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How Dreamcast Works

Dreamcast Console

Lets take a look at the components inside a Dreamcast, and what their capabilities are:

Processor: 64-bit Hitachi SH-4

Processor: 64-bit Hitachi SH-4

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  • Processor clock speed: 200 MHz
  • MIPS (Million Instructions Per Second): 360
  • Bus speed: 800 MB per second
  • Cache: Instruction: 8 K; Data: 16 K

Graphics: 128-bit 100 MHz NEC PowerVR 2DC

  • Resolution: 640x480 or 320x240 interlaced
  • Colors: 24-bit (16,777,216) maximum, as well as 16-bit (65,536) mode
  • Polygon rendering: 3,000,000 polygons per second
  • Memory: 8 MB video RAM

Geometry engine:

  • Alpha blending
  • Perspective correction
  • Gouraud shading
  • Anistropic, bilinear and trilinear mip mapping
  • Z-buffer

Audio: 45 MHz Yamaha Super Intelligent sound processor

  • Channels: 64
  • Sample rate: 44.1 KHz
  • Special effects: reverb, delay and surround sound
  • Memory: 2 MB RAM

Memory: 16 MB

Operating system: Windows CE-based or custom Sega OS

Game medium: Proprietary GD-ROM (Gigabyte Disc)

  • Transfer speed: 1800 kilobytes per second
  • Storage capacity: 1.2 gigabytes
  • Memory buffer: 128 K

Modem: 56 kilobits per second (Kbps)

The Dreamcast is the first console that has a built-in 56 Kbps modem. It was added to enable online play over a phone line, allowing users to play games against each other across long distances. In addition to the built-in modem, Sega is working on a cable or DSL external modem. Broadband networks are being developed that will take advantage of such a modem and enable fast online games for the Dreamcast.

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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