PhatLinux is another distribution that touts its ability to be installed "on top" of Windows. It's been around since 1998, with a strong number of distribution sites and support options. The people at PhatLinux have also tried hard to make Linux into a "Windows clone," in hopes of luring more users over from the Windows side. On its Web page, it mentions that it "includes KDE, X-Windows, [and] Netscape."

An important thing to note is that like most "Linux-on-Windows" distributions, Linux does not actually run from within the Windows operating system. What the Linux loader usually does is reboot the machine into an MS-DOS mode, at which point the Linux kernel is loaded into memory via the LOADLIN DOS command, and booting begins. This is not an unusual maneuver among Linux distributions--indeed, this is one of the recommended ways for loading Slackware Linux--and the reason why this works well is that Linux needs full control of memory.

Indeed, Linux's stability lies in its ability to keep tabs on all system memory. This means being able to read and write areas of memory that Windows has declared "protected." By rebooting the machine into DOS mode, (almost) all Windows code has been removed from memory, allowing Linux to have full control over it.

However, those people trying to run PhatLinux (or any other Linux that runs "on top" of Windows, for that matter) on Windows NT 4.0 or Windows 2000 will be out of luck. Since neither OS has a true DOS mode (only a Command Prompt, running under a NT Virtual Machine), Linux isn't able to load on top of either of these OSes. For the purpose of this evaluation, we used a fresh Windows 98 machine with 32MB of RAM and two 1GB hard drives.

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