Format of Windows95 HMA memory control block:
Offset	Size	Description	)
 00h  2 BYTEs	signature "MS" (4Dh 53h)
 02h	WORD	segment of owner (or segment at which to address block???)
		0000h = free
		0001h = DOS???
		FF33h = IO.SYS
		FFFFh = MSDOS.SYS
 04h	WORD	size of memory block (not including this header)
 06h	WORD	offset of next memory block in segment FFFFh, or 0000h if last
 08h  8 BYTEs	unused (explicitly set to 0 for MS-DOS 7.10)