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  2. Density (computer storage) - Wikipedia

    en.wikipedia.org/wiki/Density_(computer_storage)

    Higher density means more data moves under the head for any given mechanical movement. For example, we can calculate the effective transfer speed for a floppy disc by determining how fast the bits move under the head. A standard 3½-inch floppy disk spins at 300 rpm, and the innermost track is about 66 mm long (10.5 mm radius). At 300 rpm the ...

  3. Disk density - Wikipedia

    en.wikipedia.org/wiki/Disk_density

    High density (HD) 3½-inch disks switch to a cobalt disk coating, just as with 5¼-inch HD disks. Drives use 700-oersted write heads for a density of 17,434 bpi. Extra-high density (ED) doubles the capacity over HD by using a barium ferrite coating and a special write head that allows the use of perpendicular recording. [1] [2]

  4. Area density - Wikipedia

    en.wikipedia.org/wiki/Area_density

    In the case of a disk seen face-on, area density for a given area of the disk is defined as column density: that is, either as the mass of substance per unit area integrated along the vertical path that goes through the disk (line-of-sight), from the bottom to the top of the medium:

  5. File Allocation Table - Wikipedia

    en.wikipedia.org/wiki/File_Allocation_Table

    While 86-DOS supported three disk formats (250.25 KB, 616 KB and 1232 KB, with FAT IDs 0xFF and 0xFE) on 8-inch (200 mm) floppy drives, IBM PC DOS 1.0, released with the original IBM Personal Computer in 1981, supported only an 8-sector floppy format with a formatted capacity of 160 KB (FAT ID 0xFE) for single-sided 5.25-inch floppy drives, and ...

  6. Disk (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Disk_(mathematics)

    In geometry, a disk (also spelled disc) [1] is the region in a plane bounded by a circle. A disk is said to be closed if it contains the circle that constitutes its boundary, and open if it does not. [2] For a radius, , an open disk is usually denoted as and a closed disk is ¯.

  7. Z-channel (information theory) - Wikipedia

    en.wikipedia.org/wiki/Z-channel_(information_theory)

    The channel capacity of the Z-channel with the crossover 1 → 0 probability p, when the input random variable X is distributed according to the Bernoulli distribution with probability for the occurrence of 0, is given by the following equation:

  8. Volume - Wikipedia

    en.wikipedia.org/wiki/Volume

    The statute standardized weight, length and volume as well as introduced the peny, ounce, pound, gallon and bushel. [ 4 ] : 73–74 In 1618, the London Pharmacopoeia (medicine compound catalog) adopted the Roman gallon [ 8 ] or congius [ 9 ] as a basic unit of volume and gave a conversion table to the apothecaries' units of weight. [ 8 ]

  9. Charge density - Wikipedia

    en.wikipedia.org/wiki/Charge_density

    In electromagnetism, charge density is the amount of electric charge per unit length, surface area, or volume. Volume charge density (symbolized by the Greek letter ρ) is the quantity of charge per unit volume, measured in the SI system in coulombs per cubic meter (C⋅m −3), at any point in a volume.