Added README

README

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+FREESP -- Chartreuse 2021
+
+Calculates the free space on a FAT 16 disk very fast. 
+On XT Class systems with large FAT 16 hard disks the initial DIR 
+command can take upwards of 15-30 seconds to complete, this is due to 
+the slow method that DOS uses for calculating free space on the hard
+disk.  However once DOS has calculated this value it stores a cache of 
+it which it keeps updated unless an application does raw disk accesses
+such as CHKDSK.  This means that every subsequent DIR will take no time
+to display free space.  This program is designed to quickly calculate 
+the free space on the disk by reading through the FAT and counting up
+the used clusters then calculating the total number of clusters on the 
+disk and subtracting to get the number of free clusters.  Once 
+calculated this value is stored into the Disk Parameter Block from DOS
+in the field storing the free clusters which DIR uses for calculating 
+free space.  With a 2GB FAT 16 partiton on a CF card in an XTIDE 
+on my Turbo XT (running at 4.77MHz) this program takes <2s to complete
+while the initial DIR call takes 25s. 
+
+This program should run on any PC or compatible with DOS 4.0 or later
+it has only been tested on MS-DOS 6.22. This program should be unneeded
+on DOS 3.2 and earlier as DIR does not perform a free space calculation,
+as well these versions also use FAT12 for disks which DOS keeps more 
+metadata in memory and will avoid the slowdown.  It requires 66kB of 
+free memory to run, but once complete does not use any, it is not a TSR.
+
+Usage
+------------
+
+FREESP <A-Z>
+
+Example:
+FREESP C
+
+This will pre-calculate free space on the C partition. I recommend
+putting this program into your AUTOEXEC.BAT for each partition on your
+system. If you are using 4DOS then you'll want to do this as 4DOS will
+perform the free-space calculation before the running of a command
+when it has to search the PATH.
+
+Assembling
+--------------
+This program was created to assemble under Borland Turbo Assembler 2.01
+with Borland Turbo Link 2.0
+
+TASM FREESP.ASM
+TLINK /T FREESP.OBJ
+
+This will produce FREESP.COM
+
+