areal density

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areal density

[‚er·ē·əl ′den·səd·ē]
(computer science)
The amount of data that can be stored on a unit area of the surface of a hard disk, floppy disk, or other storage device.

areal density

The number of bits per square inch of storage surface. It typically refers to disk drives, where the number of bits per inch (bpi) times the number of tracks per inch (tpi) yields the areal density.

From 2,000 to 100,000,000,000 Bits
The areal density of disk storage devices has increased dramatically since IBM introduced the RAMAC, the first hard disk computer in 1956. RAMAC had an areal density of two thousand bits per square inch, while current-day disks have reached 100 billion bits (100 gigabits per square inch). Perpendicular recording is expected to increase storage capacity even more dramatically. See perpendicular recording, superparamagnetic limit, holographic storage and AFM.

Rings on Dumbbells for Denser Memory

The areal density of memory chips is much greater than that of magnetic disks. However, in 2006, the California Institute of Technology built a prototype memory chip that used molecular switches resembling dumbbells with a ring that slides along the center bar. Voltage pushes the ring from one end to the other to represent a 0 or 1. Only in the early stage of development, the first prototype chip was no larger than a white blood cell and held 160,000 bits. If it were to become commercially viable, the density would exceed 600 billion bits per square inch. In addition, scientists claimed that improvements in this technology are expected that could make the bits 10 times denser. Such an achievement would yield six trillion bits per square inch!
References in periodicals archive ?
1]) of the efficiency of fishing nets for each studied species was calculated and used in the swept area density calculations.
Tenders are invited for Wire Bpvlz 70 Mmsq Ty-16-505-911-76 Braid Surface Area Density Above 95%
Agglomeration effects are observed in all four countries, but they were noticeably stronger in India and strongest in China, especially with regard to area density.
To assess the microvessel density, highly vascularised foci ('hot spots') after immuno-staining with CD34 were quantified for number of vessels per square millimetre and for vascular surface area density.
Leaf area index (LAI) and Leaf area density (LAD) is an indicator used to study the thermal conversion of the trees with its environment [13].
Given that the required area density of dust particles is 0.
Here, we will use explicit formulae for the spherical contact distribution function to derive formulae for the volume and surface area density of the dilated system of cell facets.
Surface area density can be increased by inserting the secondary fins of various shapes i.
Modeling approaches include three-dimensional Eulerian simulation of a gas-solid bubbling fluidized bed, modeling of solidification of binary fluids with non-linear viscosity models, numerical simulation of gas-solid flow by computational fluid dynamics techniques, modeling of stratified two phase flows using an interfacial area density model, and modeling of segregation and mixing effects in a riser using the quadrature method of moments.
Vascularity was determined for mammary tissue with the following measurements taken: the cross-sectional capillary area density (CAD, total capillary area as a proportion of tissue area), capillary number density (CND, total number of capillaries per unit of tissue area), and capillary surface density (CSD, total capillary circumference per unit of tissue area).
The past decade has witnessed a thousand-fold increase in magnetic recording area density, which has revolutionized the way information is stored and retrieved.
On the basis of statistical trends observed in cities across Canada and the US, this paper first identifies the absence of core area density alongside overall low-density profiles as generic features of most, though not all, mid-size urban areas.

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