From: "Thomas Schachtner" <thomas DOT schachtner AT gmx DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: read a specific memory address
Date: Fri, 4 May 2001 14:20:42 +0200
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

hey, thank you for your info!!!!

Now  I try to use _farpeekb() or the DPMI... functions

Do they work also with WindowsNT/Windows2000 environment?
If not, is there any possibility to read values from a physical address?

Thank your for the help, again

Thomas



"Hans-Bernhard Broeker" <broeker AT physik DOT rwth-aachen DOT de> wrote in message
news:9cp8nj$ap6$1 AT nets3 DOT rz DOT RWTH-Aachen DOT DE...
> Thomas Schachtner <thomas DOT schachtner AT gmx DOT de> wrote:
>
> > I want to read a value that is stored on (Real-Mode-)Address: F000:0000
>
> That's simple. Use the _farpeekb() function.
>
> > And another value from e. g. 0x03847384 (a 32 bit memory address).
>
> There is no such thing as an absolute memory address, from the point
> of view of a DJGPP application. We use a segmented memory model
> similar to the 'tiny' model of 16 bit PC programing times, but with
> segments potentially 4 Gigabytes long.
>
> You're probably referring to a linear adress space (i.e. the actual
> physical address bits at the CPU's pins).  You need special function
> of the __dpmi_*() family to map such addresses into the program's
> memory space, which are not available in all DPMI environments.
>
> > is the address the same as the value from a pointer?
>
> No.
>
> > Why not?
>
> Because of the Memory Management Unit (MMU) built into all x86 CPUs
> since the 386. It translates logical addresses into linear/physical
> ones, based upon settings you make in the 'descriptor tables'.
>
> --
> Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
> Even if all the snow were burnt, ashes would remain.