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how do I read a location in the bios eprom

P: n/a
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)

Nov 14 '05 #1
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P: n/a
just4me <ju*****@nowhere.com> scribbled the following:
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


What was your C question?

--
/-- Joona Palaste (pa*****@cc.helsinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"To doo bee doo bee doo."
- Frank Sinatra
Nov 14 '05 #2

P: n/a
"just4me" <ju*****@nowhere.com> writes:
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


Your question is outside the domain of comp.lang.c, which discusses
only the standard C programming language, including the standard C
library. This is a remarkably narrow topic compared to what many
people expect.

For your convenience, the list below contains topics that are not
on-topic for comp.lang.c, and suggests newsgroups for you to explore
if you have questions about these topics. Please do observe proper
netiquette before posting to any of these newsgroups. In particular,
you should read the group's charter and FAQ, if any (FAQs are
available from www.faqs.org and other sources). If those fail to
answer your question then you should browse through at least two weeks
of recent articles to make sure that your question has not already
been answered.

* OS-specific questions, such as how to clear the screen,
access the network, list the files in a directory, or read
"piped" output from a subprocess. These questions should be
directed to OS-specific newsgroups, such as
comp.os.ms-windows.programmer.misc, comp.unix.programmer, or
comp.os.linux.development.apps.

* Compiler-specific questions, such as installation issues and
locations of header files. Ask about these in
compiler-specific newsgroups, such as gnu.gcc.help or
comp.os.ms-windows.programmer.misc. Questions about writing
compilers are appropriate in comp.compilers.

* Processor-specific questions, such as questions about
assembly and machine code. x86 questions are appropriate in
comp.lang.asm.x86, embedded system processor questions may
be appropriate in comp.arch.embedded.

* ABI-specific questions, such as how to interface assembly
code to C. These questions are both processor- and
OS-specific and should typically be asked in OS-specific
newsgroups.

* Algorithms, except questions about C implementations of
algorithms. "How do I implement algorithm X in C?" is not a
question about a C implementation of an algorithm, it is a
request for source code. Newsgroups comp.programming and
comp.theory may be appropriate.

* Making C interoperate with other languages. C has no
facilities for such interoperation. These questions should
be directed to system- or compiler-specific newsgroups. C++
has features for interoperating with C, so consider
comp.lang.c++ for such questions.

* The C standard, as opposed to standard C. Questions about
the C standard are best asked in comp.std.c.

* C++. Please do not post or cross-post questions about C++
to comp.lang.c. Ask C++ questions in C++ newsgroups, such
as comp.lang.c++ or comp.lang.c++.moderated.

* Test posts. Please test in a newsgroup meant for testing,
such as alt.test.

news.groups.questions is a good place to ask about the appropriate
newsgroup for a given topic.

--
"In My Egotistical Opinion, most people's C programs should be indented six
feet downward and covered with dirt." -- Blair P. Houghton
Nov 14 '05 #3

P: n/a
"just4me" <ju*****@nowhere.com> wrote in message
news:cc***********@news3.infoave.net...
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)

Nov 14 '05 #4

P: n/a
> Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)

There is no way of telling!
<OT>
First of all it depends on wheter or not you have an OS,
ok since you have a bios there is almost certenly an OS involved.
But it could be that you are writing the OS your self. Witch you are not!
Anyway! taken that you have an OS, it is an issue for the given OS.
Almost all OSes are executing user apps in something that is called
protected mode or similar to. (Modern ones at least)
In this mode you are effectivly sheilded from most of the tampering with
stuff like reading BIOS locations.
And even if it would be possible, again it could or could not have multiple
address spaces.
And still there is no telling if it could be read!
So thats why you are being denied help here. You are off-topic.
My guess would be that you are running windows, and if thats the case look
for help at
comp.os.ms-windows
</OT>
//jota
Nov 14 '05 #5

P: n/a
"just4me" <ju*****@nowhere.com> writes:
"just4me" <ju*****@nowhere.com> wrote in message
news:cc***********@news3.infoave.net...
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


Your question is still off-topic. Posting it multiple times
doesn't change that.
Nov 14 '05 #6

P: n/a
> >> Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


Your question is still off-topic. Posting it multiple times
doesn't change that.

As I see it he was quoting his self!
//jota
Nov 14 '05 #7

P: n/a
"just4me" <ju*****@nowhere.com> wrote

Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)

In the olden days you could just declare a pointer to an absolute address,
and then read and write to it. This probably won't work anymore, so you will
have to read your compiler documentation to see how to do it. For better
help, try a platform-specific group.
Nov 14 '05 #8

P: n/a
In <cc**********@oravannahka.helsinki.fi> Joona I Palaste <pa*****@cc.helsinki.fi> writes:
just4me <ju*****@nowhere.com> scribbled the following:
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


What was your C question?


Are you reading impaired? Even if the answer is that there is no
portable way of doing it, it is a perfectly sensible C question.
Furthermore, the C standard provides a solution, it just doesn't
guarantee that it will work.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
Nov 14 '05 #9

P: n/a
In <cc***********@news3.infoave.net> "just4me" <ju*****@nowhere.com> writes:
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


First, you have to figure out how to represent this address as a single
integer. After that, you have to convert this integer to the desired
pointer type. Note that modern operating systems, using virtual memory
and memory protection complicate the issue a lot, or may even make a
solution impossible, unless you're running with administrator privileges.

However, in the days of 16-bit MS-DOS, there was nothing between your
code and the raw hardware, so the solution was straightforward:

unsigned char *p = (unsigned char *)0xFFFF0000;

After that, you could use p to access the EPROM bytes. It might still
work in a compatibility 16-bit environment, if compiled as a 16-bit
application on a Windows system (and it will definitely work under MS-DOS
itself). Use a memory model with 32-bit pointers!

The moral is that, although the code itself is as standard C as you can
get, its effect is highly platform, compiler and operating system
dependent.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
Nov 14 '05 #10

P: n/a
Thanks Dan,

I am using MS-Dos so this is exactly what I was looking for.

"Dan Pop" <Da*****@cern.ch> wrote in message
news:cc**********@sunnews.cern.ch...
In <cc***********@news3.infoave.net> "just4me" <ju*****@nowhere.com> writes:
Exactly how do I read a specific location in the bios eprom.
(such as debug.exe location ffff:0000)


First, you have to figure out how to represent this address as a single
integer. After that, you have to convert this integer to the desired
pointer type. Note that modern operating systems, using virtual memory
and memory protection complicate the issue a lot, or may even make a
solution impossible, unless you're running with administrator privileges.

However, in the days of 16-bit MS-DOS, there was nothing between your
code and the raw hardware, so the solution was straightforward:

unsigned char *p = (unsigned char *)0xFFFF0000;

After that, you could use p to access the EPROM bytes. It might still
work in a compatibility 16-bit environment, if compiled as a 16-bit
application on a Windows system (and it will definitely work under MS-DOS
itself). Use a memory model with 32-bit pointers!

The moral is that, although the code itself is as standard C as you can
get, its effect is highly platform, compiler and operating system
dependent.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de

Nov 14 '05 #11

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