(1) An optical disc drive that supports more than one format. See Blu-ray.
(3) A hard drive with a disk cache made of flash memory. If the next set of data called for by the computer is in the cache, the transfer is much faster than reading from the disk. The capacity of the flash cache is a small percentage of the drive's total space. RAM Caches: DRAM and SRAM Since the 1990s, hard drives have had a small dynamic RAM (DRAM) cache built in or on the controller. Because DRAM is faster than flash memory, hybrid drives generally use both DRAM and flash memory caches, and they may use static RAM (SRAM) instead of DRAM because SRAM is even faster. See cache, flash memory, solid state drive, dynamic RAM, static RAM, Robson cache and NV cache.