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phoenix |
Some notes for ftape users with PCI motherboards:
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=================================================
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The problem:
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There have been some problem reports from people using PCI-bus based
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systems getting overrun errors.
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I wasn't able to reproduce these until I ran ftape on a Intel Plato
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(Premiere PCI II) motherboard with bios version 1.00.08AX1.
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It turned out that if GAT (Guaranteed Access Timing) is enabled (?)
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ftape gets a lot of overrun errors.
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The problem disappears when disabling GAT in the bios.
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Note that Intel removed this setting (permanently disabled) from the
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1.00.10AX1 bios !
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It looks like that if GAT is enabled there are often large periods
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(greater than 120 us !??) on the ISA bus that the DMA controller cannot
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service the floppy disk controller.
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I cannot imagine this being acceptable in a decent PCI implementation.
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Maybe this is a `feature' of the chipset. I can only speculate why
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Intel choose to remove the option from the latest Bios...
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The lesson of this all is that there may be other motherboard
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implementations having the same of similar problems.
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If you experience a lot of overrun errors during a backup to tape,
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see if there is some setting in the Bios that may influence the
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bus timing.
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I judge this a hardware problem and not a limitation of ftape ;-)
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My DOS backup software seems to be suffering from the same problems
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and even refuses to run at 1 Mbps !
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Ftape will reduce the data-rate from 1 Mbps to 500 Kbps if the number
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of overrun errors on a track exceeds a threshold.
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Possible solutions:
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Some of the problems were solved by upgrading the (flash) bios.
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Other suggest that it has to do with the FDC being on the PCI
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bus, but that is not the case with the Intel Premiere II boards.
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[If upgrading the bios doesn't solve the problem you could try
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a floppy disk controller on the isa-bus].
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Here is a list of systems and recommended BIOS settings:
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Intel Premiere PCI (Revenge):
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Bios version 1.00.09.AF2 is reported to work.
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Intel Premiere PCI II (Plato):
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Bios version 1.00.10.AX1 and version 11 beta are ok.
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If using version 1.00.08.AX1, GAT must be disabled !
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ASUS PCI/I-SP3G:
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Preferred settings: ISA-GAT-mode : disabled
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DMA-linebuffer-mode : standard
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ISA-masterbuffer-mode : standard
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DELL Dimension XPS P90
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Bios version A2 is reported to be broken, while bios version A5 works.
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You can get a flash bios upgrade from http://www.dell.com
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To see if you're having the GAT problem, try making a backup
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under DOS. If it's very slow and often repositions you're
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probably having this problem.
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--//--
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LocalWords: ftape PCI bios GAT ISA DMA chipset Mbps Kbps FDC isa AF ok ASUS
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LocalWords: SP linebuffer masterbuffer XPS http www com
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