Date   : Tue, 05 Apr 1983 03:36:00 EST
From   : Ronald G. Fowler <RGF@mit-mc.arpa>
Subject: more than 256 files/disk

  Yes, you can have much more than 256 files on a disk; set the
DIRMAX field in your BIOS to whatever you'd like.  There is a
catch however: you must reserve sufficient space for the directory 
via AL0 and AL1; since these two bytes form a 16-bit vector which
is used to initialize the allocation vector, your directory maximum
size is 16 blocks (which may vary from 1K to 16K, depending on how
BLKSHF and BLKMSK are set up).  Hence, with 1K blocks, your dir-
ectory cannot exceed 16K (16 1K blocks; since there is room in a 1K
block for 32 32-byte directory entries, 512 would be the maximum
directory size when using 1K blocks).

Note that you can increase the directory size only be enlarging the
block size, and this is at the expense of efficiency when considering
small files.

               --Ron Fowler