- movement per pixel will be faster horizontally than vertically. We can accept that, or if movement is meant to be the same in all directions then sprites may need to move faster vertically to ensure the movement is consistent. This then has an impact on gameplay because sprites will take less time to move over the screen and any time based goals may need to be adjusted to compensate and make the game goals consistent.
Using mode 1 is the route to a quicker port because there are less changes to the game code.
=====Screen dimensions=====