INT E0 - PCROBOTS v1.41 - "REGISTER_IFF" - REGISTER FRIEND/FOE IDENT STRING
	AX = 0027h
	BX:CX = 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. IFF string
Return: nothing
Note:	the IFF string may only be set once
SeeAlso: AX=0028h,AX=0029h