Seagate Technology PLC (commonly referred to as Seagate) is an American-founded data storage company that was incorporated in 1978 as Shugart Technology. Since 2010, the company is incorporated in Dublin, Ireland, with operational headquarters in Cupertino, California, United States. Seagate developed the first 5.25-inch hard disk drive (HDD) in 1980, the 5-megabyte ST-506. They were a major supplier in the microcomputer market during the 1980 ‘s, especially after the introduction of the IBM XT in 1983. Today Seagate along with Western Digital dominates the HDD market.