Armour health meter and smooth scrolling

There was no health meter in the original game and quite often your plane would seem to randomly explode for no plausible reason. Usually the reason why this happened is because in the original game there is actually a hidden damage counter. Every time the plane collides with flak, it is incremented. When it reaches a critical level your plane will explode. To resolve the confusion, I decided to add a kind of health meter to the flight instrument panel, which will give a visual representation of this level.

Smooth scrolling

I have also amended the functions that print hardware sprites on the screen so they could take a pixel coordinate rather than a character based coordinate and convert it to pixels. This enabled me to change the routine that scrolls the carrier onto the screen. Rather than using the existing time delay function, I just scroll the ship two hardware pixels at a time to simulate mode 1 sprites and wait for the next scan line. This makes the ship entrance a lot smoother. I also intend to work on the plane scrolling so it moves by pixels as well although I will need to still restrict movement to the grid for collision detection purposes.