Message-ID:	<3F1DF2C0.CEE3217E@worldnet.att.net>
From:	Paul Cousoulis <paulcsouls AT worldnet DOT att DOT net>
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: New to djgpp. Questions about protected mode, etc.
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Date:	Wed, 23 Jul 2003 02:28:41 GMT
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Hi Teece,

I just did a similiar project to test some hardware. I ran DJGPP on a
WIN98 platform. The biggest problem is setting a DMA buffer. The XMS
does not work in WIN98. I had to write a VDS driver to create a buffer
and the buffer size is extremely limited. If you use DOS you don't have
these problems. I stuck with WIN98 because, I like using TextPad to edit
my code, rebooting in dos is time consuming and my real purpose was to
test an FPGA. 

Paul

> Teece wrote:
> 
> Please bear with me since I am not all that sure about how to ask the
> questions that I have.
> 
> I have an application that I want to develop for the PC with special
> hardware that will run on the PCI bus. I will need to send data from
> the program directly to the hardware. It is not necessary that I use a
> sophisticated operating system like XP or even any version of Windows.
> Therefore I can avoid the difficulty of writing Windows device drivers
> for the new hardware, etc.
> 
> I suppose that I could go a couple of ways. One way would be to use
> good old DOS, which does not run in protected mode, and use DJGPP (or
> VC1.52, I think) to obtain an executable.  Since DOS does not know
> about protected mode I would not cause a segmentation fault when I
> directly access the PCI hardware. Is this correct?
> 
> I was reading in the DJGPP documentation that DJGPP has a DOS
> extender. This was described as a layer of software that "traps the
> call, switches the CPU to real mode, reissues the call, waits for the
> service to do its thing, then switches the CPU back into protected
> mode, and returns to the application code that called the real-mode
> service".
> 
> Does Windows have a DOS extender? Is it not possible to run old DOS
> programs on XP in what passes for a DOS emulator?
> 
> Does Linux have a DOS extender? Will an executable made with DJGPP run
> on Linux?
> 
> Thank You
> Tom
> tom_cip_11551 AT hotmail DOT com
> 
> 
> 
> 
> 
>

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