As earlier reported by ZDNet UK, Palm has begun accepting preorders for an operating system upgrade for its older handheld computers. The upgrade is set to ship on 15 November, but those who order now will get a $10 (£7) discount, according to Palm. The preorder page is available on Palm's Web site. The OS upgrade, which adds the functions of Palm OS 4 and the Mobile Internet Kit to older Palms, will cost $39.95 on launch but is now available for $29.95. Palm was not immediately available for comment. The company advertised the upgrade earlier this week with an email to registered users. New Palm devices currently run the 4.0 operating system, but older devices are only able to upgrade to OS 3.5. Only PDAs with flash memory will be able to accept the upgrade. Compatible devices include the Palm Vx LE, Palm Vx, Palm V and Palm IIIc, according to Palm. The m100, IIIe and VII wireless series are among those that cannot be upgraded. Newer models, like the m505 and m125, are not eligible for the upgrade. The software will be a significant improvement for those running a 3.x or older operating system: it will add security features, improve management of alarms, add support for 64-bit colour and improve data entry. The upgrade includes Palm's mobile connectivity software, which adds wireless Internet and email access as well as mobile phone messaging. The previous upgrade is 3.5. Palm OS 4.0 was launched in September with the m125 handheld. Version 4.1 made its debut with the Sony N760C, but 4.1 is not significantly different from 4.0. Palm's upgrade only applies to Palm devices. Sony has already released an OS 4.1 upgrade and other Palm OS-based PDA manufacturers must come up with their own software update. See the Mobile Technology News Section for full coverage. See the Software News Section for full coverage. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Telecoms forum. Let the editors know what you think in the Mailroom. And read other letters.