Function 36h (54)        Get Disk Free Space

Returns the number of available clusters, and other information about
the disk in the specified drive.

On entry:      AH         36h
DL         Drive number (0=default, 1=A, 2=B, etc.)

Returns:       AX         Sectors per cluster
FFFFh if invalid drive specified
BX         Number of available clusters
CX         Bytes per sector
DX         Total number of clusters per drive


This function returns information similar to that provided by
Functions 1Bh and 1Ch, with three exceptions. This function:

    returns the number of available clusters;
    does not return a pointer to the media descriptor byte;
    returns an error code if the specified drive is invalid.

See also: 1Bh
See also: 1Ch
See also: 44h

36h (54) Get Disk Free Space