windows ma taku krasnu vychytavku

PIO mode is enabled by default in the following situations:
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For repeated DMA errors. Windows XP will turn off DMA mode for a device after encountering certain errors during data transfer operations. If more that six DMA transfer timeouts occur, Windows will turn off DMA and use only PIO mode on that device.

In this case, the user cannot turn on DMA for this device. The only option for the user who wants to enable DMA mode is to uninstall and reinstall the device.

Windows XP downgrades the Ultra DMA transfer mode after receiving more than six CRC errors. Whenever possible, the operating system will step down one UDMA mode at a time (from UDMA mode 4 to UDMA mode 3, and so on).
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to sa stalo mne, posledne tri dni som jak debil debugoval ze co tomu notbuku kua je, az kym ma nenapadla vec co ma mala samozrejme napadnut ako prva a to ci nahodou nebezi v PIO mode... a bezal

http://winhlp.com/WxDMA.htm tu je riesenie

ten vbs script som testol, funguje