Earlier than anything we must describe the file transfer area or DTA. With the intention of sequentially read we use the 14H function of the 21Hinterruption.The register to be read is the one which is described by the current block and register. The AL register goes back to the state of the operation, if AL holds a value of 1 or 3 it means we have reached the end of the file. Value of 2 means the FCB is incorrectly structured. Lest there is no fault, AL will contain the value of 0 and the fields of the current block and register are dated.