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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML><HEAD> <META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.20"> <TITLE>Atari specific information for cc65: Memory layout</TITLE> <LINK HREF="atari-4.html" REL=next> <LINK HREF="atari-2.html" REL=previous> <LINK HREF="atari.html#toc3" REL=contents></HEAD><BODY><A HREF="atari-4.html">Next</A><A HREF="atari-2.html">Previous</A><A HREF="atari.html#toc3">Contents</A><HR><H2><A NAME="s3">3.</A> <A HREF="atari.html#toc3">Memory layout</A></H2><P>The default linker script assumes that the BASIC ROM is disabled (orthe BASIC cartridge unplugged). This gives a usable memory range from$2E00 - $BC1F. The library startup code examines thecurrent memory configuration, which depends on the size of theinstalled memory and cartridges present, by inspecting the value inthe MEMTOP ($2E5) variable. Then the initial stack pointer,which indicates the upper bound of memory used, is adjusted. The loadaddress of $2E00 was chosen to accommodate having a DOS loadedand a driver that resides in low memory such as the 850 R: handler.You can override this behaviour by creating a custom linker configfile.</P><P>Special locations:</P><P><DL><DT><B>Text screen</B><DD><P>The text screen depends on the installed memory size and cartridgesand can be obtained from the SAVMSC variable ($58).</P><DT><B>Stack</B><DD><P>The C runtime stack is located at MEMTOP and grows downwards,regardless of how your linker config file is setup. Thisaccomodates the different memory configurations of the Atarimachines, as well as having a cartridge installed. You can overridethis behaviour by writing your own crt0.s file and linking it toyour program.</P><DT><B>Heap</B><DD><P>The C heap is located at the end of the program and grows towards the Cruntime stack.</P></DL></P><HR><A HREF="atari-4.html">Next</A><A HREF="atari-2.html">Previous</A><A HREF="atari.html#toc3">Contents</A></BODY></HTML>⌨️ 快捷键说明
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