IBM is working hand-in-hand with Japanese watchmaker Citizen on new prototypes of IBM's WatchPad wearable computer, the companies announced last week.

The WatchPad 1.5, a wristwatch-sized device measuring 65x46x16mm and weighing 43g, runs Linux on a 32bit ARM processor at 74MHz. It has 8MB of DRAM and 16MB of flash memory as well as a speaker and a microphone.

It has a reflective monochrome LCD (liquid crystal display) QVGA screen, a fingerprint recognition device for security, and an acceleration sensor which detects the wearer's hand movements. It also has IrDA infrared capability, RS232C and Bluetooth network interfaces.

The wristwatch computer works not only as a PDA (personal digital assistant) but as a controller for PCs, using Bluetooth. Version 1.1 of Bluetooth, the version used for the prototype, can also be used for voice control, according to the companies.

IBM unveiled its first generation WatchPad 1.0 prototype in August last year, and has since exhibited it at a number of trade shows.

While that device was too premature for commercial use, according to Yoichi Takao, director of IBM's research laboratory in Tokyo, "this one is technically ready" as a result of co-developing the device with Citizen.

Reducing power consumption was key, according to Citizen. The battery now lasts for at least a day, while the processor speed is five times faster, the company said.

Citizen is developing the hardware for the WatchPad while IBM works on the software, so the companies view development of the device from different perspectives. Citizen hopes to expand the abilities of what a wristwatch can do as a small PC, rather than adding a telecommunication function.

IBM, on the other hand, expects the device will be used for browsing the internet and sending email, said Takao. He added: "Foma [NTT DoCoMo's third generation mobile phone service] can download moving images, then why not for WatchPad? A telephone handset is inconvenient for users to view moving images but, on a wristwatch, it is easier."

At the moment, though, IBM and Citizen need to make the battery life last more than a day and, considering the Foma phones have a tragically short battery life and are more than twice the size of the Watchpad, this goal looks some time away.