The first portable computer based on Intel's Centrino Atom is due in June, although it will be bigger and more expensive than such devices were expected to be.

The Willcom D4 ultramobile PC is manufactured by Sharp and will be priced at ¥90,200 (£455) with a two-year data contract that costs an additional ¥1,600 (£8) per month.

Intel launched Centrino Atom at the Intel Developer Forum in Shanghai, but only showed prototypes of portable computers based on the new chips. However, Intel executives promised 20 such devices are in the works and will ship soon. The Willcom D4 announced Monday appears to be among those devices.

Centrino Atom was developed for small, pocketable devices based on Linux that Intel calls mobile Internet devices, or MIDs. These devices were expected to be priced starting from US$500 (£250), according to Intel.

Besides being substantially more expensive than the estimated price, the D4 is also bigger. At 84 millimeters by 192 millimeters by 26 millimeters and weighing in at 470 grams, the D4 is easily portable but not pocketable.

Unlike other prototypes that have been rolled out, the D4 is the first Centrino Atom device to be announced with a release date. The computer has a 1.33GHz Atom processor, a 5-inch widescreen display, 1GB of RAM, a 40GB hard disk, and includes support for Willcom's PHS (Personal Handyphone System) data network, as well as Wi-Fi and Bluetooth. It has a slide-out keyboard and a monitor that tilts up slightly, making it easier to read when typing on a flat surface.

The D4 runs Windows Vista Home Premium, instead of a mobile version of Linux. It also comes with Microsoft Office Personal 2007 with PowerPoint 2007.