Although the unit is supplied with the latest Microsoft Pocket PC software, Casio uses non-reprogrammable memory for this, so the prospects for upgrading the operating system are not as good as for PDAs that use CompactFlash for this software. Under continuous usage, the lithium ion battery lasted just over five hours and took about the same time to fully recharge while in use. It is one of the very best PDA screens available and is usable outdoors, although direct sunlight causes problems as with any similar device. Under more normal lighting conditions the video player and sample files provided gave excellent rendition for a unit of this size and showed the display to its best. Sound quality was better than one would expect from such small speakers.
Synchronisation is fast and user-friendly thanks to the USB cradle.
Power can be plugged into this or directly into the unit. For those who prefer to synchronise their applications via a serial interface, an optional RS-232 cable costs about 25, and there is also an optional cable to connect the device to a mobile phone. The ActiveSync 3.1 software allows easy interfacing with a desktop PC for synchronisation, backup and basic file copying. IT Week Labs' processor test revealed that rival systems such as the Compaq iPaq H3650 that are built using Intel's 206MHz StrongArm processor are noticeably faster. In practice, although the E-125's processor is adequate for most tasks, when the system got overloaded the speed of updates to the screen slowed to a crawl and response times were measurable in tens of seconds.