Format of National Semiconductor PC87415 IDE DMA-Master configuration:
Offset	Size	Description	)
 00h 64 BYTEs	header (see #00878)
		(vendor ID 100Bh, device ID 0002h)
 40h  3 BYTEs	control register
 43h	BYTE	write buffer status (read-only)
 44h	BYTE	Channel 1 master read timing
 45h	BYTE	Channel 1 master write timing
 48h	BYTE	Channel 1 slave read timing
 49h	BYTE	Channel 1 slave write timing
 4Ch	BYTE	Channel 2 master read timing
 4Dh	BYTE	Channel 2 master write timing
 50h	BYTE	Channel 2 slave read timing
 51h	BYTE	Channel 2 slave write timing
 54h	BYTE	command and control block timing
 55h	BYTE	sector size
!!!http://www.national.com/ds/PC/PC87415.pdf p.8
SeeAlso: #00739,#00921