🚀 go-pugleaf

Hello,

I'm running the GNU CC compiler on a IBM PC with MSDOS as OS and want to 
produce a program just for the same machine and OS.

One of the modules of the program has to be written in assembler. So I use 
the gas provided with the C-compiler.

Inside of the assembler module I have to get the printer ports out of the 
BIOS variables.
The problem arises when I try to access the 1st MB of physical memory. 
I got a short notice from the documentation files about the fact that the 
1st MB should be mapped through address 0xE0000000 . But if I try to load 
the ds register with 0xE000 I get a protection error of course. (I think 
it's because I need the right selector in protected mode and not the 
physical address.)

But how could I do it ?? What's the right selector or address for accessing 
the 1st MB of physical memory? Or what other points have I to consider in 
that case.

Thanks in advance if anyone can help me answering the question.

My Email address is 100273.171@compuserve.com



Karsten Rudolph