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>  <toc>  <sect>Overview 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 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 its 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 In the standard setup, cc65 generated programs use the memory from $800 to $9600, so 35.5K 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 HIMEM and grows downwards, regardless of how your linker config file is setup. <tag/Heap/ The C heap is located at the end of the program and grows towards the C runtime stack. </descrip> <sect>Platform specific header files Programs containing Apple ][ specific code may use the <tt/apple2.h/ header file. <sect1>Apple ][ specific functions 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 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 Note: 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 Note: Since memory for the high resolution 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 was written by Stefan Haubenthal. It features a resolution of 40×40 with 16 colors. At the bottom of the screen, 4 additional text lines are available. <tag><tt/a2.hi.tgi/</tag> This driver was written by Stefan Haubenthal. It features a resolution of 280×192 with 6 colors. </descrip> <sect1>Extended memory drivers <descrip> <tag><tt/a2.lc.emd/</tag> Gives access to 12KB RAM (48 pages of 256 bytes each) on the Apple ][ language card. The driver was contributed by Stefan Haubenthal. Note: This driver is incompatible with any DOS using the language card memory! </descrip> <sect1>Joystick drivers <descrip> <tag><tt/a2.stdjoy.joy/</tag> Supports up to two standard analog joysticks connected to the game port of the Apple ][. </descrip> <sect1>Mouse drivers Currently no drivers available (in fact, the API for loadable mouse drivers does not exist). <sect1>RS232 device drivers No serial drivers are currently available for the Apple ][. <sect>Limitations<label id="limitations"> <sect1>Disk I/O 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 <sect1>Passing arguments to the program Command line arguments can be passed to <tt/main()/. Since this is not supported by BASIC, the following syntax was choosen: <tscreen><verb> CALL2048:REM,ARG1," ARG2", ARG 3,, ARG5, ... </verb></tscreen> <enum> <item>Arguments are separated by commas. <item>There must be a comma after the first <tt/REM/. <item>Leading spaces are ignored; trailing spaces are included unless the argument was quoted. <item>The first argument passed to <tt/main/ is the program name. </enum> <sect1>Function keys These are defined to be OpenApple + number key. <sect>Bugs/Feedback 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 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>