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 its 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 high resolution graphics has to be allocated,
121 programs 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 40×40 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
135 280×192 with 6 colors.
140 <sect1>Extended memory drivers<p>
144 <tag><tt/a2-lc.emd/</tag>
145 Gives access to 12KB RAM (48 pages of 256 bytes each) on the
146 Apple ][ language card. The driver was contributed by
153 <sect1>Joystick drivers<p>
157 <tag><tt/a2-stdjoy.joy/</tag>
158 Supports up to two standard analog joysticks connected to the game port of
159 the Apple ][.
165 <sect1>Mouse drivers<p>
167 Currently no drivers available (in fact, the API for loadable mouse drivers
171 <sect1>RS232 device drivers<p>
173 No serial drivers are currently available for the Apple ][.
177 <sect>Limitations<label id="limitations"><p>
181 The existing library for the Apple ][ doesn't implement C file
182 I/O. There are two hacks for the <tt/read()/ and <tt/write()/ routines in
183 place, which will make functions work that read from or write to <tt/stdout/
184 (like <tt/printf()/). However, these functions have some shortcomings which
185 won't be fixed, because they're going to be replaced anyway.
187 To be more concrete, this limitation means that you cannot use any of the
188 following functions (and a few others):
204 <sect1>Passing arguments to the program<p>
206 Command line arguments can be passed to <tt/main()/. Since this is not
207 supported by BASIC, the following syntax was choosen:
210 RUN:REM,ARG1," ARG2", ARG 3,, ARG5, ...
214 <item>Arguments are separated by commas.
215 <item>There must be a comma after the first <tt/REM/.
216 <item>Leading spaces are ignored; trailing spaces are included unless the
218 <item>The first argument passed to <tt/main/ is the program name.
222 <sect1>Function keys<p>
224 These are defined to be OpenApple + number key.
228 <sect>Bugs/Feedback<p>
230 If you have problems using the library, if you find any bugs, or if you're
231 doing something interesting with it, I would be glad to hear from you. Feel
232 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
233 name="uz@cc65.org">).
239 This software is provided 'as-is', without any expressed or implied
240 warranty. In no event will the authors be held liable for any damages
241 arising from the use of this software.
243 Permission is granted to anyone to use this software for any purpose,
244 including commercial applications, and to alter it and redistribute it
245 freely, subject to the following restrictions:
248 <item> The origin of this software must not be misrepresented; you must not
249 claim that you wrote the original software. If you use this software
250 in a product, an acknowledgment in the product documentation would be
251 appreciated but is not required.
252 <item> Altered source versions must be plainly marked as such, and must not
253 be misrepresented as being the original software.
254 <item> This notice may not be removed or altered from any source