Double-Edged Sword?

The current crop of NC1s rely on older networking protocols, such as the X Window System and remote sessions to Windows NT, for most of their functionality. Most of the NC1s we tested had Java compilers, where everything runs through a totally interpreted Java virtual machine (VM). Yet the vendors of these NC1s tout as their systems' biggest benefit today the ability to run ICA protocols and multiuser Windows applications. Some NC1 vendors even say that Java would be best served running on a full-fledged PC.

Arguably, Java is far from perfect. But do its disadvantages outweigh its pluses? One of the primary responsibilities of the Java V M is to interpret incoming code into the native machine language. This allo ws the same Java applet to be shared by different hardware without being recompiled for each platform.

This approach presents the usual performance problems. For example, the first time you import an object into the Java VM, it gets interpreted. As a result, it's slow. However, future calls made to that object are much faster, since it's then in memory.

In addition, the Java VM was designed without a permanent file system. For temporary storage it uses cache, which gets cleared out when it's not regularly used. Applications in the Java VM are restricted from making I/O calls. On the upside, this might provide some security advantages because it allows you to run applications in a protected environment. It's also useful if you download virus-prone programs from the Internet. The disadvantage is that it requires you to reload all applications into the Java VM each time you boot up. Although Java cross-platform compatibility now comes at the expense of performance, just-in-time (JIT) compilers and Java chips are expected to make serious inroads within the next year and could narrow the gap.