Notes on disc bios by jhs@

BSD & Linux do not use BIOS after booting, but they do BIOS compatibility
to boot from hard disk.

See http://www.win.tue.nl/%7eaeb/linux/Large-Disk.html
for a nice description, below is just my extracted notes.

I've read up to. XXXXXX Up to http://www.win.tue.nl/~aeb/linux/Large-Disk-4.html

INT13 BIOS
		Cylinder Head	Sector 
	Bits	10 	8	6
	Size	1024	256	63
	Range	0-1023	0-255	1-63 (not 0-63 or 1-64, so you lose 1)
	dc: 1024 256 63 * * p 16515072 512 * p 8,455,716,864
	
	AH:	Function;
	CH	Cylinder low 8;
	CL:7-6	Cylinder high 2;
	CL:5-0	Sector;
	DH	Head;
	DL	Drive (80h or 81h);

Convention: C/H/S=16383/16/63 for disks larger than 8.4 GB.

Extended INT13 :
	DS:SI points at a 16-byte Disk Address Packet that contains
	an 8-byte starting absolute block number

ATA IDE Specification:
		Cylinder, Head	Sector 
	Bits	16 	4	8	(some old BIOSes only have 12 bits /cyl)
	Size	65536	16	255 (not 256)
	Range	0-65535	0-15	1-255 (not 0-255 or 1-256, so you lose 1)

	dc: 65536 16 255 * * p 267386880 512 * p 136,902,082,560

ATA-6: 2^48 sectors

INT13 + ATA Combined Without Translation:
		Cylinder Head	Sector 
	Bits	10 	4	6
	Size	1024	16	63
	Range	0-1023	0-15	1-63 (not 0-63 or 1-64, so you lose 1)
	dc: 1024 16 63 * * p 1032192 512 * p 528,482,304

Translation started in 1994, sometimes called Large')

LBA mode: (0 upward, linear) = c*H*S + h*S + (s-1)

My 4G in laptop: Toshiba HDD2914H 7944/16/63