1 <!doctype linuxdoc system>
5 <title>Apple ][ specific information for cc65
6 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
10 An overview over the Apple ][ runtime system as it is
11 implemented for the cc65 C compiler.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 This file contains an overview of the Apple ][ runtime system
22 as it comes with the cc65 C compiler. It describes the memory layout,
23 Apple ][ specific header files, available drivers, and any
24 pitfalls specific to that platform.
26 Please note that Apple ][ specific functions are just mentioned
27 here, they are described in detail in the separate <htmlurl url="funcref.html"
28 name="function reference">. Even functions marked as "platform dependent" may
29 be available on more than one platform. Please see the function reference for
33 <sect>Binary format<p>
35 The standard binary output format generated by the linker for the
36 Apple ][ target is a machine language program with a 4 byte DOS
37 3.3 header. The standard load address is $800.
39 The DOS header is in it's own segment named <tt/EXEHDR/. If you don't want the
40 header for some reason, you can change
43 HEADER: start = $0000, size = $4, file = %O;
49 HEADER: start = $0000, size = $4, file = "";
52 in the linker configuration to have the linker remove it.
56 <sect>Memory layout<p>
58 In the standard setup, cc65 generated programs use the memory from
59 $800 to $8E00, so 33.5K of memory (including the stack) is
60 available. ROM calls are possible without further precautions.
66 The C runtime stack is located at $8DFF and growing downwards.
69 The C heap is located at the end of the program and grows towards the C
75 <sect>Platform specific header files<p>
77 Programs containing Apple ][ specific code may use the
78 <tt/apple2.h/ header file.
81 <sect1>Apple ][ specific functions<p>
83 The functions listed below are special for the Apple ][. See
84 the <htmlurl url="funcref.html" name="function reference"> for declaration and
93 <sect1>Hardware access<p>
95 There's currently no support for direct hardware access. This does not mean
96 you cannot do it, it just means that there's no help.
100 <sect>Loadable drivers<p>
102 <em>Note:</em> Since the Apple ][ doesn't have working disk I/O
103 (see <ref id="limitations" name="section "Limitations"">), the
104 available drivers cannot be loaded at runtime (so the term "loadable drivers"
105 is somewhat misleading). Instead, the drivers have to be converted using the
106 <htmlurl url="co65.html" name="co65 utility"> and statically linked. While
107 this may seem overhead, it has two advantages:
110 <item>The interface is identical to the one used for other platforms
111 and to the one for the Apple ][ once it has disk I/O.
112 <item>Once disk I/O is available, existing code can be changed to load drivers
113 at runtime with almost no effort.
118 <sect1>Graphics drivers<p>
120 <em>Note:</em> Since memory for the graphics has to be allocated, programs
121 using graphics drivers will have to be linked using a special linker
122 configuration. See the <tt/apple2-tgi.cfg/ file in the documentation
123 directory, and the <htmlurl url="ld65.html" name="linker documentation"> on
128 <tag><tt/a2-lo.tgi/</tag>
129 This driver was written by Stefan Haubenthal. It features a resolution of
130 40x40 with 16 colors. At the bottom of the screen, 4 additional text lines
133 <tag><tt/a2-hi.tgi/</tag>
134 This driver was written by Stefan Haubenthal. It features a resolution of
135 280x192 with 6 colors.
140 <sect1>Extended memory drivers<p>
142 No extended memory drivers are currently available for the
143 Apple ][.
147 <sect1>Joystick drivers<p>
151 <tag><tt/a2-stdjoy.joy/</tag>
152 Supports up to two standard joysticks connected to the joysticks port of
153 the Apple ][.
159 <sect1>Mouse drivers<p>
161 Currently no drivers available (in fact, the API for loadable mouse drivers
165 <sect1>RS232 device drivers<p>
167 No serial drivers are currently available for the Apple ][.
171 <sect>Limitations<label id="limitations"><p>
175 The existing library for the Apple ][ doesn't implement C file
176 I/O. There are two hacks for the <tt/read()/ and <tt/write()/ routines in
177 place, which will make functions work that read from or write to <tt/stdout/
178 (like <tt/printf()/). However, these functions have some shortcomings which
179 won't be fixed, because they're going to be replaced anyway.
181 To be more concrete, this limitation means that you cannot use any of the
182 following functions (and a few others):
198 <sect1>Passing arguments to the program<p>
200 Command line argument passing is currently not supported for the
201 Apple ][.
205 <sect>Bugs/Feedback<p>
207 If you have problems using the library, if you find any bugs, or if you're
208 doing something interesting with it, I would be glad to hear from you. Feel
209 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
210 name="uz@cc65.org">).
216 This software is provided 'as-is', without any expressed or implied
217 warranty. In no event will the authors be held liable for any damages
218 arising from the use of this software.
220 Permission is granted to anyone to use this software for any purpose,
221 including commercial applications, and to alter it and redistribute it
222 freely, subject to the following restrictions:
225 <item> The origin of this software must not be misrepresented; you must not
226 claim that you wrote the original software. If you use this software
227 in a product, an acknowledgment in the product documentation would be
228 appreciated but is not required.
229 <item> Altered source versions must be plainly marked as such, and must not
230 be misrepresented as being the original software.
231 <item> This notice may not be removed or altered from any source