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How Dreamcast Works

Dreamcast Games

The Dreamcast has a drive similar to other CD-ROM drives, but the optical disc is proprietary.
The Dreamcast has a drive similar to other CD-ROM drives, but the optical disc is proprietary.

While Dreamcast games are similar to CD-ROM, the actual optical disc used is proprietary, and can hold up to 1.2 gigabytes of information. This is a lot of space -- most games use only a fraction of it for the actual game. What can eat up the space are the incredible full motion video intros and intermissions included in most Dreamcast games.

There is a noticeable delay while the game is loaded from the CD, which you do not get with cartridge-based games. Of course, the trade-off for faster loading is a significantly smaller amount of storage on a cartridge. Most Dreamcast games use a customized version of Microsoft Windows CE as their operating system; but some use Sega's proprietary Dreamcast operating system.

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Dreamcast CDs are just as susceptible to scratches and intense heat as normal CDs. Even more so in fact, since a scratch on a game CD can make it totally unusable.

The games available for the Dreamcast cover all the categories, and its library of games is increasing rapidly. Game prices range from under $20 for certain preplayed titles to over $75 for some of the hottest new games.

JavaScript is what is called a Client-side Scripting Language. That means that it is a computer programming language that runs inside an Internet browser (a browser is also known as a Web client because it connects to a Web server to download pages).

The way JavaScript works is interesting. Inside a normal Web page you place some JavaScript code (See How Web Pages Work for details on Web pages). When the browser loads the page, the browser has a built-in interpreter that reads the JavaScript code it finds in the page and runs it.

Web page designers use JavaScript in many different ways. One of the most common is to do field validation in a form. Many Web sites gather information from users in online forms, and JavaScript can help validate entries. For example, the programmer might validate that a person's age entered into a form falls between 1 and 120.

Another way that web page designers use JavaScript is to create calculators. Here are several examples:

To give you an example of an extremely simple JavaScript calculator, the HTML below shows you how to create a Fahrenheit to Celsius converter using JavaScript:

    
    
Fahrenheit to Celsius Converter Enter a temperature in degrees F:
Click this button to calculate the temperature
in degrees C:
Temperature in degrees C is:

If you have read How Web Pages Work and How CGI Scripts Work, then a good portion of this HTML will be familiar. This is the basic structure of any web page:

<html>
<head>
</head>
<body>
</body>
</html>

There is one piece of JavaScript code in the header that is the function to calculate the conversion from Fahrenheit to Celsius:

<head>
<script>
<!-- hide this script from old browsers
function temp(form)
{
  var f = parseFloat(form.DegF.value, 10);
  var c = 0;
  c = (f - 32.0) * 5.0 / 9.0;
  form.DegC.value = c;
}
<!-- done hiding from old browsers -->
</script>
</head>

The function is called temp. It contains JavaScript code to calculate a Celsius temperature.

In the body of the page there is a typical form:

<FORM>
<h2>Fahrenheit to Celsius Converter</h2>
Enter a temperature in degrees F: 
<INPUT NAME="DegF" VALUE="0" MAXLENGTH="15" SIZE=15>
<p>
Click this button to calculate the temperature 
in degrees C:
<INPUT NAME="calc" VALUE="Calculate" TYPE=BUTTON 
onClick=temp(this.form)>
<p>
Temperature in degrees C is: 
<INPUT NAME="DegC" READONLY SIZE=15>
</FORM>

This line is key:

<INPUT NAME="calc" VALUE="Calculate" TYPE=BUTTON 
onClick=temp(this.form)>

This is a normal button control. When the user clicks it, it calls the function in the head of the page because of the onClick notation.

As programming languages go, JavaScript is average difficulty. It is not especially hard to learn how to use it if you already understand programming, but if you are new to programming it is certainly not an easy language to start with. What you can do, however, is modify this sample code and expand it to create other calculators.


Here are several interesting links:

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