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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 ...
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:
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]
Floppy disk drives have sustained "disk-to-buffer" data transfer rates that are one or two orders of magnitude lower than that of HDDs. The sustained "disk-to- buffer " data transfer rates varies amongst families of Optical disk drives with the slowest 1x CDs at 1.23 Mbit/s floppy-like while a high performance 12x Blu-ray drive at 432 Mbit/s ...
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 ...
For a given shape, SA:V is inversely proportional to size. A cube 2 cm on a side has a ratio of 3 cm −1, half that of a cube 1 cm on a side. Conversely, preserving SA:V as size increases requires changing to a less compact shape.
In aerospace engineering, payload fraction is a common term used to characterize the efficiency of a particular design. The payload fraction is the quotient of the payload mass and the total vehicle mass at the start of its journey.
The specific weight, also known as the unit weight (symbol γ, the Greek letter gamma), is a volume-specific quantity defined as the weight W divided by the volume V of a material: = / Equivalently, it may also be formulated as the product of density, ρ, and gravity acceleration, g: = Its unit of measurement in the International System of Units (SI) is newton per cubic metre (N/m 3), with ...