Hybrid hard disks incorporate a nonvolatile cache in a traditional mechanical design. The photo here shows the mechanical part and the cache part separated out.
The cache (also called flash memory) ranges from 128MB to 1GB or more. It's used by the SuperFetch feature of Windows Vista to store frequently accessed data, providing faster access speed. It also provides lower power consumption, as the mechanical part of the hard drive remains at rest, while Windows Vista accesses only the cache area of the drive.
The majority of hybrid hard drives will come in a 2.5-inch form factor with an ATA interface and capacity of up to 100GB. The first vendor to showcase a .
Also at WinHEC, Samsung introduced its first solid-state hard drives. In these devices, the entire hard drive is nonvolatile cache without any moving parts. (It's almost like using a USB thumbdrive as the main hard drive for the notebook.) The device aims to significantly reduce the boot time of a PC, as well as improve performance. However, the price per gigabyte of a solid-state hard drive is currently about 30 times higher than that of a traditional hard drive, and capacity is limited to about 30GB.