Wednesday, August 29, 2007

Mobile phone

A mobile telephone or cellular telephone is a long-range, portable electronic machine used for mobile communication. In addition to the normal voice function of a telephone, current mobile phones can carry many additional services such as SMS for text messaging, email, packet switching for access to the Internet, and MMS for sending and getting photos and video. Most current mobile phones connect to a cellular network of bottom stations, which is in turn interconnected to the public switched telephone network.
Mobile news services are increasing with many organizations providing on-demand news armed forces by SMS. Some also provide instant news pushed out by SMS. Mobile telephony also facilitates activism and public journalism being explored by Reuters and Yahoo and small sovereign news companies such as Jasmine News in Sri Lanka. Also companies like Monster are starting to offer mobile services such as job search and career information.
The total worth of mobile data services exceeds the value of paid services on the internet, and was worth 31 B dollars in 2006. The largest categories of mobile services are music, picture downloads, video gaming, adult entertainment, gambling, video/TV.

Friday, August 17, 2007

Table

In relational databases, SQL databases, and flat file databases, a table is a set of data elements that is controlled using a model of horizontal rows and vertical columns. The columns are identified by name, and the rows are identified by the values appearing in a particular column division which has been identified as a candidate key. Table is another term for family although there is the difference in that a table is usually a multi-set of rows whereas a relation is a set and does not allow duplicates. A table has a particular number of columns but can have any number of rows. Besides the actual data rows, tables generally have related with them some meta-information, such as constraints on the table or on the values within particular columns.
The data in a table does not have to be actually stored in the database. Views are also relational tables, but their data is considered at query time. In non-relational systems, such as hierarchical databases, the isolated counterpart of a table is a structured file, representing the rows of a table in each record of the file and each column in a record.

Wednesday, August 08, 2007

Software

Software, consisting of programs, enables a computer to perform specific tasks, as opposed to its physical components which can only do the responsibilities they are mechanically designed for. The term includes application software such as word processors which perform helpful tasks for users, system software such as operating systems, which interface with hardware to run the necessary services for user-interfaces and applications, and middleware which controls and co-ordinates distributed system.
Computer software has to be loaded into the computer's storage space ( memory or RAM). Once the software is loaded, the computer is able to implement the software. Computers control by executing the computer program. This involves passing instructions from the application software, through the system software, to the hardware which finally receives the instruction as machine code. Each instruction causes the computer to carry out an operation moving data, transport out a computation, or altering the control flow of instructions.