When you format a hard drive, be it an ADFS drive or a SCSI drive, you can choose between "Old map" and "New map" formats. To see which format your hard drive is in, type

*ADFS:Map :4

(or :5, 6 or 7)

If the output says "new map", you've got a new map format.

Some facts about the new map format:

• this format has the ability to store smallish files within the space taken on the disc by the directory. The maximum size of these files is the value given to the LARGE FILE ALLOCATION UNIT, or LFAU.
• the LFAU is specified when you format the hard drive. Apart from specifying the maximum size of a file which can be fitted within a directory space (NB *NOT* the maximum size of a file which can be stored on the disc), it is also related to the CAPACITY of the drive.

The larger the drive, the higher the LFAU needs to be in order for the drive to be able to be formatted. The following is a table of disc sizes versus possible LFAUs:

 Capacity LFAU "Size" of a directory (approx)
 ======== ==== ==============================
 Up to 124Mbytes 256 4K
 Up to 249Mbytes 512 8K
 Up to 499Mbytes 1024 16K
 Up to 999Mbytes 2048 32K

The "up to" values are inclusive. You can, of course, specify a large LFAU, but the side effect is that the larger the LFAU, the more disc space a directory takes, hence the "wasted disc space".

This arrangement, therefore, allows files up to the LFAU to be stored on the disc without taking up any more disc space, and without fragmenting the disc too much.

• when saving files to a new format disc, FileCore will automatically try and coalesce blocks to avoid fragmentation.
• to determine what value LFAU your drive has:

DIM block% 64
SYS"ADFS_DescribeDisc",":4",block%
P."LFAU is ";2^(block%?5)

Some facts about the old map format:

• each directory always takes 4Kbytes
• the disc is not automatically compacted.

Note that ALL of the above applies to any FileCore based filing system. This includes ADFS and SCSIFS.