FILE CONCEPTS BIT:- This stands for BINARY DIGIT. It is the unit used in binary representation. BYTE:- A sequence of bits operated upon as a unit and usually shorter than a computer word. A byte is a character and is equal to 8 bits (which means 3 bytes are three characters and are equal to 24 bits). CHARACTER:- This is a number or a letter or a symbol e.g. L, 4, +, etc. WORD:- A group of characters occupying one storage location in a computer. It is treated by the computer circuits as an entity, by the control unit as an instruction, and by the arithmetic units as a quantity. FIELD:- This is a combination of related characters. RECORD:- This is a combination of related fields. More precisely, a collection of related items of data (fields) located as a unit. FILE:- This is a collection of related records. An organized, named collection of records treated as a unit, or the storage device on which these records are kept. DATABASE:- A non redundant collection of interrelated data file items. TYPES OF FILES There are four basic types of files. . Transaction file:- This a temporary file that represents sales orders for a day in selling merchandise business. . Master file:- This is a file that is fairly permanent in nature e.g. A file that contains records of employees for a company. . Reference file:- This is a file that is semi permanent. An example is a file containing price list. . Historical file:- This is a permanent file. FILE PROCESSING This refers to the various activities that can the carried out on the record of a file. Some of these processing activities are:- . Sorting:- This is the arrangement of the records of a file in ascending or descending order. . Merging:- This is the combination of two or more files into a single file. . Validation:- This is a programming technique of carrying out logical check on the data being captured on the computer. . Referencing:- This is the accessing of a particular record of a file on order to ascertain its contents. . File maintenance:- This refers to the addition of new records or deletion of obsolete records or modification of existing records. . Updating:- This is the process of making the master file to reflect the most current situation. . File enquiry or interrogation:- This is very similar to referencing. It is ascertaining the content of the file for decision-making purposes. . Searching:- This is the process of looking through a set of record on the file with a view to making use of those record that have similar characteristics. FILE ORGANISATION There are four methods by which file can be organized on a magnetic disk. . Serial:- In this method, records and written into the tape one after the other without any regard to the order of the record key. . Sequential:- In this method, records are first sorted according to a particular order of the record keys before being written on the disk one after the other. . Indexed sequential:- In this method, an index is created on the disk indicating the address or location of each record as it is being written into the disk. . Random:- In this method, records are written into the disk any how. But a mathematical formula is put in place by programming technique in such a way that the formula yields the location or address of a particular record whenever as key field is substituted. OTHER FILE CHARACTERISTICS/ADDRESS CONCEPTS . Volatility:- This is the frequency with which records are added to a file or deleted from it. . Size:- This is the amount of date stored in a file. . Growth:- This refers to increase in the size of a file as records are being added. . Cylinder:- This is the major sub-division of a disk. . Track:- Each cylinder is made up of a certain number of tracks. . Sector:- This is the smallest addressable park of a disk, it is also called Block.