PD disc - Computer Definition
(Phase change Dual disc) An earlier rewritable optical disc from Panasonic that used phase change technology. Introduced in 1995, its 5.25" cartridges held 650MB and withstood 500,000 rewrites. The PD drive also read CD-ROMs, but not Panasonic's prior phase change (PCR) disks. See phase change disc and optical disc.