File Allocation Table

File Allocation Table (FAT) is a computer file system architecture and a family of industry-standard file systems utilizing it. The FAT file system is a legacy file system which is simple and robust. It offers good performance even in light-weight implementations, but cannot deliver the same performance, reliability and scalability as some modern file systems. It is, however, supported for compatibility reasons by nearly all currently developed operating systems for personal computers and many mobile devices and embedded systems, and thus is a well-suited format for data exchange between computers and devices of almost any type and age from 1981 up to the present.

Originally designed in 1977 for use on floppy disks, FAT was soon adapted and used almost universally on hard disks throughout the DOS and Windows 9x eras for two decades. As disk drives evolved, the capabilities of the file system have been extended accordingly, resulting in three major file system variants: FAT12, FAT16 and FAT32. The FAT standard has also been expanded in other ways while generally preserving backward compatibility with existing software.

Hard disk drive

A hard disk drive (HDD), hard disk, hard drive or fixed disk is a data storage device used for storing and retrieving digital information using one or more rigid ("hard") rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. HDDs are a type of non-volatile memory, retaining stored data even when powered off.

Introduced by IBM in 1956, HDDs became the dominant secondary storage device for general-purpose computers by the early 1960s. Continuously improved, HDDs have maintained this position into the modern era of servers and personal computers. More than 200 companies have produced HDD units, though most current units are manufactured by Seagate, Toshiba and Western Digital. As of 2015, HDD production (exabytes per year) and areal density are growing, although unit shipments are declining.

USB flash drive

A USB flash drive, also known under a variety of other names, is a data storage device that includes flash memory with an integrated USB interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. Most weigh less than 30 grams (1.1 oz).As of January 2013, drives of up to 512 gigabytes (GB) were available. A one-terabyte (TB) drive was unveiled at the 2013 Consumer Electronics Show and became available later that year. Storage capacities as large as 2 TB are planned, with steady improvements in size and price per capacity expected. Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and have a 10-year shelf storage time.

USB flash drives are often used for the same purposes for which floppy disks or CDs were once used, i.e., for storage, data back-up and transfer of computer files. They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts. Additionally, they are immune to electromagnetic interference (unlike floppy disks), and are unharmed by surface scratches (unlike CDs). Until about 2005, most desktop and laptop computers were supplied with floppy disk drives in addition to USB ports, but floppy disk drives have become obsolete after widespread adoption of USB ports and the larger USB drive capacity compared to the 1.44 MB 3.5-inch floppy disk.

NTFS

NTFS (New Technology File System) is a proprietary file system developed by Microsoft. Starting with Windows NT 3.1, it is the default file system of Windows NT family.

NTFS has several technical improvements over FAT and HPFS (High Performance File System), the file systems that it superseded, such as improved support for metadata, and the use of advanced data structures to improve performance, reliability, and disk space utilization, plus additional extensions, such as security access control lists (ACL) and file system journaling.

History

In the mid-1980s, Microsoft and IBM formed a joint project to create the next generation of graphical operating system. The result of the project was OS/2, but Microsoft and IBM disagreed on many important issues and eventually separated: OS/2 remained an IBM project and Microsoft worked on Windows NT.

The OS/2 file system HPFS contained several important new features. When Microsoft created their new operating system, they borrowed many of these concepts for NTFS. Probably as a result of this common ancestry, HPFS and NTFS use the same disk partition identification type code (07).

Secure Digital

Secure Digital (SD) is a non-volatile memory card format developed by the SD Card Association (SDA) for use in portable devices. The standard was introduced in August 1999 as an improvement over MultiMediaCards (MMC), and has become the de facto industry standard.

Secure Digital includes four card families available in three different form factors. The four families are the original Standard-Capacity (SDSC), the High-Capacity (SDHC), the eXtended-Capacity (SDXC), and the SDIO, which combines input/output functions with data storage. The three form factors are the original size, the mini size, and the micro size. Electrically passive adapters allow a smaller card to fit and function in a device built for a larger card.

There are many combinations of form factors and device families, although as of 2013, the prevailing formats are full- or micro-size SDHC and full or micro SDXC.

The SDA uses several trademarked logos to enforce compliance with its specifications and assure users of compatibility.