Computers manipulate digital information, CRTs manipulate analog information. This means that somewhere, somehow the digital information that your computer works with needs to be converted into an analog signal that your monitor can work with. On PCs, video cards perform this digital to analog conversion using a Digital-to-Analog Converter (or DAC for short).

It's essential to understand that arcade games manipulate digital information, and that CRTs manipulate analog information. If you do not, you may find yourself getting confused when arcade game developers start talking in terms of pixels, resolutions, and frame rates, and when CRT manufacturers start talking in terms of bandwidth, timings, and refresh rates. Many people get lost when going from the analog world to the digital world and vise versa. But don't fret, it's not all that complicated. You just have to keep in mind that they are two different worlds.

In the digital world, everything from the analog world is systematically broken down into very small components. Essentially, an infinite data set (analog) is broken down into something finite (digital). An old color photograph, for example, has an infinite number of colors. It also displays an infinite number of shades of black and white. Film, like CRTs, manipulate and display analog information. This means that in order to edit an old color photograph on your computer, it needs to be broken down into something finite, something your computer can understand. In the digital world images are broken down into pixels. They take analog information such as an old color photograph and translate (i.e. scan) it into a set of pixels. The more pixels you use to translate an image into the digital world, the closer it comes to an exact duplicate of the analog original. If you used an infinite number of pixels to translate an image, then it would be an exact duplicate, but, of course, computers can't work with infinite numbers, so this isn't very useful. It just means that more is generally better (as far as replication accuracy is concerned).

In the analog world, everything from the digital world is turned from a discrete number of components into a continuous data set, or infinite number of components. For example, in order to view a scanned photograph on your computer monitor, your video card needs to convert the image's pixels (digital) into a signal of volts per second (analog). Naturally, this is done via your video card's Digital-to-Analog Converter.

So basically if you take an old photograph and display it on your CRT monitor, it has to go from analog (film) to digital (pixels) and then back to analog (CRT). Don't stress out if your a little confused about all this, just understand there are two different worlds out there, the digital one (computers) and the analog one (CRTs). If you understand that, then you're golden. I mention all this because many modeline newbies get confused when the digital and analog worlds collide. You just have to remember that there are two different worlds out there, the digital one and the analog one.

If you want to understand how images are mainipulated in the digital world, then you need to understand pixels, what they are, and how computers manipulate them to display images.