Like many mobile phones, a portion of the ZM's back panel slides off to reveal the handset-style compact, removable 680mAh rechargeable battery. You almost expect to find a SIM slot beneath it. You don't, but you do get a second battery in the box which you can keep charged and ready to swap in when the first one dies. I've said it before and I'll say it again: this is the one thing Apple should learn from its competition. There's nothing worse than finding your iPod's battery has gone dead while it's been sitting on the shelf and you're just about to go out. If only you could just flip in a new power pack... That said, my box was market 'limited edition', so don't expect Creative to offer a second battery for ever.
Creative quotes up to 12 hours for the ZM's playtime on a single charge. I got just eight hours running two-odd hours' worth of 128Kbps MP3 files over and over out of the test machine's pre-installed power pack. That's not bad, but since it's some way from the claimed duration, I ran the test again, this time with the unopened spare battery, in order to be sure it had been given the correct three-hour initial charge. Again, the ZM didn't make it to 12 hours.
There's only one other flaw with the ZM's battery: inserting it tears the 'warranty void if removed' sticker on the inside of the device. Let's hope no one notices if I have to take it back, ahem.
Hidden inside the ZM is its 1in 5GB hard drive - a Seagate unit, I believe. Creative claims it's not only bigger than the iPod Mini's 4GB Hitachi HDD but more reliable. Maybe it is, but it's certainly a slow unit. It takes around five seconds to start playing a new song when you've already got one running, unless you're simply skipping tracks forward or back, and even that doesn't feel as responsive as other players do.
Saving a playlist takes a similar irritating duration, as does getting the ZM ready to record after you've selected Record from the context-sensitive menu - and again when you've selected Stop. Ditto opening a playlist listing.
The ZM's hard drive can be used as a USB Mass Storage device, but you have to enable it to do so first - it's by no means plug and play. Worse, the player limits how much of its disk space can be used for general files - you can choose from 128MB, 256MB, 512MB and then in 512MB intervals up to 2GB. Pardon me, but isn't it my choice how much space I use for music and for other files? To be fair to Creative, this could well be a limit imposed by Microsoft's Windows Media 10 DRM technology - which the ZM supports - desperate as the Beast of Redmond is to prevent us from using USB Mass Storage devices to copy media files whether we've a right to do so or not. Assume from the word go that people are thieves, and they'll soon tell you what they think of you by choosing other companies' products.
UpdateCreative tells me leaving the Removable Disk option disabled allows the whole disk to data storage. Not that this 'feature' is any way obvious from the ZM itself or even the manual...
The ZM's data partition mounts perfectly on other operating systems than Windows - just make sure you select the Removable Disk option on the ZM first - but as yet there's no way of accessing the music partition.