +-----------------+-------+-------+-------+-------+-------+
  |  binary scaling | 21.72 | 43.44 | 65.16 | 86.88 | 108.6 |
  +-----------------+-------+-------+-------+-------+-------+
  |   subpixel byte |  $15  |  $2b  |  $41  |  $56  |  $6c  |
  '-----------------'-------'-------'-------'-------'-------'

                    .---------------------------------------.
                    |     delta y (in scanline heights)     |
  .-----------------+-------+-------+-------+-------+-------+
  |    speed rating |   1   |   2   |   3   |   4   |   5   |
  +-----------------+-------+-------+-------+-------+-------+
  | #unit distances |  1/5  |  2/5  |  3/5  |  4/5  |   1   |
  +=================+=======+=======+=======+=======+=======+
  |   x1/√2 scaling | 0.141 | 0.282 | 0.424 | 0.565 | 0.707 |
  +-----------------+-------+-------+-------+-------+-------+
  |  binary scaling | 36.20 | 72.40 | 108.6 | 144.8 | 181.0 |
  +-----------------+-------+-------+-------+-------+-------+
  |   subpixel byte |  $24  |  $48  |  $6c  |  $90  |  $b5  |
  '-----------------'-------'-------'-------'-------'-------'