OSDev.org

Do you know a good tutorial on memory mapping and management?
I use Nasm and Tcc.

Tim Robinson wrote two great tut's on memory management.  I don't recall where they can be found, but I'm sure just search for his name and "memory management" on google will pop up a link.

Jeff

The tutorials you speak of can be found at:
http://osdev.neopages.net/tutorials/memory1.php
and
http://osdev.neopages.net/tutorials/memory2.php

Hope this helps