--- /dev/null
+<!doctype linuxdoc system>
+
+<article>
+
+<title>Apple ][ specific information for cc65
+<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
+<date>2003-12-16
+
+<abstract>
+An overview over the Apple ][ runtime system as it is
+implemented for the cc65 C compiler.
+</abstract>
+
+<!-- Table of contents -->
+<toc>
+
+<!-- Begin the document -->
+
+<sect>Overview<p>
+
+This file contains an overview of the Apple ][ runtime system
+as it comes with the cc65 C compiler. It describes the memory layout,
+Apple ][ specific header files, available drivers, and any
+pitfalls specific to that platform.
+
+Please note that Apple ][ specific functions are just mentioned
+here, they are described in detail in the separate <htmlurl url="funcref.html"
+name="function reference">. Even functions marked as "platform dependent" may
+be available on more than one platform. Please see the function reference for
+more information.
+
+
+<sect>Binary format<p>
+
+The standard binary output format generated by the linker for the
+Apple ][ target is a machine language program with a 4 byte DOS
+3.3 header. The standard load address is $800.
+
+The DOS header is in it's own segment named <tt/EXEHDR/. If you don't want the
+header for some reason, you can change
+
+<verb>
+ HEADER: start = $0000, size = $4, file = %O;
+</verb>
+
+to
+
+<verb>
+ HEADER: start = $0000, size = $4, file = "";
+</verb>
+
+in the linker configuration to have the linker remove it.
+
+
+
+<sect>Memory layout<p>
+
+In the standard setup, cc65 generated programs use the memory from
+$800 to $8E00, so 33.5K of memory (including the stack) is
+available. ROM calls are possible without further precautions.
+
+Special locations:
+
+<descrip>
+ <tag/Stack/
+ The C runtime stack is located at $8DFF and growing downwards.
+
+ <tag/Heap/
+ The C heap is located at the end of the program and grows towards the C
+ runtime stack.
+</descrip><p>
+
+
+
+<sect>Platform specific header files<p>
+
+Programs containing Apple ][ specific code may use the
+<tt/apple2.h/ header file.
+
+
+<sect1>Apple ][ specific functions<p>
+
+The functions listed below are special for the Apple ][. See
+the <htmlurl url="funcref.html" name="function reference"> for declaration and
+usage.
+
+<itemize>
+<item>get_ostype
+</itemize>
+
+
+
+<sect1>Hardware access<p>
+
+There's currently no support for direct hardware access. This does not mean
+you cannot do it, it just means that there's no help.
+
+
+
+<sect>Loadable drivers<p>
+
+<em>Note:</em> Since the Apple ][ doesn't have working disk I/O
+(see <ref id="limitations" name="section "Limitations"">), the
+available drivers cannot be loaded at runtime (so the term "loadable drivers"
+is somewhat misleading). Instead, the drivers have to be converted using the
+<htmlurl url="co65.html" name="co65 utility"> and statically linked. While
+this may seem overhead, it has two advantages:
+
+<enum>
+<item>The interface is identical to the one used for other platforms
+ and to the one for the Apple ][ once it has disk I/O.
+<item>Once disk I/O is available, existing code can be changed to load drivers
+ at runtime with almost no effort.
+</enum>
+
+
+
+<sect1>Graphics drivers<p>
+
+<em>Note:</em> Since memory for the graphics has to be allocated, programs
+using graphics drivers will have to be linked using a special linker
+configuration. See the <tt/apple2-tgi.cfg/ file in the documentation
+directory, and the <htmlurl url="ld65.html" name="linker documentation"> on
+how to use it.
+
+<descrip>
+
+ <tag><tt/a2-lo.tgi/</tag>
+ This driver features a resolution of 40x40 with 16 colors. At the bottom of
+ the screen, 4 additional text lines are available.
+
+ <tag><tt/a2-hi.tgi/</tag>
+ This driver features a resolution of 280x192 with 6 colors.
+
+</descrip><p>
+
+
+<sect1>Extended memory drivers<p>
+
+No extended memory drivers are currently available for the
+Apple ][.
+
+
+
+<sect1>Joystick drivers<p>
+
+<descrip>
+
+ <tag><tt/a2-stdjoy.joy/</tag>
+ Supports up to two standard joysticks connected to the joysticks port of
+ the Apple ][.
+
+</descrip><p>
+
+
+
+<sect1>Mouse drivers<p>
+
+Currently no drivers available (in fact, the API for loadable mouse drivers
+does not exist).
+
+
+<sect1>RS232 device drivers<p>
+
+No serial drivers are currently available for the Apple ][.
+
+
+
+<sect>Limitations<label id="limitations"><p>
+
+<sect1>Disk I/O<p>
+
+The existing library for the Apple ][ doesn't implement C file
+I/O. There are two hacks for the <tt/read()/ and <tt/write()/ routines in
+place, which will make functions work that read from or write to <tt/stdout/
+(like <tt/printf()/). However, these functions have some shortcomings which
+won't be fixed, because they're going to be replaced anyway.
+
+To be more concrete, this limitation means that you cannot use any of the
+following functions (and a few others):
+
+<itemize>
+<item>fclose
+<item>fopen
+<item>fread
+<item>fprintf
+<item>fputc
+<item>fscanf
+<item>fwrite
+<item>...
+</itemize>
+
+
+<sect>Other hints<p>
+
+<sect1>Passing arguments to the program<p>
+
+Command line argument passing is currently not supported for the
+Apple ][.
+
+
+
+<sect>Bugs/Feedback<p>
+
+If you have problems using the library, if you find any bugs, or if you're
+doing something interesting with it, I would be glad to hear from you. Feel
+free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
+name="uz@cc65.org">).
+
+
+
+<sect>License<p>
+
+This software is provided 'as-is', without any expressed or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+<enum>
+<item> The origin of this software must not be misrepresented; you must not
+ claim that you wrote the original software. If you use this software
+ in a product, an acknowledgment in the product documentation would be
+ appreciated but is not required.
+<item> Altered source versions must be plainly marked as such, and must not
+ be misrepresented as being the original software.
+<item> This notice may not be removed or altered from any source
+ distribution.
+</enum>
+
+</article>
+
+
+
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