Filename: WD340LBA.TXT
WWW URL: http://www.firmware.com/support/bios/wd340lba.htm
FTP URL: ftp://ftp.firmware.com/text/wd340lba.txt
Revision: 03/05/98 TLS Micro Firmware Technical Support
Summary: Explains how LBA translation is used in some BIOSes even
when a drive does not need translation.
We have found that the AMI/Intel BIOSes used on Intel motherboards such as the Batman, Batman's Revenge and Plato will perform LBA translation on any hard drive, regardless of size, if LBA translation is selected in CMOS setup. On the older type of AMI BIOS with a main menu screen, LBA translation is enabled on the second screen. On the newer type of AMI BIOS with a menu bar across the top of the screen, there is an option for translation type on the submenu for each drive. LBA translation is enabled by setting the translation type to AUTO or to LBA. Note that in some of these BIOSes, translation is disabled if the drive is set up as User-Defined rather than Auto-Configured.
On Phoenix BIOSes, such as our BIOS upgrades, hard drives not needing translation (under 528MB) are not translated. Normally, the end result would be the same whether a drive under 528MB is translated or not. Also, on drives between 528MB and 4.2GB, the effect is the same whether the BIOS uses LBA translation or ECHS translation. However, the above two statements assume that the drive has 16 heads and 63 sectors per track.
The Western Digital 340MB drive uses factory CHS parameters of 1010 cylinders, 12 heads, and 55 sectors. LBA translation always adjusts to 16 heads and 63 sectors. If this drive is setup in an Intel/AMI BIOS using LBA translation, the BIOS will use translated CHS values of 661 x 16 x 63. In this case, however, the values shown in CMOS setup will be 1010 x 12 x 55.
When the BIOS is then upgraded with a Micro Firmware Phoenix BIOS, our install program will carry over the CHS values in use, and these values will be shown in CMOS setup (661 x 16 x 63). The drive will then continue to operate normally. If the drive is then autotyped, though, the factory CHS values of 1010 x 12 x 55 will be used and the drive will not boot. Actually, it would probably be preferable to set the drive up normally (autotype it) and repartition and reformat it. There is no harm in leaving it at 661 x 16 x 63, except that if CMOS values are ever lost and the drive is autotyped, it will not be accessible.
So there are a couple of things to keep in mind here. First of all it would be good to have a look in the original BIOS before upgrading to determine if LBA translation is enabled. Secondly, after upgrading to the Phoenix BIOS, have a look in CMOS setup and record the values that the Install program has put there. If these are not the factory values, they should be recorded in case needed later.
Note that all of the above would apply to any other hard drive under 528MB (504 binary MB) that does not use 16 heads and 63 sectors. Gateway 2000 used only Western Digital drives at that time. There is also a 425MB Western Digital drive which uses CHS values of 989 x 15 x 56. The translated LBA Assist values would be 824 x 16 x 63. The next drive up is the 540MB (1048 x 16 x 63), so we are mainly concerned with the 340MB and 425MB drives and any smaller drives.
When investigating this type of problem, it can be useful to look at the partition table. A program on our ftp site can be used for this. The program is called PARTINFO and is in a self-extracting ZIP file named PINFO.EXE in the UTILS directory.