INT 21 - ELRES v1.1 - INSTALLATION CHECK                                        
	AH = 2Bh
	CX = 454Ch ('EL')
	DX = 5253h ('RS')
Return: ES:BX -> ELRES history structure (see #01381)
	DX = DABEh (signature, DAve BEnnett)
Program: ELRES is an MS-DOS return code (errorlevel) recorder by David H.
	  Bennett which stores recent errorlevel values, allows them to be
	  retrieved for use in batch files, and can place them in an
	  environment variable
SeeAlso: AH=4Bh"ELRES",AH=4Dh


Format of ELRES history structure:
Offset	Size	Description	(Table 01381)
 00h	WORD	number of return codes which can be stored by following buffer
 02h	WORD	current position in buffer (treated as a ring)
 04h  N BYTEs	ELRES buffer