Array
Multiple disk drives configured to behave as a single, independent disk drive. See also Disk Array.
Array adapter
A bus-based (usually PCI) hardware device — such as an add-in card, group of motherboard ASICs, or a combination of both — that converts the timing and protocol of a host’s memory bus and an I/O bus. Usually used in entry-level servers, an array adapter also includes an on-board RAID co-processor to offload most of the RAID operations — for example, secondary RAID 1 writes and RAID 5 parity calculations — from the host CPU. This is in contrast to the microprocessor-based array controllers used in midrange and high-end servers, which also offload I/O commands. Array adapters improve performance over software RAID solutions embedded within network operating systems such as NetWare and Windows NT. These adapters provide the same connectivity functions as a standard host adapter.
ATA
Short for AT Attachment. A hard drive with an integrated controller. There are multiple levels of ATA standards including the base-level 16-bit IDE, ATA-2 (Enhanced IDE), Ultra ATA (ATA33), ATA66 and ATA100. A good explanation and tutorial is available at PC Guide.
ATAPI
ATA Packet Interface. Defines a set of commands supported through the ATA-2 interface for peripherals other than hard drives, such as CD-ROM, DVD-ROM, and tape drives.