Whether you're using a handheld, laptop or desktop device, the data and software reside in the system itself, or they live on a server somewhere else in the network cloud, but they're all in the same place.

But that constant may change. Thanks to flash memory, it may soon be practical to have all of your data, plus most of your software, sitting conveniently in your pocket. When that happens, consumer and business computing alike could change significantly.

Here's how the basic hardware setup could develop: Instead of relying on fixed disks, PCs would have ports for two to four or more flash drives. One or two would hold the operating system and most of the programs. The others would be focused mainly or entirely on data. And these flash drives would be portable from system to system, although there might be a partial exception for small devices such as cell phones, cameras, personal organizers or music players. But even if they kept a little onboard storage, it could be loaded from and backed up to a flash drive fitting into at least one port.

This concept has one huge difference from most other diskless PC plans: Rather than all living on a big server in the cloud, your personal data (and software) would never leave your custody. Thus, issues of network reliability, service provider lock-in, service-provider privacy safeguards and so on would all be mitigated. What's more, migration is almost a nonissue; older fixed-disk computers with USB ports fit into that diskless world perfectly well.

I love the hardware implications of this idea. First of all -- continuing the theme of last month's column ("Managing Data at RAM Speed," Nov. 14) -- every PC would benefit from huge improvements in memory-access speed. Beyond that, banishing the disk would slash laptop power requirements, and that means a huge overall weight reduction. And like other ideas about diskless PCs, this one would make it more affordable to optimize monitors, signal processors and the like for particular kinds of applications and room environments.