9th Class Computers Science Classification of Computer and Number System Data Access Methods

    Data Access Methods

In computer science data access method is a hardware mechanism or computer program that moves data between the computer and storage device, such as hard disk, floppy and CD. Basically there are two types of data access methods.  

  They are the following: 

• Sequential Access Method
• Direct Access Method  

  Sequential Access Method

In this method records must be read in the same order as they were written to the storage media. The computer begins searching for a record in the file and then sequentially examining the next record and so on until the required record is located. The best example of these kinds of storage media is magnetic tape. The magnetic tape allows only sequential access to data. While searching a record on a reel of magnetic tape, the tape must be read sequentially, beginning with the first record.  

 Direct Access Method

This method allows immediate direct access to individual records in a file. There are several techniques used to accomplish direct-access file organization. Magnetic disks, such as CD is the most commonly used devices for storing direct-access files. Direct access file organization must be used whenever the application requires immediate access to individual records. It is widely used today whenever the computer configuration includes CRT (Cathode Ray Tube) terminals that display management information on demand.