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Shipped in September 1956, the first 5MB hard disk unit weighed over a ton (2,000 pounds) and was used by the IBM 305 RAMAC, which was the first commercial computer to have a moving-head hard disk. The drive occupied 16 square feet and used fifty 24-inch platters read by two independently moving arms that had an average access time of 600ms.
Also referred to as the IBM 350 disk storage unit, the drive was about the size of two refrigerators and was mounted on a metal frame that was anchored to the floor. It required a dedicated air conditioning system to keep the temperature and humidity at the proper levels to protect the delicate magnetic disks. Due to its size and weight, it was typically only used in large data centers and mainframe computer rooms.
At the time, 5MB of storage provided the ability to keep five million characters of accounting data (64,000 punch cards or the equivalent of about 2.5 million pages of typed text) and unlike tape storage which needed to be read from start to finish to find data, the RAMAC's drive could access the same information randomly. It was a significant improvement over earlier forms of data storage and paved the way for the development of larger and more reliable hard drives in the years to come.
Production ended in 1961 as the RAMAC computer became obsolete the following year upon the arrival of IBM's 1405 Disk Storage Unit for the IBM 1401. By 1981, Apple introduced its first hard drive known as the "ProFile" which first offered 5MB of storage for $3,499 and was small enough to sit on top of the Apple II, III and Lisa computers.