INT 21 - LANtastic - LOGIN TO SERVER                                            
	AX = 5F81h
	ES:DI -> ASCIZA NUL-terminated ASCII string.	The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h.  Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL. login path followed immediately by ASCIZA NUL-terminated ASCII string.	The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h.  Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL. password
	BL = adapter number
	    FFh try all valid adapters
	    00h-07h try only specified adapter
Return: CF clear if successful
	CF set on error
	    AX = error code
Notes:	login path is of form "\\machine\username"
	if no password is used, the string at ES:DI must be terminated with
	  three NULs for compatibility with LANtastic v3.0.
SeeAlso: AX=5F82h,AX=5F84h