TC: int absread( int drive, int count, int start, void *buffer )

	- prototype in dos.h

	- reads absolute logical disk sectors
	- drive = (0=A:, 1=B:, 2=C:, ...)
	- count = # of sectors to read
	- start = beginning logical sector number
	- buffer = address of buffer
	- TC++ accounts for DOS 4.x+ long sector values while TC 2.0 and
	  earlier do not (see INT 25)
	- returns 0 if OK; -1 on error; errno has DOS error number