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A drum memory or drum storage unit contained a large metal cylinder, coated on the outside surface with a ferromagnetic recording material. It could be considered the precursor to the hard disk drive (HDD), but in the form of a drum (cylinder) rather than a flat disk.
The IBM 2301 is a magnetic drum storage device introduced in the late 1960s to "provide large capacity, direct access storage for IBM System/360 Models 65, 67, 75, or 85." The vertically mounted drum rotates at around 3,500 revolutions per minute, and has a head-per-track access mechanism and a capacity of 4 MB.
The IBM 305 RAMAC was the first commercial computer that used a moving-head hard disk drive (magnetic disk storage) for secondary storage. [1] The system was publicly announced on September 14, 1956, [2] [3] with test units already installed at the U.S. Navy and at private corporations. [2]
FASTRAND I had a single drum. The large mass of the rotating drum caused gyroscopic precession of the unit, making it tend to spin on the computer room floor as the Earth rotated under it. Very few of these devices were delivered. FASTRAND II (the majority of units produced) had two counter-rotating drums to eliminate the gyroscopic effect. One ...
Close-up of bi-quinary indicators Memory drum from an IBM 650 Side view of an IBM 650 Console Unit. First computer in Spain (1959) now at National Museum of Science and Technology in A Coruña. The IBM 650 Magnetic Drum Data-Processing Machine is an early digital computer produced by IBM in the mid-1950s.
It had 256 words of memory, using Williams tubes, with each word being 37 bits. It had only seven basic operations: add, subtract, and fixed-point multiply; [2] comparison, data extraction, input and output. Several years later, drum memory was added. [3] When the SWAC was completed in August 1950, [4] it was the fastest computer in the world.
The FH880 drum memory unit was also supported as a spooling and file-storage media. Spinning at 1800 RPM, it stored approximately 300,000 36-bit words. The 1107, without any peripherals, weighed about 5,200 pounds (2.6 short tons; 2.4 t). [9]
The drum controller selected the proper head and waited for the data to appear under it as the drum turned. The IBM 650 had a drum memory of 1,000 to 4,000 10-digit words with an average access time of 2.5 milliseconds. Core memory from Project Whirlwind, circa 1951. Magnetic-core memory was patented by A Wang in 1951. Core uses tiny magnetic ...