Tag Archives: Windows NT 4.0

32-bit Transfer Mode - BIOS Optimization Guide

32-bit Transfer Mode – The BIOS Optimization Guide

32-bit Transfer Mode - BIOS Optimization Guide

32-bit Transfer Mode

Common Options : On, Off

 

Quick Review

This BIOS feature allows you to command the IDE controller to combine two 16-bit hard disk reads into a single 32-bit data transfer to the processor. This greatly improves the performance of the IDE controller as well as the PCI bus.

Therefore, it is highly advisable to enable 32-bit Transfer Mode. If you disable it, data transfers from the IDE controller to the processor will only occur in 16-bits chunks.

 

Details

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This BIOS feature is similar to the 32-bit Disk Access BIOS feature. The name 32-bit Transfer Mode is actually a misnomer because it doesn’t really allow 32-bit transfers on the IDE bus.

The IDE interface is always 16-bits in width even when the IDE controller is on the 32-bit PCI bus. What this feature actually does is command the IDE controller to combine two 16-bit reads from the hard disk into a single 32-bit double word transfer to the processor. This allows the PCI bus to be more efficiently used as the number of transactions required for a particular amount of data is effectively halved!

However, according to a Microsoft article (Enhanced IDE operation under Windows NT 4.0), 32-bit disk access can cause data corruption under Windows NT in some cases. Therefore, Microsoft recommends that Windows NT 4.0 users disable 32-bit Disk Access.

Lord Mike asked ‘someone in the know’ about this matter and he was told that the data corruption issue was taken very seriously at Microsoft and that it had been corrected through the Windows NT 4.0 Service Pack 2. Although he couldn’t get an official statement from Microsoft, it’s probably safe enough to enable 32-bit Disk Access on a Windows NT 4.0 system, just as long as it has been upgraded with Service Pack 2.

Because it realizes the performance potential of the 32-bit IDE controller and improves the efficiency of the PCI bus, it is highly advisable to enable 32-bit Transfer Mode.

If you disable it, data transfers from the IDE controller to the processor will only occur in 16-bits chunks. This degrades the performance of the IDE controller as well as the PCI bus.

As such, you should disable this feature only if you actually face the possibility of data corruption (with an unpatched version of Windows NT 4.0).

You can also find more information on the Windows NT issue in the details of the IDE HDD Block Mode feature!

 

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IDE HDD Block Mode – The BIOS Optimization Guide

IDE HDD Block Mode

Common Options : Enabled, Disabled

 

Quick Review

The IDE HDD Block Mode BIOS feature speeds up hard disk drive access by transferring multiple sectors of data per interrupt instead of using the usual single-sector transfer mode. This mode of transferring data is known as block transfers.

When you enable this feature, the BIOS will automatically detect if your hard disk drive supports block transfers and set the proper block transfer settings for it. Depending on the IDE controller, up to 64 KB of data can be transferred per interrupt when block transfers are enabled. Since all current hard disk drives support block transfers, there is usually no reason why IDE HDD Block Mode should be disabled.

Please note that if you disable IDE HDD Block Mode, only 512 bytes of data can transferred per interrupt. Needless to say, this will significantly degrade performance.

Therefore, you should disable IDE HDD Block Mode only if you actually face the possibility of data corruption (with an unpatched version of Windows NT 4.0). Otherwise, it is highly recommended that you enable this BIOS feature for significantly better hard disk drive performance!

 

Details

The IDE HDD Block Mode BIOS feature speeds up hard disk drive access by transferring multiple sectors of data per interrupt instead of using the usual single-sector transfer mode. This mode of transferring data is known as block transfers.

When you enable this feature, the BIOS will automatically detect if your hard disk drive supports block transfers and set the proper block transfer settings for it. Depending on the IDE controller, up to 64 KB of data can be transferred per interrupt when block transfers are enabled. Since all current hard disk drives support block transfers, there is usually no reason why IDE HDD Block Mode should be disabled.

However, if you are running on Windows NT 4.0, you might need to disable this BIOS feature because Windows NT 4.0 has a problem with block transfers. According to Chris Bope, Windows NT does not support IDE HDD Block Mode and enabling this feature can cause data to be corrupted.

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Ryu Connor confirmed this by sending me a link to a Microsoft article (Enhanced IDE operation under Windows NT 4.0). According to this article, IDE HDD Block Mode and 32-bit Disk Access have been found to cause data corruption in some cases. Therefore, Microsoft recommends that Windows NT 4.0 users disable IDE HDD Block Mode.

Lord Mike asked ‘someone in the know‘ about this matter and he was told that the data corruption issue was taken very seriously at Microsoft and that it had been corrected through the Windows NT 4.0 Service Pack 2. Although he could not get an official statement from Microsoft, it is probably safe enough to enable IDE HDD Block Mode on a Windows NT 4.0 system, just as long as it has been upgraded with Service Pack 2.

Please note that if you disable IDE HDD Block Mode, only 512 bytes of data can transferred per interrupt. Needless to say, this will significantly degrade performance.

Therefore, you should disable IDE HDD Block Mode only if you actually face the possibility of data corruption (with an unpatched version of Windows NT 4.0). Otherwise, it is highly recommended that you enable this BIOS feature for significantly better hard disk drive performance!

 

Support Tech ARP!

If you like our work, you can help support our work by visiting our sponsors, participate in the Tech ARP Forums, or even donate to our fund. Any help you can render is greatly appreciated!