Notes

How to Perform a Drive Test:

The DiskDupe drive test feature is an excellent method for diagnosing a setup problem.

Run DiskDupe and go to Setup|Drives menu, highlight the drive with the DMA problem, and type "T" for test.

How to Change the Bus Speed:

Sometimes the bus speed of the computer may be too slow for the fast DMA rates that DiskDupe uses. Most people do not realize that the bus speed of the computer does not depend on the processor speed. A 166Mhz Pentium can still have a slow bus speed.
1. Reset or turn off/on your computer. While the computer is booting look for instructions on entering your computer's CMOS (for most computer's pressing the [DEL] key will take you to a CMOS menu, on others it is the [F1] key).

2. From the CMOS menu, select either Advanced Chipset Setup or Chipset Setup (the terms will vary depending on the BIOS manufacturer).

3. From the Advanced Chipset Setup or Chipset Setup menu, look for options like: Bus Speed, Bus Wait States, DMA speed or I/O Recovery Time that can be changed. Change one option at a time trying all the possible combinations available, even values that might slow the bus speed down. Depending on the item being changed, its value may be expressed as a "CLCK/X" (Clock divided by X) expression. The higher the "X" value the slower the speed, and the lower the "X" value the higher the speed. Continue this process until you have exhausted all methods for altering the bus speed.

How to Change the DMA Channel:

A DMA conflict can occur when there is a conflict between the floppy controller and some other device in the computer that is using DMA. One solution is to try changing the DMA channel that your floppy drive controller is using
• If you have an Allegro I SDS controller card you can jumper the card to use DMA channel 1, 2, or 3.

• If you have an Allegro II card, the DMA channels can be chosen from within DiskDupe under the Setup|Controllers menu and can be changed to 0, 1, 2, or 3. Remember if you have an SDS drive, you will have to select two different DMA channels.

How to Perform a Clean Boot:

A clean boot is an excellent method for determining whether a device driver or TSR is causing a problem, since the computer is booting without them loading.

To perform a clean boot with Dos 6.0 or later:

Reset or turn off/on your computer. While the computer is booting, press the [F5] key when the computer says "Starting MS-Dos".

To perform a clean boot with Dos 5.0 or earlier:

1. Make a bootable floppy disk first by formatting a disk with the "FORMAT A: /S" from the Dos prompt.

2. Insert the bootable floppy into your drive a: and reset or restart your computer. Your computer will now boot from the floppy disk instead of your hard disk.

DMA Chipset Incompatibility

We have observed that with certain computers that the DMA controller, which handles DMA transfers and DMA requests, will sometimes send an additional byte of data during a block transfer. This additional byte means that the data in memory will not compare to the original data, which produces an error.

If you have tried everything, and you are still experiencing DMA problems, then the DMA chipset that is on the computer's motherboard may not be compatible with the high-speed data transfer that DiskDupe performs. Our recommendation is to try using another computer, preferably a different brand.