Format of ESDI Device Status Block:
Offset	Size	Description	)
 00h	BYTE	08h
 01h	BYTE	number of words in block (09h)
 02h	BYTE	error flags
 03h	BYTE	unused
 04h	BYTE	command error code (see #00255)
 05h	BYTE	command status code (see #00256)
 06h	WORD	ESDI standard status
 08h  5 WORDs	ESDI vendor-specific status codes