Handspring has finally released the long awaited colour version of the popular Visor range; the Prism. The Visor has quickly become a popular PalmOS handheld, but if you wanted colour, the only option up to now was the Palm IIIc.

The cobalt blue Visor Prism (the only colour available) still retains the Springboard slot for much-needed expansion capability and the only physical differences, compared with its mono siblings, are a slight increase in thickness due to the battery pack and the power button, which is now found on the right-hand side.

Driven by a 33MHz Motorola Dragonball VZ processor supported by 8MB of RAM, and using the latest Palm OS (3.5.2H), the Visor Prism is not noticeably slowed by its colour screen. The 16-bit colour (65,535 colours) TFT screen is bright and easily viewed from most angles. A point to watch out for is that the Visor Prism, like all devices based on the Palm OS, has a screen resolution that's restricted to 160x160 pixels, which makes the adjustable backlight seem grainy, although this isn't as bad as other models.

Because of the power needs of the colour screen, the standard pair of AAA batteries used by the grey-scale Visors has been replaced by a rechargeable but non-removable Lithium Ion battery pack. The AC adapter plugs into a port, built into the USB connector on the desktop cradle. The battery pack provides about four hours of continuous use when fully charged. Usefully, the Visor Prism has a charging light built into the front casing; a green LCD shines when the unit is in the cradle, indicating the unit's charge status. It flashes until the unit reaches full charge, at which time it remains steady.

The Visor Prism includes all of the standard Handspring applications as well as some new, more powerful versions of earlier software. Date Book Plus enhances the existing Datebook application by adding floating appointments, integrated to-dos, and a journal. The scientific and business calculators are much-improved versions of the standard OS application and include Maths, Trig, Finance, Logic, Statistics, Weight/Tmp, Length, Area, and Volume functions. Other functions have been improved too - the world clock is great for frequent fliers, as you track the time in your home city while visiting abroad, and check out when the sun will rise and set, although this is something that's been available in other PDAs (e.g. Psion) for many years.

As power-packed as the original Visor but faster, with a good colour display, the Visor Prism is still the PDA with real expansion potential. The downside is that it is a little bulkier and heavier than the original Visor and also rather expensive.