FROM their origins as personal digital assistants (PDA) to hot handhelds for the road warrior, smart phones have come a long way.

They pack more punch, taking on many tasks that require a full-fledged PC, without sacrificing their pocket sizes.

Besides Wi-Fi and multimedia players, new devices like the Nokia N82, HP iPAQ 612 Navigator and WMg Atom V even come with an integrated global positioning system.

While smart phones are expected to engage their audience for many years to come, they face competition from an up and coming category, ultra-mobile PC (UMPC), such as the Eee PC from Asus.

The latter is designed to be a cross between a smart phone and a normal laptop, making it more hybrid.

Some makers are even testing cellular telephony features on UMPCs, making the new hybrid device even more compelling.

How do the phones and UMPCs compare on features?

Research firm IDC defines a smart phone as a cellular handset with a high-level operating system - such as BlackBerry, Linux, Symbian, Palm or Windows Mobile - for advanced applications like word processing, multimedia recording or Internet access. These scaled-down operating platforms require applications to be lite.

UMPCs, on the other hand, run on full-blown operating systems like Windows Vista. They are capable of doing everything a laptop does, only slower due to processor speed limits. While full-sized laptops boast duo cores and processors with speeds of more than 2GHz, the processor speed in UMPCs averages at 900MHz.

Another key difference between the smart phone and UMPC is RAM. Smart phones typically have 128MB of RAM, while UMPCs have many times more of up to 2GB.

The screen resolution of smart phones is lower at 240 x 320 pixels, while UMPCs have 800 x 480 pixels or higher resolution on 7-inch screens.

Because of their smaller sizes, smart phones come with micro USB 2.0 ports for portable storage media. UMPCs, on the other hand, use the normal USB 2.0 ports found in laptops.

Size has limited these phones' appeal as mini-computers next to UMPCs in more ways than one.

Take storage. Smart phones use flash as it has a smaller footprint. While flash gives users a faster response time, it's common to find devices with a capacity of only 16GB. Meanwhile, the hard disks in UMPCs can store from 30GB to 160GB of data.

Touchscreen or keyboard input is another area.

Typing on a qwerty keyboard, whether physical or virtual, would definitely be easier on a larger device for users with bigger hands.

If cellular connectivity is the primary function, the smart phone is the clear choice.

IDC estimated that 700,000 units of smart phones shipped in Singapore last year compared with only 3,000 UMPCs. But the much lower shipment is due largely to the UMPC market being only two years-old.

"A lot of people also buy smart phones because of the phone feature," said Bryan Ma, director of personal systems research at IDC Asia-Pacific.

Their designs have matured significantly over the years, attracting even non-data users.

He does not expect the smart phone to replace the PC or be replaced as each device category serve markets with differing needs.

Of the 31 million smartphones shipped in Asia Pacific (excluding Japan) last year, 82 per cent run on the Symbian operating system. Linux was a distant No. 2 with 9 per cent market share, and Windows Mobile, 8 per cent.

The top handset maker was Nokia, with 80 per cent market share, followed by Motorola (9 per cent) and Dopod (2 per cent).

This story was first published in The Straits Times Digital Life on 15 April 2008.