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 ?
Improvements in the head and the magnetic layer of the disk increase areal density.
For the past several years, areal density demonstrations have grown in excess of 100 percent per year.
It is likely that the rate of increase for magnetic disk areal density will start to drop below historical rates annually, due to the greater difficulty in making the new technology work.
In its Corporate Research labs last year, Sony provided the first demonstration of a breakthrough in tape storage areal density by achieving 6.
5-inch HDD based on PMR, with the industry's highest areal density of 178.
It has an areal density of 30Gbit per square inch, and a low power consumption level of 11 watts.
5-inch HDD, Toshiba continues to lead the industry through such breakthrough products as the 200GB MK2035GSS, which offers the highest areal density yet achieved(4) using PMR technology and the industry largest capacity(5) in 9.
They adopted it for their own needs in order to increase the areal density of their digital tape media.
This areal density, demonstrated in laboratory testing, represents an increase of more than two-and-a-half times the areal density of today's highest-capacity products.
Engineers at companies like IBM continue to increase the areal density (the amount of data that can be stored in a given amount of physical space) of magnetic platters to the point where projections indicate a few dollars per gigabyte in several years.
Veeco's NEXUS PVD multi-target system is used to deposit high-quality, extremely uniform, thin film multi-layer stacks and will be used by the customer to manufacture high areal density Tunneling Magneto-Resistive (TMR) heads.
5-inch drives, offering areal density for computers.