VIC Screen Dimensions:
  +------------------------------------------------------------------------+
  |                                          Upper Border: $08             |
  |  O V E R S C A N - A R E A                                             |
  |    +--------------------------------------------------------------+    |
  |    |                        Upper Border:                         |    |
  |    |                             $33                              |    |
  |    |                                                              |    |
  |    |Left Border:                                     Right Border:|    |
  |    |    $18                                              $157     |    |
  |    |                                                              |    |
  |Left|                                                              |Rght|
  |Brdr|                                                              |Brdr|
  | :  |              D E F A U L T   T E X T - S C R E E N           | :  |
  |$1E0|                                                              |$1DF|
  |    |                        Lower Border:                         |    |
  |    |                             $FA                              |    |
  |    +--------------------------------------------------------------+    |
  |                                                                        |
  |                                          Lower Border: $12B            |
  +------------------------------------------------------------------------+

    The horizontal values are sprite coordinates, the vertical are
    rasterline counts (= Y sprite coordinates + 1).
    All values are inclusive, e.g. rasterlines $33 and $FA do belong to
    the default text screen.

    In the timing schemes the horizontal overscan borders are marked with
    '[' and ']', the text screen borders with '(' and ')'.