The tests of the file system will assume the following sizes of the 
disk and the internal data structures:

Disk: 4 cylinders, 2 surfaces, 8 sectors/track, 64 Bytes/sector

File name: maximum of 4 characters, no extension

Number of files: not more than 10

Number of open files: 3 plus the directory, i.e., the size of the OFT is exactly 4 entries. 
The directory should be opened automatically (with index=0) when the file system starts, i.e., whenever the command "in" is issued.