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Troubleshooting Performance Tuning

This section describes specific issues in performance and how to correct them. For information about general procedures and Windows 98 tools that can be used for troubleshooting, see Chapter 27, "General Troubleshooting."

Optimize performance of the floppy disk drive.

Some computers, especially portable ones, start Windows with a disk mounted in the floppy drive. If you commonly add or remove floppy disks between Windows sessions and the computer often does not recognize the new disk, use the Search for new floppy disk drives each time your computer starts feature to direct the floppy driver to scan for new disks at every startup.

If this feature is not selected, Windows starts faster, because a floppy driver uses the previous settings for drive information.

To optimize performance of the floppy disk drives

  1. In Control Panel, double-click System, and then click the Performance tab.
  2. Click File System, and then click the Floppy Disk tab.
  3. Select the Search for new floppy disk drives each time your computer starts check box to scan for new drives every time Windows starts

    – Or –

    Clear the check box so Windows will not scan for new drives at startup.

The DMA check box in Device Manager will not remain checked.

When you enable DMA support on the Settings tab in the properties for an IDE hard disk, the DMA check box in Device Manager may not remain checked even though the IDE controller supports bus mastering and DMA. This happens because the hard disk may not support a multiple-word DMA protocol.

DMA (also referred to as bus mastering) reduces CPU overhead by providing a mechanism for data transfers that do not require monitoring by the CPU. The transfer rate for a particular data transfer event will not noticeably increase. However, overall CPU overhead should be reduced using DMA mode.

A disadvantage of implementing DMA data transfer operations is that the PC/AT and IDE hard disk controller evolved around PIO data transfer methods. As a result, the system Int 13h BIOS and native operating system device drivers evolved around PIO transfers instead of DMA transfers. Modifications to the BIOS, as well as external device drivers, have been necessary to achieve the incremental performance that DMA offers.

To determine whether your IDE hard disk supports multiple-word DMA protocol, test the primary IDE drive and the secondary IDE drive.

To test the primary IDE drive

  1. Restart the computer. Press the CTRL key to get the Windows 98 Startup menu, and then choose Command Prompt Only.
  2. At the command prompt, type debug.
  3. At the hyphen prompt, type the following lines, pressing ENTER after each line. Do not type the comment.

    Note

    The first character of each line is the letter o, not the numeral zero.

Type Comment
o 1f6 a0 a0 (a-zero) is for a master drive; use b0 for a slave.
o 1f2 22 22 is for DMA mode 2; use 21 for DMA mode 1.
o 1f1 03 03 (zero-3) is to program the hard disk timing.
o 1f7 ef ef is the set feature command for the hard disk.
i 1f1 Reads in the error status; a value is returned.

If the number returned after entering i 1f1 is 00, the hard disk accepts the DMA protocol timing that you entered with the o 1f2 statement, and the hard disk supports DMA. A return value of 04 indicates that the hard disk does not support a DMA multiple-word protocol. If the value returned is not 00 or 04, you may not have typed the characters correctly, or you may need to quit Windows.

PIO mode 3 hard disks may support multiple-word DMA mode 1. PIO mode 4 hard disks should support multiple-word DMA mode 2. If you have a PIO mode 4 drive that does not support multiple-word DMA mode 2, it is possible that the hard disk has a firmware problem. Contact the hard disk manufacturer, and verify the firmware version.

  1. To quit Debug, type q and press ENTER.

To test the secondary IDE drive

  1. Restart the computer. Press CTRL to get the Windows 98 Startup menu, and then choose Command Prompt Only.
  2. At the command prompt, type debug.
  3. At the hyphen prompt, type the following lines, pressing ENTER after each line. Do not type the comment.

    Note

    The first character of each line is the letter o, not the numeral zero.

Type Comment
o 176 a0 a0 (a-zero) is for a master drive; use b0 for a slave.
o 172 22 22 is for DMA mode 2; use 21 for DMA mode 1.
o 171 03 03 (zero-3) is to program the hard disk timing.
o 177 ef ef is the set feature command for the hard disk.
i 171 Reads in the error status; a value is returned.

If the number returned after entering i 171 is 00, the hard disk accepts the DMA protocol timing that you entered with the o 172 statement, and the hard disk supports DMA. A return value of 04 indicates that the hard disk does not support a DMA multiple-word protocol.

If your drive does support a DMA multiple-word protocol and the DMA check box will not remain enabled, the IDE controller may not be compatible with the Microsoft IDE bus mastering driver.

  1. To quit Debug, type q and press ENTER.
Additional Resources
For more information about See this resource
MS-DOS memory settings Microsoft MS-DOS 6.2x Technical Reference or other books on MS-DOS memory management
Creating drivers Microsoft Windows 98 Device Development Kit
Resource kit tools Microsoft Windows 98 Resource Kit Tools Help on the Windows 98 compact disc