Perplexing Problems with Your Newly Installed Hard Drive?

By Bill Poynter for TechRepublic

Have you just installed a new large hard drive in your computer and installed the operating system with no hitches, only to discover that Microsoft® Windows® 98 or Microsoft Windows 95 SR2 won't run in Normal Mode?

If Windows is starting okay in Safe Mode but all attempts to start in Normal Mode result in hang-ups, spontaneous shutdowns, or reboots, I may have the answer for you. Even if you haven't experienced any problems so far, there may be a hard drive upgrade looming in your future.

What Is an Ultra DMA/66 Interface?

A little history lesson is appropriate in a discussion concerning fast integrated device electronics (IDE) interfaces. With each generation of hard drives growing progressively faster, improving the performance of the interface between the hard drive and the computer has become more critical.

Direct memory access (DMA) Modes classify the transfer rates and speeds of IDE hard drives. Standard DMA Modes fall in the range of 1 to 4. As you can guess, higher numbers mean faster speeds. Transfer rates for the different DMA Modes include:

DMA Mode 1: 4 MBps

DMA Mode 2: 8 MBps

DMA Mode 3: 16 MBps

DMA Mode 4: 24 MBps

As fast as IDE drives were becoming, they still lagged behind their small computer systems interface (SCSI) cousins. To overcome this, the industry created the Ultra DMA standard. Ultra DMA/33 came to market in 1997 and increased the transfer rate to 33.3 MBps. Most people referred to this implementation as Ultra DMA.

Now the new kid is on the block. Called Ultra DMA/66, it supports a 66.6 MBps rate. Each succeeding generation of the DMA interface has doubled the speed of its predecessor. Will we have DMA/132 next year?

So What's the Problem?

As long as all the components in your machine come from the same generation, you won't have any problems. But that's not always the case. For instance, I learned all about Ultra DMA/66 the same way that I learn most things—the hard way.

The machine that I am typing this on is a one-year-old Pentium 233 with a 2 GB hard drive. When it came time to install a larger drive, I found an 8 GB drive at the right price, so I proceeded with installing it. I am accustomed to replacing a hard drive and transferring its data quickly and easily with the drive-cloning software available today.

I planned to use one of the many drive copy programs that I had accumulated over the last couple of years. I was going to quickly clone the image of my old drive onto the new one and be done with it. Well, things didn't go quite as planned.

The cloning part worked fine, but when I set up the new drive as drive C, Windows would start to load and then would either hang, shut down, or produce error messages about not being able to find needed files. However, the machine would boot to the C: prompt just fine. It would also allow Windows to start up in Safe Mode. Even though Microsoft Windows reported that it was missing some files it needed to start up, all the directories and files were still there and accessible.

Because the only hardware I had changed was the hard drive, it didn't seem that any of the normal Windows driver problems would be the hang-up. My first impulse was to copy the drive again, using different cloning software. This action produced the same result.

Next, I tried a clean install of Windows 98 on the drive. I first ran Fdisk to ensure there would be no vestiges of a botched installation.

Guess what? Same results! Windows just wouldn't run! Not being one to give up too quickly, I picked up another drive of the same make and model and gave it a try. That produced the same results.

Next I updated the Flash BIOS on the motherboard, but that didn't help a bit. Now it was time to visit the Web site of the drive manufacturer to see what utilities were available to test my drive. The drive was a Western Digital and it tested perfectly.

I decided to once again initialize the drive, only this time I would use software that I downloaded from Western Digital's site. It was during this formatting procedure that a message flashed on the screen indicating the possibility of the native DMA mode of my new drive not being compatible with my old hardware.

I nearly ignored this message, thinking it didn't concern me since I knew that both my motherboard and operating system (Windows 98) supported Ultra DMA.

What the message really told me was that this drive uses a new version of the Ultra DMA interface called Ultra DMA/66. My motherboard with the integrated IDE interface only supports the Ultra DMA/33 version.

When I was writing to the drive, during both the cloning and the clean install, there were no problems, because the data rate was determined by the BIOS of the motherboard, not by the new drive. The problem arose when I tried to read from the drive while starting Windows. The interface supplied data at up to 66.6 MBps only when Microsoft Windows tried to implement the DMA transfer mode.

Microsoft Windows couldn't detect the difference between DMA/33 and DMA/66. In spite of the fact that the rest of my hardware could operate only at 33.3 MBps, Microsoft Windows allowed the drive to try to operate in DMA/66 mode—hence, the errors.

Why Was Microsoft Windows Able to Run in Safe Mode?

When you start Microsoft Windows in Safe Mode, the DMA driver doesn't load. The problem occurs only when Microsoft Windows starts in Normal Mode and tries to load the DMA driver. When that happens, everything goes haywire.

Knowing this, you might think that all you need to do is to start Microsoft Windows in Safe Mode and turn off the Microsoft Windows DMA Mode support for this drive. Unfortunately, when you're running in Safe Mode, you can't access that option to turn it off. The DMA option is available to you only in Normal Mode.

The Temporary Solution

The solution is to go to the page in the Complimentary Metal Oxide Semiconductor (CMOS) Setup that sets the operating parameters for your hard drive and temporarily disables the DMA mode. You can then run Microsoft Windows in Normal Mode and everything will operate normally, although disk performance will be severely reduced.

After starting Microsoft Windows in the Normal Mode, first click the Start button, then select Settings, and Control Panel. Double-click the System icon and, in the System Properties dialog box, select the Device Manager tab. Click the plus sign next to the disk drive icon and then double-click the icon for your hard drive. Next, click the Settings tab and deselect the DMA check box in the Options panel. Click OK twice, and the CMOS DMA setting will no longer have any detrimental effect on Microsoft Windows.

Here's the Best Interim Fix

Western Digital, the manufacturer of the drive that I am using, bundles a utility with its EZ Drive software that allows you to toggle the drive between DMA/33 and DMA/66. By resetting my drive to be compatible with the older DMA/33 standard, I was able to reactivate the DMA mode for the drive in both the CMOS Setup and Microsoft Windows. Visit the Web site of your drive manufacturer to see if it offers such a utility.

My new drive now has a transfer speed at least equal to the drive it replaced. I don't find that a very fulfilling solution since I just shelled out the bucks for a larger, faster drive and all I ended up with is larger. If I want to take advantage of the higher transfer speed capability of my new drive, some hardware upgrades will be needed.

Upgrade Your Problems Away

Probably the easiest upgrade is to disable the on-board IDE controller and install an Ultra DME/66-compatible controller card. To me, this is not a very appealing solution. The price of a new Ultra DMA/66 controller card will probably be very close to the price of a new motherboard.

There may be occasions when you have a compelling reason for staying with your present motherboard, but usually replacing it with one having BIOS and chipset support for Ultra DMA/66 is the most logical solution. Doing this will provide you with an upgrade path to other new enhancements that were unavailable with your old motherboard.

Whichever way you go to gain the Ultra DMA/66 capability, you will have to acquire a new data cable to connect the drive. The Ultra DMA/66 protocol requires a different cable design with twice the number of conductors. It has connectors that are compatible with the existing 40-pin headers on IDE drives and controllers, but the ribbon cable contains 80 conductors instead of 40. The extra 40 conductors are all ground lines placed there to provide additional shielding and protection against cross-talk between the conductors. This cross-talk is likely due to the higher data rate capability of the new interface.

The DMA/66 hard drive supposedly has the ability to sense the presence of this cable and it won't implement Ultra DMA/66 unless the 80-conductor cable is attached. Evidently, in my case the drive tried to implement Ultra DMA/66 anyway.

Conclusion

Before installing a new hard drive, find out which transfer protocol it uses. If the new drive uses Ultra DMA/66 and your present IDE controller doesn't support it, see if the drive manufacturer has provided a method of reverting to DMA/33. If not, you may have to turn off DMA support completely and suffer a large performance hit.

Bill Poynter began working with computers in 1979 with one of the first personal computers on the market: a TI-99/4A manufactured by Texas Instruments. In addition to his experience in the two-way radio communications industry as an account representative, he's been involved in the hardware side of the computer industry, including the sale, repair, troubleshooting, and upgrading of both home computers and office networked machines. You can reach Bill at billpoynter@ntr.net .