http://en.wikipedia.org/wiki/IBM_305_RAMAC
IBM 305 RAMAC在1956年9月13日发布,是第一台使用可移动磁头的商用硬盘做挂载存储器使用。
The IBM 305 RAMAC, publicly announced on September 13, 1956[1][2], was the first commercial computer that used a moving head hard disk drive (magnetic disk storage) for secondary storage.