dma crosses 64k boundary error

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dma crosses 64k boundary error

Dimitris Zilaskos
Hi,

I keep getting the error dma crosses 64k boundary when using tools like rawrite3 or hard drive manufacturers tools floppy creation software. I need to boot from Windows 98 bootdisk to get rid of it.

Please let me know if there is a way to get rid of this problem under FreeDOS.

Cheers,

Dimitris



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Re: dma crosses 64k boundary error

Eric Auer-3

> I keep getting the error dma crosses 64k boundary when using tools like
> rawrite3 or hard drive manufacturers tools floppy creation software. I need
> to boot from Windows 98 bootdisk to get rid of it.

Maybe your BIOS or MBR-based dynamic drive overlay / EZ-drive is
less flexible with DMA boundaries than the BIOS itself was? Some
tools like LOWDMA might help to avoid boundary issues as positive
side effect of enforcing DMA outside UMB... Still, all educated
guesses, I do not know enough about why and when you started to
see those DMA boundary errors... I would expect RAWRITE3 itself
to actively avoid offending buffer locations. If that is the case
then DOS would be to blame by internally using badly located I/O
buffers. If it is not the case, then RAWRITE3 would be to blame:
Changes in symptoms could then be caused by changes in general
DOS RAM layout, for example different drivers being loaded...

Eric



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Re: dma crosses 64k boundary error

tom ehlert
In reply to this post by Dimitris Zilaskos
> I keep getting the error dma crosses 64k boundary when using tools
> like rawrite3 or hard drive manufacturers tools floppy creation
> software. I need to boot from Windows 98 bootdisk to get rid of it.

> Please let me know if there is a way to get rid of this problem under FreeDOS.

MSDOS redirects int 13 to an internal driver, detects DMA access crossing a 64k boundary,
and avoids it.

FreeDOS ddoes not do this; sorry.

there was no need to do this so far; IMO rawrite3 could/should handle
this by itself. of course, software is usually only tested against
MSDOS, so there is little motivation to do so for rawrite3
programmers.

I'm still surprised this comes up today, and not 15 years ago.
do you have remarkable hardware?

Tom


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Re: dma crosses 64k boundary error

Dimitris Zilaskos
Hi,

Hi,

Thank you for your reply. Hardware is a year 1995 486-DX4 100, hardly remarkable at its time.

Cheers,

Dimitris


On Tue, Aug 23, 2016 at 6:28 PM, Tom Ehlert <[hidden email]> wrote:
> I keep getting the error dma crosses 64k boundary when using tools
> like rawrite3 or hard drive manufacturers tools floppy creation
> software. I need to boot from Windows 98 bootdisk to get rid of it.

> Please let me know if there is a way to get rid of this problem under FreeDOS.

MSDOS redirects int 13 to an internal driver, detects DMA access crossing a 64k boundary,
and avoids it.

FreeDOS ddoes not do this; sorry.

there was no need to do this so far; IMO rawrite3 could/should handle
this by itself. of course, software is usually only tested against
MSDOS, so there is little motivation to do so for rawrite3
programmers.

I'm still surprised this comes up today, and not 15 years ago.
do you have remarkable hardware?

Tom


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Re: dma crosses 64k boundary error

Rugxulo
In reply to this post by tom ehlert
Hi,

On Tue, Aug 23, 2016 at 12:28 PM, Tom Ehlert <[hidden email]> wrote:
>>
>> I keep getting the error dma crosses 64k boundary when using tools
>> like rawrite3 or hard drive manufacturers tools floppy creation
>> software. I need to boot from Windows 98 bootdisk to get rid of it.
>
> I'm still surprised this comes up today, and not 15 years ago.
> do you have remarkable hardware?

Is it possible that different tools don't exhibit the same behavior / bug?

So, just for comparison, there are various other tools to write floppy
images to physical disk:

1). FD diskcopy
http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/dos/diskcopy/0.9/

2). sfx14436 (stub)
https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/tools/

3). FreeBSD fdimage.exe
http://ftp-archive.freebsd.org/pub/FreeBSD-Archive/old-releases/i386/4.8-RELEASE/4.8-RELEASE/tools/

4). PLoP's diskimg
https://www.plop.at/en/dostools.html#diskimg.com

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Re: dma crosses 64k boundary error

Dimitris Zilaskos
Hi,

rawrite1 also works. Problem is tools from maxtor/western digital/seagate etc appear to be based around some hard wired version of rawrite3, which prevents these tools from being able to create their bootdisks under freedos.

Cheers,

Dimitris

On Tue, Aug 23, 2016 at 9:35 PM, Rugxulo <[hidden email]> wrote:
Hi,

On Tue, Aug 23, 2016 at 12:28 PM, Tom Ehlert <[hidden email]> wrote:
>>
>> I keep getting the error dma crosses 64k boundary when using tools
>> like rawrite3 or hard drive manufacturers tools floppy creation
>> software. I need to boot from Windows 98 bootdisk to get rid of it.
>
> I'm still surprised this comes up today, and not 15 years ago.
> do you have remarkable hardware?

Is it possible that different tools don't exhibit the same behavior / bug?

So, just for comparison, there are various other tools to write floppy
images to physical disk:

1). FD diskcopy
http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/dos/diskcopy/0.9/

2). sfx14436 (stub)
https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/tools/

3). FreeBSD fdimage.exe
http://ftp-archive.freebsd.org/pub/FreeBSD-Archive/old-releases/i386/4.8-RELEASE/4.8-RELEASE/tools/

4). PLoP's diskimg
https://www.plop.at/en/dostools.html#diskimg.com

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Re: dma crosses 64k boundary error

Dimitris Zilaskos
Hi,

Based on Eric's comments and with Jack's help, I was able to get rawrite3 to work under freedos by a) loading lowdma.sys in fdconfig.sys early durting boot b) LH rawrite3.

Unfortunately that does not work with hard drive manufacturer's tools, they complain at LH about lack of RAM. Since they are executables around 1.44 MB I suspect they are just too big for LH to work with them.

Cheers,

Dimitris


On Tue, Aug 23, 2016 at 10:56 PM, Dimitris Zilaskos <[hidden email]> wrote:
Hi,

rawrite1 also works. Problem is tools from maxtor/western digital/seagate etc appear to be based around some hard wired version of rawrite3, which prevents these tools from being able to create their bootdisks under freedos.

Cheers,

Dimitris

On Tue, Aug 23, 2016 at 9:35 PM, Rugxulo <[hidden email]> wrote:
Hi,

On Tue, Aug 23, 2016 at 12:28 PM, Tom Ehlert <[hidden email]> wrote:
>>
>> I keep getting the error dma crosses 64k boundary when using tools
>> like rawrite3 or hard drive manufacturers tools floppy creation
>> software. I need to boot from Windows 98 bootdisk to get rid of it.
>
> I'm still surprised this comes up today, and not 15 years ago.
> do you have remarkable hardware?

Is it possible that different tools don't exhibit the same behavior / bug?

So, just for comparison, there are various other tools to write floppy
images to physical disk:

1). FD diskcopy
http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/dos/diskcopy/0.9/

2). sfx14436 (stub)
https://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/tools/

3). FreeBSD fdimage.exe
http://ftp-archive.freebsd.org/pub/FreeBSD-Archive/old-releases/i386/4.8-RELEASE/4.8-RELEASE/tools/

4). PLoP's diskimg
https://www.plop.at/en/dostools.html#diskimg.com

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Re: dma crosses 64k boundary error

Eric Auer-3

Hi Dimitris,

> Based on Eric's comments and with Jack's help, I was able to get rawrite3
> to work under freedos by a) loading lowdma.sys in fdconfig.sys early
> during boot b) LH rawrite3.

You probably mean the LOWDMA sys and com which come with UMBPCI. In that
case, you can patch 80FCA05B into 80F0105B to trap not only I/O buffers
in UMB or HMA but all buffers. Will make things slow but still useful as
you will not need to use LH that way. Your disk image writing tools are
probably 1.44 MB in size because they embed the whole floppy image, but
they do not have to have 1.44 MB free DOS memory, luckily ;-) Note that
LOWDMA only traps CHS I/O and not LBA I/O, but LBA is rarely used by a
floppy image writer anyway.

Cheers, Eric

PS: Lowdma also comes with source code, so if you have the Assembler,
you can of course also patch the source (comparison to 0xA0, not the
one while loading but the one in the int handler) if you prefer that.



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