head disk assembly - a sealed, high capacity mainframe hard disk with integral heads, as opposed to a removable disk
HDA - head disk assembly. The mechanical components of a disk drive (minus the electronics), which includes the actuators, access arms, read/write heads and platters.
... Data storage assembly (head/Disk/Assembly) for hard disk drives, with a data transfer rate per second of 3,9 or 4,2 megabytes, comprising read/write heads and 9 or 11 magnetic discs ... the whole incorporated in a single hermetically sealed housing ...
