Friday, October 02, 2009

The Wall Wart Is A Computer

It’s been half a century since computers were behemoths that filled entire buildings and sucked as much power as a good size town. Now they sit in a rack or on your desk top and suck as much power as a good size TV. Laptop computers and notebooks are less power hungry and have AC supplies with prongs attached to plug right into a wall outlet. The power supply or transformer in a palm-size plug is so common that it has its own designation: wall wart. But what if instead of the wall wart powering the computer, the wall wart was the computer?

Amazing, but true. Computers have shrunk to the size that they fit right into the size of a container that used to be just for the power supply. Oh, we’re done marveling at the pocket calculator, the digital watch, or the light switch timer and dimmer. Arguably, these devices all have small computers inside. But they’re special purpose circuits. You won’t be downloading software to your digital watch any time soon. You will be doing just that with what’s called a “plug computer.”

The plug computer is a general purpose computer, like a PC, housed in a small plastic case with two power prongs that plug into a standard wall socket. The Marvell ShevaPlug is a good example. It boasts a 1.2 GHz CPU with 512 MB of flash memory and 512 MB of DDR2 SDRAM memory. I/O is a Gigabit Ethernet jack and a USB connector. The operating system? Why, open-source Linux of course.

By the way, the ShevaPlug draws about 2 watts. When your PC is completely off it probably draws more than that unless you pull the plug. Lots of peripherals, especially printers, are power vampires. They draw as much as 20 or 30 watts just to sit there on standby doing absolutely nothing but waiting around. The plug computer draws power too, but it just sips even when fully active.

So what’s a computer in a wall wart good for? With USB and Ethernet connectivity, it makes a really nice server. Plug in a hard drive and you’ve got network attached storage. Plug in a printer and you have a network print server. Plug in a video camera and you’ve got a webcam. How about serving up video content to an HDTV set over a network connection? Why not just use one as a low end desktop computer?

The era of the plug computer is just starting. Your home and office may be full of these some day. Right now they’re available in development kits for $99, but you’ll have to create your own applications software. Next year or the year after? You may well be able to go to an apps store and download all sorts of useful functions, similar to what’s happened with the iPhone.

I can hardly wait for the plug supercomputer. That would be a dozen wall wart servers plugged into one long power strip. Don’t laugh too loud. It might not be pretty, but it would be green - very green.

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