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:

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.

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

Some facts about the old map format:

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