Format of HMA Memory Block (DR DOS 6.0 kernel loaded in HMA):
Offset	Size	Description	)
 00h	WORD	offset of next HMA Memory Block (0000h if last block)
 02h	WORD	size of this block in bytes (at least 10h)
 04h	BYTE	type of HMA Memory Block (interpreted by MEM)
		00h system
		01h KEYB
		02h NLSFUNC
		03h SHARE
		04h TaskMAX
		05h COMMAND
 05h	var	TSR (or system) code and data. DR DOS TSR's, such as KEYB,
		  hooks interrupts using segment FFFEh instead FFFFh.