Yes. Often these drivers are essential to get any kind of performance out of your interface.
The PIO or DMA mode used when transferring data is determined by the interface card. Some cards have jumpers that determine the speed in hardware; these work in the fast mode from the microsecond you switch on the computer.
Most interfaces, however, are software configurable. At bootup, they default to the slowest possible speed. Somewhere during the boot process, a piece of software belonging to your adapter figures out what kind of transfer rates the drives support and configures the controller chip to match. There are a couple of cases to distinguish:
Usually, there are drivers for other operating systems as well, such as Windows, Win95, OS/2 and so forth. These serve a couple of purposes.
*wdctrl
) that ships with
Windows and Windows for Workgroups has some serious restrictions. See
Q
8.10
for details.In view of this it is rather unfortunate that so often, the drivers supplied with an interface are of mediocre quality.
The difference between the three is this.
Note. Some BIOSes have a braindead Large implementation which works only for disks of up to 1GB. Fortunately, all larger disks support LBA.
WARNING. Some BIOSes change the (translated) geometry if you change from Normal or Large to LBA. The same thing may happen if you transfer a disk that has been formatted on an old, non-LBA computer to a new one that uses LBA. This has destroyed data. Don't let it happen to you.
Section 10 tells more about the differences between these three.
Unfortunately, no. Proceed with care.
While with many BIOSes, the sectors on the disk are addressed in the same order independent of the translation mode, a few use a different type of translation algorithm. The latter type of BIOS will shuffle your data as if it were a deck of cards if you alter the translation mode.
Moreover, BIOSes that conform to the WD Guide may use completely dissimilar drive geometries in the software (int13) interface depending on the translation mode. If this happens it will wreak havoc with your data. This represents a major flaw in the WD EBIOS specification.
In both of these cases, after changing the translation mode, you must repartition and reformat your disk.
The only reason why you would want to enable this option is that DMA modes are less likely to corrupt data than PIO modes. There will be no difference in CPU usage. (when DMA/33 arrives, the improved bandwidth will be another reason).
Unfortunately, at least one user has reported a drastic decline in drive throughput with DMA enabled. The reasons are unclear, so YMMV.
FDISK
sees only 504MB of my disk! First and foremost, do you have an Enhanced BIOS? See section 2.8 and Q 1 for more details. If you do have an EBIOS, make sure you have enabled translation: usually, either 'Large' or 'LBA'. If you see no such options in your BIOS setup, remember that some types of BIOS offer them only when you tell it to autodetect the drives.
Last but not least, remove all old partitions before trying to create new ones after changing the translation mode.
FDISK
will partition only 2GB. There's nothing wrong; this is a limitation of the DOS FAT and Win95 VFAT filesystems. You will have to create multiple partitions in order to use the full drive size.
This limitation has been addressed in Microsoft's new FAT32 filesystem, currently only available in the Win95 OEM 2 release. It allows giant multi-gigabyte partitions. At the time of writing this release can be sold with new hardware only and is unavailable to ordinary mortals.
Some try to work around the 504MB / 1024 cylinders issue by making a large
partition using a friend's computer, Linux' fdisk
, or something
else. They use it for a day or two, conclude that it works, then post a
triumphant article claiming that they found the Solution To Everyone's
Problems[TM].
It will work... for precisely 1024 cylinders. The very moment the OS or anything else attempts to write something to cylinder 1025 through int13 calls, the write wraps around to cylinder 0. This cylinder happens to hold some of the most important data structures on the disk: the Master Boot Record, partition table, both FAT copies and the root directory of the first partition. Overwrite these and probably only a specialized data recovery company will be able to salvage your data.
Try it if you must. If you know exactly what you're doing, you can make it work using Win95. Sort of. The first error will be fatal. But please don't post any stories about it, recommending the procedure to everyone. The spectres of their valuable data will come back to haunt you.
This is a convenient option, but there are caveats.
The software, sometimes bearing an exotic name depending on the licensee, is usually a version of either MicroHouse's EZ-Drive or OnTrack's Disk Manager. Disk Manager, when used on the boot drive, has to resort to some trickery in order to be loaded very early during the boot process (which is necessary for technical reasons). This is accomplished by modifying the Master Boot Record (MBR), the first piece of code the BIOS loads and executes when the computer boots, and storing a Dynamic Drive Overlay (DDO) on the very first disk track. EZ-Drive works in a similar fashion.
An annoying side effect of using a software solution is that operating system installations, which often overwrite the MBR, will render the contents of your harddisk inaccessible. You will need to restore the MBR from the installation floppy to regain access to your partitions.
Moreover, such software tends to create partitions quite different from 'standard' translation schemes as used by most Enhanced BIOSes. Many device drivers dealing with the disk will fail even if they work fine with other schemes. Important examples are (E)IDE interface drivers; remember that without these drivers an interface will in general be much slower. You'll need drivers that are specifically aware of the translation software you use. Also, many operating systems other than DOS will not be able to access or use the drive, at least not 'out of the box'. Disk fixing utilities may fail to work if the partition table or the overlay is damaged.
This also makes it difficult to upgrade to a BIOS based solution. OnTrack Disk Manager version 7 includes a migration utility for the purpose and improves on version 6 in a number of other ways. It allows multiple operating systems and is compatible with most interfaces and drivers, including those for ATAPI CD-ROMs. Owners of version 6.03, which is still often included with hard drives, can download an update patch from OnTrack http://www.ontrack.com/pub/software/dmpatch.zip that gives some of the benefits of version 7. View http://www.ontrack.com/dm.html for general information.
For older versions of Disk Manager, IBM and Microsoft have fixes for OS/2 (in FixPak 5 or later, or out of the box in Warp FullPack and Warp Connect) and NT (Service Pack 2). Win95 should support Disk Manager and EZDrive out of the box (see Microsoft KnowledgeBase article Q126855, "Windows 95 Support for Large IDE Hard Disks"). More about Disk Manager in section 13.1 .
If you have a Disk Manager or EZDrive partition and are upgrading to a translating BIOS, you have three options.
This software is usually installed in the boot drive's Master Boot Record (MBR). Normal repartitioning and reformatting of the drive usually does not refresh the MBR, which can make for a frustrating experience. Fortunately, it's not very hard once you know how.
The best way to deinstall is to follow the procedure outlined in the utility's
documentation. If this is not available, the following procedure usually works:
boot from a clean floppy with at least DOS, FORMAT.COM
and
FDISK.COM
on it. Then type FDISK /MBR
. This should refresh the
code in your MBR. After that, repartition and reformat as usual.
For reasons I do not understand, some Disk Manager versions are reported to
cling to life rather tenaciously (perhaps due to overambitious virus
protection by the BIOS?). In that case, you need DM.EXE
. Type DM
/Y-
. If that fails as well, the following procedure was reported to
work by Mark Brown (
mrkbrown@netcom.com
).
DM
(in this case, v.6.03)If you have faced similar situations and can add to this, please share your knowledge. A good candidate would be a utility that simply zaps the partition table---any takers?
WARNING. Disk Manager and EZDrive partitions differ from those created by a translating BIOS. Expect your data to be inaccessible after this operation. An exception is v7.x of OnTrack's Disk Manager; DM.EXE has a Migrate feature that works with many BIOSes.
WARNING. Some controllers and security software stores information on track
0 which FDISK /MBR
will clear. In this case, the data on the disk is
lost anyway, but there are a number of circumstances where this command can
destroy data.
Do not confuse this with Smartdrive (or whatever) lazy writes: what is meant here is altering the drive's buffer cache management algorithm. This is possible using newer versions of Drive Rocket, with hdparm under Linux, and probably other utilities too. Provided, of course, the drive supports this feature. Sometimes it can also be done using jumpers on the drive.
There seem to be problems with this, if a program will issue a soft-reset (which on Intel Pentium Motherboards also issues a hardware-reset) as soon as it sees the last IRQ, which overall ends up corrupting data. Use with care, and backup.
MS-DOS assigns drive letters as follows.
a:
and b:
are reserved for floppy drives.c:
, in
order. Normally, you can have just one primary DOS/Windows partition
on every drive.c:
and d:
, adding a second drive with one primary
partition on it will bump the former d:
partition up to
e:
. If you want to avoid this, do not define primary partitions
on all drives except the first one.CONFIG.SYS
and
AUTOEXEC.BAT
files. Some devices such as CD-ROMs have no BIOS
support and get their drive letters only here.Next Chapter, Previous Chapter
Table of contents of this chapter, General table of contents
Top of the document, Beginning of this Chapter