Format of environment block:
Offset	Size	Description	)
 00h  N BYTEs	first environment variable, ASCIZ string of form "var=value"
      N BYTEs	second environment variable, ASCIZ string
	...
      N BYTEs	last environment variable, ASCIZ string of form "var=value"
	BYTE	00h
---DOS 3.0+ ---
	WORD	number of strings following environment (normally 1)
      N BYTEs	ASCIZ full pathname of program owning this environment
		other strings may follow