TC: void getfatd( struct fatinfo *fatblkp )

	- prototype in dos.h

	- returns information from the file allocation table for the
	  DEFAULT drive into fatblk
	- structure fatinfo is defined as:

	struct fatinfo
	    char  fi_sclus;		- sectors per cluster
	    char  fi_fatid;		- media descriptor byte  from FAT
	    int   fi_nclus;		- cluster on disk
	    int   fi_bysec;		- bytes per sector

	- closest MS C function is _dos_getdiskfree()
	- see	INT 21,1B   getfat()