Disk Copy Fast

Disk Copy Fast (DCF) is a file archiver software utility that creates disk images of floppy disks. It also refers to the file format used to encode the disk image files created. These image files typically use the file extension ".DCF".

File format information

DCF files contain a file header plus a raw image of the floppy disk encoded as a bit stream of the first sector to the last sector imaged. Sectors are imaged from track 00 sector 00 to the last sector recorded. The DCF software by default only records sectors up to the last track used by the file system as specified in the file allocation table.

DCF format is not compatible with Rawrite (.ima) or .IMG file format.

Software information

Disk Copy Fast and its professional/commercial version Disk Copy Plus were authored by Chang Ping Lee. The last known version is 5.3a released in 1996. This software does not run well under Windows XP or newer. This software may be abandonware.

If you have files saved in this format, WinImage from Gilles Vollant Software will extract them. http://www.winimage.com/

Distributed coordination function

Distributed coordination function (DCF) is the fundamental MAC technique of the IEEE 802.11 based WLAN standard. DCF employs a CSMA/CA with binary exponential backoff algorithm.

DCF requires a station wishing to transmit to listen for the channel status for a DIFS interval. If the channel is found busy during the DIFS interval, the station defers its transmission. In a network where a number of stations contend for the wireless medium, if multiple stations sense the channel busy and defer their access, they will also virtually simultaneously find that the channel is released and then try to seize the channel. As a result, collisions may occur. In order to avoid such collisions, DCF also specifies random backoff, which forces a station to defer its access to the channel for an extra period. The length of the backoff period is determined by the following equation:

DCF also has an optional virtual carrier sense mechanism that exchanges short Request-to-send (RTS) and Clear-to-send (CTS) frames between source and destination stations during the intervals between the data frame transmissions.

Design rule for Camera File system

Design rule for Camera File system (DCF) is a JEITA specification (number CP-3461) which defines a file system for digital cameras, including the directory structure, file naming method, character set, file format, and metadata format. It is currently the de facto industry standard for digital still cameras. The file format of DCF conforms to the Exif specification, but the DCF specification also allows use of any other file formats.

The latest version of the standard is 2.0 (2010 edition).

File system

In order to guarantee interoperability, DCF specifies the file system for image and sound files to be used on formatted DCF media (like removable or non-removable memory) as FAT12, FAT16, FAT32, or exFAT. Media with a capacity of more than 2 GB must be formatted using FAT32 or exFAT.

The DCF standard defines that the "Read Only" file and directory attribute of FAT file systems can be used to protect files or directories from accidental deletion. Other existing attributes don't have any specially defined usage in DCF.