there are no heads sectors or cylinders on an optical drive - it's a continuous outward spiral.
Logical Block addressing for bigger hard drives on older systems - always enable
Computer boots but with many errors or hangs
http://www.ultimatepcrepair.com/news/10.html
The LBA or Logic Block Addressing settings may be set wrong when your computer has many errors, and if your computer is an older model. LBA is a method used by older PCs to support IDE hard disks larger than 504 megabytes.
Access your BIOS and check the LBA settings. If the LBA settings are not enabled, enter the BIOS and enable your LBA.
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http://www.pjrc.com/tech/8051/ide/#lba
Logical Block Addressing (LBA) is much simpler and easier to use than CHS, and it's supported by all modern drives. With LBA, the entire drive appears as one giant array of 512 byte sectors. To access any sector, you just use one 28 bit unsigned integer to specify which one you want. The numbering is zero based, so to read the MBR, you specify 0. The code uses a 32 bit parameter, with the upper 4 bits ignored.
The PC computer world has known a number of barriers regarding hard drive size, at 32M, 528M, 2G, and 8G. These limits have been due to the filesystems used by DOS/Windows, and the parameter passing between the BIOS and DOS/Windows, and how the bits were allocated in those parameters, between Cylinders, Heads and Sectors. This code passes a single 32 bit (LBA) number, instead of 24 bits (CHS) used in the legacy PC bios calls. If you're quick with binary numbers (I am not past 65536), you probably already know that 28 bits allows 268435456 512 byte sectors, which is 128 gigabytes in computer speak, or 137 gig for hard drive marketing speak. I wonder what they'll do when the LBA address space runs out. With IBM's new 75 gig drive, it won't be long...
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'Normal', 'LBA', and 'Large' BIOS Settings explained
http://www.regstevens.co.uk/add1.htm
One of the problems that can confuse newcomers to hard drive installation is the BIOS settings. The BIOS in most modern PCs can set the hard disc parameters up itself automatically without much assistance from the user. However, those from a few years back still rely on the user choosing the optimum settings. The thing that confuses most people is the choice offered of 'Normal', 'LBA' or 'Large'. These are to do with the way the BIOS manages the addressing of the disc. Good old DOS (Disk Operating System- remember that?) addresses the 'disc' in terms of Cylinder number, Head, number, and Sector number. Now when DOS was written hard drives were modest beasts of a few megabytes which were thought of as pretty cool at the time. No one imagined the explosion in sizes the technology would be exposed to within a few years, nor the memory guzzling bloatware that would drive the requirement. As 'windahs' is still really DOS at heart this gives us a problem. 'Normal' disc addressing has 24bits allocated to it as follows:- 10 bits (1024)- cylinders; 8 bits (256)- heads; 6 bits (64)- sectors
Since a sector is 512 bytes in size, you can work this out to be 1024 X 256 X 63 X 0.5kB = 256k X 32kB = 8GB (or thereabouts)
Now, they obviously got carried away here because normal discs don't really have that many heads- 16 is usually top whack. So unfortunately 'Normal' maximum corresponds to 1024 X 16 X 63 X 0.5kB = 512MB (nearly)
You only get 63, not 64 sectors for the price of your 6 bits here as '000000' is not useable.
The upshot of this is that if your BIOS offers you 'Normal' and you accept it, then you will only be able to use 500MB of that expensive hard drive you've just bought- even a 40GB drive is unlikely to have more than 16 heads!
Now, following the introduction of discs exceeding 512MB, someone thought of the good idea of getting the BIOS to kid DOS that it was using those spare head addresses but actually 'translating' these into reality i.e. actually more sectors. Thus, 'ECHS' (Extended Cylinders Heads Sectors Addressiung) was born. It worked well up to the point that we ran out of the spare head addressing. Most BIOS could take us all the way to 8GB, though a few may have problems at 2GB. Unfortunately, not all BIOS's call it ECHS- you may find it referred to simply as 'Large'.
Beyond 8GB we have to use 'LBA' which involves a much more complicated process to get at those extra sectors on modern drives. Basically this works because the operating system dispenses with CHS altogether and simply refers to 'Logical Blocks' instead. It's very reliant on the BIOS and the hard drive itself translating the LBA into something the drive understands. Some BIOS's with LBA will still limit you to 8GB, but if you want to address more than 8GB then only LBA offers the possibility. So choose 'Large' in your BIOS only if you've a drive between 500MB and 8GB. In order to address more than 8GB the Operating System, the BIOS and the hard drive all have to conspire to make it possible. If you are in doubt about what your motherboard offers then consult its handbook or the manufacturer's web site for information. Don't forget that older operating systems- like DOS 6.2, for example, can't play this game because they are tied to the old CHS addressing method.
Linear Mode
