223cc6685e
git-svn-id: svn://svn.compuextreme.de/Viitor/V963/Viitor_cc65@5933 504e572c-2e33-0410-9681-be2bf7408885
87 lines
2.5 KiB
HTML
87 lines
2.5 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.20">
|
|
<TITLE>ca65 Users Guide: Address sizes and memory models</TITLE>
|
|
<LINK HREF="ca65-8.html" REL=next>
|
|
<LINK HREF="ca65-6.html" REL=previous>
|
|
<LINK HREF="ca65.html#toc7" REL=contents>
|
|
</HEAD>
|
|
<BODY>
|
|
<A HREF="ca65-8.html">Next</A>
|
|
<A HREF="ca65-6.html">Previous</A>
|
|
<A HREF="ca65.html#toc7">Contents</A>
|
|
<HR>
|
|
<H2><A NAME="address-sizes"></A> <A NAME="s7">7.</A> <A HREF="ca65.html#toc7">Address sizes and memory models</A></H2>
|
|
|
|
|
|
|
|
<H2><A NAME="ss7.1">7.1</A> <A HREF="ca65.html#toc7.1">Address sizes</A>
|
|
</H2>
|
|
|
|
|
|
<P>ca65 assigns each segment and each symbol an address size. This is true, even
|
|
if the symbol is not used as an address. You may also think of a value range
|
|
of the symbol instead of an address size.</P>
|
|
<P>Possible address sizes are:</P>
|
|
<P>
|
|
<UL>
|
|
<LI>Zeropage or direct (8 bits)</LI>
|
|
<LI>Absolute (16 bits)</LI>
|
|
<LI>Far (24 bits)</LI>
|
|
<LI>Long (32 bits)</LI>
|
|
</UL>
|
|
</P>
|
|
<P>Since the assembler uses default address sizes for the segments and symbols,
|
|
it is usually not necessary to override the default behaviour. In cases, where
|
|
it is necessary, the following keywords may be used to specify address sizes:</P>
|
|
<P>
|
|
<UL>
|
|
<LI>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).</LI>
|
|
<LI>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).</LI>
|
|
<LI>FAR for far addressing (24 bits).</LI>
|
|
<LI>LONG or DWORD for long addressing (32 bits).</LI>
|
|
</UL>
|
|
</P>
|
|
|
|
|
|
<H2><A NAME="ss7.2">7.2</A> <A HREF="ca65.html#toc7.2">Address sizes of segments</A>
|
|
</H2>
|
|
|
|
|
|
<P>The assembler assigns an address size to each segment. Since the
|
|
representation of a label within this segment is "segment start + offset",
|
|
labels will inherit the address size of the segment they are declared in.</P>
|
|
<P>The address size of a segment may be changed, by using an optional address
|
|
size modifier. See the <CODE>
|
|
<A HREF="ca65-10.html#.SEGMENT">segment directive</A></CODE> for
|
|
an explanation on how this is done.</P>
|
|
|
|
|
|
<H2><A NAME="ss7.3">7.3</A> <A HREF="ca65.html#toc7.3">Address sizes of symbols</A>
|
|
</H2>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<H2><A NAME="ss7.4">7.4</A> <A HREF="ca65.html#toc7.4">Memory models</A>
|
|
</H2>
|
|
|
|
|
|
<P>The default address size of a segment depends on the memory model used. Since
|
|
labels inherit the address size from the segment they are declared in,
|
|
changing the memory model is an easy way to change the address size of many
|
|
symbols at once.</P>
|
|
|
|
|
|
|
|
|
|
<HR>
|
|
<A HREF="ca65-8.html">Next</A>
|
|
<A HREF="ca65-6.html">Previous</A>
|
|
<A HREF="ca65.html#toc7">Contents</A>
|
|
</BODY>
|
|
</HTML>
|