0077 is used by the game engine to force scrolling in a horizontal scrolling stage (1, 5, 6, 7, 8). This is used when the game needs to make a background object look like a sprite, like the big spiked tanks in the Snow Field. However, if you force a value into it, the game will auto scroll through the whole level at the speed of the value you enter. 01 is slow, 0F is fast. Giving yourself infinite lives and the spray gun makes it possible to beat most of these areas.