USB - HDD After hard drive simulation model, DOS startup display C: disk, HP made U disk formatting tool U disk or use the boot mode. This pattern compatibility is very high, but for some only support USB - ZIP model computer cannot be started. USB HDD + Enhanced USB HDD model, after the DOS boot display C: disk, compatibility is higher than the USB HDD model. But the only support USB - ZIP computer cannot be started. USB - ZIP Big floppy disk mode) : after start U disk drive is A; USB - ZIP high-capacity floppy simulation model, the model in some older computers is only optional mode, but for most of the new computer compatibility is not good, especially the large capacity U disk for more than 2 gb. FlashBoot make USB - ZIP start U disk using this pattern. USB - the USB - ZIP ZIP + enhancement pattern, shows A: after the DOS boot disk, some display C: disk (according to the computer's BIOS support is different), support USB - ZIP/USB - HDD dual mode, so as to achieve high compatibility. The downside is that some will support USB - HDD computer USB this pattern is thought to be the USB - ZIP to start, leading to large capacity U disk compatibility.