These  superseded  functions operate on the DOS default directory only.
In most cases, it is wise to use the Handle-Oriented File I/O functions.

16H create file                   29H parse text into FCB-type filename
0fH open file                     11H  12H search current directory via FCB
10H close file                             (may be used in CVF  spelunking)
13H delete file

14H read sequential file
15H write sequential file

21H read record from random access file
27H read multiple records from random access file

24H set random record block field size
22H write record to random access file
28H write multiple-records to random access file (also change file size)

                                                                              

FCB File I/O Functions