Buzz
The SETI@Home screensaver is a well-known program that actually contributes to a meaningful cause.For most users, a screensaver appears when you leave your computer idle for a few minutes. It could be a simple black screen, a program like SETI@Home, or something quirky like dancing macaroni.
So, what exactly is a screensaver? What is its purpose? And how does it know when to activate? In this article, we'll dive into what happens behind the scenes and explore its mechanics.
What is a Screensaver?
A screensaver is essentially an executable file that has been renamed from .exe to .scr. File extensions indicate the type of file the computer is dealing with. For instance, winword.exe refers to a word-processing application, while article.doc is a text file that can be opened in Microsoft Word.
An executable file is one that the computer's operating system recognizes as a program or application. Files with .exe (or .scr) extensions are designed to run on their own, without needing another file, or if another file is required, they indicate which one is necessary.
Thus, we understand that a screensaver is, at its core, a program. When a screensaver file is placed in the Windows or System directory with a .scr extension, Windows identifies it as a screensaver and adds it as an option in the Display properties window. This file can be programmed in various ways, including:
- Simply showing a black screen
- Utilizing vector graphics to create designs
- Loading and displaying specific images or a group of images
- Showing a particular line of text
- Presenting an animation or series of animations
- Playing a video clip
- Including music or sound effects
- Displaying information from another program or website
- Allowing interaction with another program or website (For example, the Mytour screensaver keeps the mouse active, letting you click different icons to visit specific sections of the Mytour site.)
- Requiring a password to deactivate and return to the desktop
Most screensavers incorporate a combination of these features. Except for slideshow screensavers that show a series of images, most screensavers typically move images, text, or animations across the screen. Screensavers with custom interfaces that don't rely on the Display properties window are rarer and usually don't use the .scr extension. These types often require installation through a setup program to configure them correctly.
What Purpose Do Screensavers Serve?
Screensavers were initially created to safeguard computer monitors from phosphor burn-in. In the early days of CRT monitors, especially monochrome ones, the same image displayed for extended periods would cause the phosphors that made up the pixels to burn at a constant rate. This long exposure would leave a permanent discoloration on the CRT’s glass surface, resulting in a faint ghost image overlaid on the screen. With advances in display technology and the introduction of energy-efficient monitors, screensavers have become less essential, though we still continue to use them.
Here are the primary reasons we still use them:
Step-by-Step Process
Let's walk through how a screensaver operates on a Windows 95/98 system. Although the specific commands and details may vary, the basic process is the same across different computer systems.
Your computer constantly tracks the activities taking place between its components. When it detects that the keyboard and mouse have been inactive for the time specified in the screensaver settings under the Display properties window, it sends a command to the foreground application to see if it can activate the screensaver. If the foreground application is running a Computer Based Training (CBT) window or a non-Windows program like one from the MS-DOS prompt, Windows won't start the screensaver.
Here’s the exact process that happens:
- To determine if it can start the screensaver, Windows sends a command to the foreground application. This message essentially asks, "Can I start the screensaver?" Non-Windows programs won’t understand this request and will not respond, while a CBT application will acknowledge it but respond with, "No, I’m in training mode right now." Other applications should accept the request and allow the screensaver to start.
- Next, Windows checks the SCRNSAVE.EXE=____ line in the system.ini file to see if a screensaver has been designated. If the entry is empty, the screensaver is not executed. But if a file is listed, it attempts to load that file. If it’s a valid screensaver, it launches and overlays the current desktop with the screensaver visuals.
- The screensaver keeps running until Windows detects any input from the mouse or keyboard. With most screensavers, any mouse movement or key press will stop it instantly. However, screensavers can be programmed to only stop if certain keys or buttons are pressed, or if the mouse is moved a specific distance. This is particularly helpful in interactive screensavers.
- If Windows detects input and needs to terminate the screensaver, it checks whether password protection is enabled. If so, a prompt will appear asking for a username and password. Without password protection, the screensaver simply ends. If password protection is enabled, entering the wrong credentials will keep the screensaver running. While this provides security, it’s crucial to note that screensavers in Windows 95/98 create their own password dialog boxes and request the password directly from the system. If you're unsure about the source of the screensaver, be cautious when using password protection, as hackers may exploit this weakness to capture passwords. This isn’t an issue with Windows NT, where screensavers can only invoke the system password dialog box, not their own.
In the next section, you'll learn how to set up your own screensaver.
Creating Your Own Screensaver
Configuring a screensaver in Windows 95/98 is a straightforward task. Here's how you can do it:
- First, click on Start, followed by Settings, and navigate to the Control Panel.
- Once the Control Panel window appears, double-click the Display icon to open the Display Properties window.
- Next, go to the Screensaver tab and select your preferred screensaver from the drop-down menu.
- Set the duration of inactivity before the screensaver kicks in by entering the time in the provided box.
- If you wish to preview the screensaver, click Preview. If you need to adjust any settings, click Settings. This will open a window with customizable options, depending on the screensaver you choose.
- Once satisfied with the settings, click OK. To secure your screensaver with a password, check the 'Password protected' box. Click OK again to finalize your screensaver setup.
There are multiple methods to obtain a screensaver:
- Choose from the pre-installed screensavers that come with Windows
- Purchase a collection of screensavers
- Find and download one of the many free screensavers available online
- Create your own screensaver using a program designed for that purpose
- Write your own screensaver from scratch by coding it yourself
Years ago, commercial screensaver collections were quite popular. However, with the rise of the internet, free screensavers have become so abundant that few people are willing to pay for them. Programs like Screen Saver Builder allow you to create personalized screensavers by combining images, animations, and sounds. If you're a developer, there are plenty of online resources that provide both technical details and even source code to help you write your own screensavers. Once you have created that amazing screensaver, several websites allow you to share it with others by uploading it to their platform!
