Owlcom software
basadO wlCom  Software
Let's Owl manage your files
Welcome Screenshots Buy now Download Write to Owl Subscribe to news FAQ Links

Organization of the file system

ASCII files contain text strings that can be printed, viewed on the screen or edit ordinary text editor. Another type of binary files-files, means that this is not ASCII files. Usually they have some internal structure. For example, workable Unix file has five sections: header, text, data, and symbolic bits reallokatsii table. OS performs file only if it has the desired format. Another example might be a binary file backup. Typing files is not too strict. Normally, applications, working with files, file type to recognize his behalf in accordance with generally accepted agreements. For example, files with the extensions. C,. Pas,. Txt-ASCII files, files with the extensions. Exe-, executable files with the extensions. Obj,. Zip-binary, etc. Apart from the name of the OS is often linked to each file, and other information, such as modification date, size, etc. These other characteristics are called the attributes of the files. The list of attributes may vary from one operating system to another. It may include: attributes protection, password, the name of the creator, flags secrecy, arhivnosti, sistemnosti, binarnosti, type of access, length record, key position, time, date, size, etc. This information is usually stored in the directory structure (see section realization directories), or other structures that provide access to the data file. Access to files In order to use the information stored in files, it should be read in memory of the computer. There are several ways to access files. Early OS provide only one-way serial access (model tape). Record OCR in order of receipt. Current position readers can be returned to the top of the file (rewind). However, magnetic disks and drums appeared files with direct access (random). For spetsifitsirovaniya point where must begin reading are used two ways: from the start, or with the current position, which gives seek operation. Serial access based on the model of tape and works as a consistent access devices, as well as direct. This is the most common model. The Organization of direct access essential for many applications, such as for database management systems. Not all systems support both (consistent and direct) access method. Serial emulate easy access through direct, but the realization of the direct access via serial would be very inefficient. In addition to direct and consistent, there are other methods of access. Typically, they include construction of the index file and based on the direct access method. To search for records at the outset makes the index, which is the index to a record.
Next part
Welcome    Screenshots    Download    Buy now Write to Owl    Subscribe to Owl news   FAQ   Links  
Copyright 2004-2008 OwlCom Software .

OISV - Organization of Independent Software Vendors - Contributing Member Software Submit .NET - FREE and PREMIUM search engines submission and software submission and software promotion service. Owl Commander
Locations of visitors to this page

Valid HTML 4.01 Transitional