As you are noticing, arcade games were all unique beasts.
(Almost) every one was unique. Among the differences were the size and orientation of the screen. The orientations can generally be classified as 'horizontal' and 'vertical'. Obviously, games with vertically oriented monitors are more suitable for PSPC/PocketPC devices with their taller-than-wide aspect ratio (and the reverse is true of desktop monitors).
Resolution is a bit more complicated. The original arcade games each had a fixed resolution (i.e. Galaga's display is 224x288, 720 is 512x384). Desktop monitors are usually able to display a wide variety of different resolutions, espically with some of the tricky programming techniques the MAME guys know :). So by carefully selecting an appropriate resolution, combined with possibly doubling the pixels of the original, MAME is in most cases able to make most any game fit pretty well on your desktop monitor.

With PSPC/PocketPC's the story is rather different. Our devices don't have monitors which can make a display of different resolutions; we are stuck with a LCD of a fixed resolution (240 wide x 320 high). It is just coincedence
that many 'classic' arcade games, espically those with vertical monitors, has resolutions which fit very nicely in this display (SI, Pacman, DK etc etc). However, those with horizontal monitors often don't quite fit (i.e. GnG is 256 wide; 16 pixels more than available). There are quite a few options as to what to do about that, the simplest of which is currently implemented: you don't see the right-most 16 pixel-columns of the game. Other options include splitting the difference (dropping 8 from each side), and 'squeezing' the image (i.e. dropping 16 pixel-columns evenly spaced from within the image). I'm working on implementing the split-the-difference method in MAMECE-10X. The 'squeeze' method would slow down the screen-drawing routine; and I can't come up with a nice reliable elagant algorithm to make it happen for all cases (remeber, we've only considered one case here, many many more exist).
Another possible solution for the horizontal-monitor games
which are slightly-too-wide is to rotate the display 90deg so it fits. This usually works fine for the display, however it often leaves the controls very difficult to use when the device is held that way :( not to mention that the display has a columnator [sp?] so it's more difficult to look at in any orientation other than 'normal'. I've only used this method for Track & Field because it only requires buttons for input. Most games require joypad & at least one button, which is difficult to do when they are on the same side of the device when held sideways. (things may be different for the iPaq, whose owners are used to having to play games using the press-the-joypad method for shooting).

Another 'special case' arises for game whose resolution it roughly twice that of our devices. In these games, a potential solution is to simply show every-other pixel in every-other line of the display. This is relatively simple and fast to do (versus other more general stretching/squeezing an image). This is what I've done to allow me to enable (and see the screen of :) the MCR games; including Tron. See my webpage at http://www.geocities.com/dgfinck to see how it looks :) Obviously, you lose some of the detail when you're only displaying 1 of every 4 pixels from the original, but it's still very usable.

To finish answering your question: forget 720, and in King Fu Master you should only be missing the right-most 16 columns, just as in GnG, so it shouldn't be a big deal.

Darren

> I have the Casio E-125. Has anyone had any screen resolution issues? Ive had
> problems with 720 and Tron, and Kung Fu master so far.The screen goes off into
> never never land. Much too big for the screen. Is there a fix?
>