Operating system

 * File Access Method:- the way that access and read into memory is determined by access method usually single access method is supported by a system while there are operating systems that support multiple access method.

(a) Sequential Access in sequention access data is Access are record right after another in an order. The read cammand cause a pointer to be moved ahead by one. The right command a llocate spece for the record move the pointer to the new and of the file. Some examples sequential access are found in magnetic tab,

(b) Direct Access:- This method is useful to disk. The is viewed as a Number sequence of blocks or record. There are no restriction on which are read/write, unlike sequential access, read or write operation can be performed in any order this method is usually used in database.

(c) Indexed Access:- The indexed method and it obtains the pointer to various blocks of the file show to find a record inside a file we first search the inside and later use the pointer obtained to access the file directly and find the record have been search for.