Quantum Corporation is a manufacturer of data storage devices and systems, including tape drive and disk-based systems. The company's headquarters is in San Jose, California. From its founding in 1980 until 2001, it was also a major disk storage manufacturer (usually second-place in market share behind Seagate), and was based in Milpitas, California. Quantum sold its hard disk drive business to Maxtor in 2001 and now focuses on integrated storage systems.