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
34 <sect>Binary format<p>
36 The standard binary output format generated by the linker for the
37 Apple ][ target is a machine language program with a 4 byte DOS
38 3.3 header containing the load address and load size. The standard load address
41 The DOS 3.3 header is in its own segment named <tt/EXEHDR/. If you don't want
42 the header for some reason, you can change
45 HEADER: start = $0000, size = $0004, file = %O;
51 HEADER: start = $0000, size = $0004, file = "";
54 in the linker configuration to have the linker remove it.
56 <bf/AppleCommander 1.3.5/ or later (available at <url
57 url="http://applecommander.sourceforge.net/">) includes an option <tt/-cc65/
58 that allows to put binary files with the DOS 3.3 header onto disk images
59 containing either DOS 3.3 or ProDOS 8.
61 Please note that there is an <bf/Apple ][ ProDOS 8 system program
62 for loading binary programs/ available in the cc65 User Contributions section.
63 It adds all benefits of a ProDOS 8 system program to the standard binary
64 program generated by the linker for the Apple ][ target.
68 <sect>Memory layout<p>
70 In the standard setup, cc65 generated programs use the memory from
71 $803 to $95FF, so 35.5KB of RAM are available. While running
72 <tt/main()/ the Language Card bank 2 is enabled for read access. However while
73 running module constructors/destructors the Language Card is disabled.
79 The C runtime stack is located at HIMEM and grows downwards, regardless of
80 how your linker config file is setup.
83 The C heap is located at the end of the program and grows towards the C
87 Enabling the Language Card allows to use it as additional memory for executable
88 code. Actually doing so requires either to compile code with the option
89 <tt/--code-name HIGHCODE/ or to use <tt/#pragma codeseg ("HIGHCODE")/.
91 The amount of memory available in the Language Card for executable code depends
92 on the chosen program environment. A plain vanilla ProDOS 8 doesn't actually
93 use the Language Card bank 2 memory from $D400 to $DFFF.
94 Therefore the builtin linker configuration defines these 3KB as <tt/LC/ memory
95 area for executable code.
97 A plain vanilla DOS 3.3 doesn't make use of the Language Card at all. So you
101 LC: start = $D400, size = $0C00, define = yes;
107 LC: start = $D000, size = $3000, define = yes;
110 in the linker configuration to define the whole 12KB Language Card address
111 space as memory area for executable code.
115 <sect>Platform specific header files<p>
117 Programs containing Apple ][ specific code may use the
118 <tt/apple2.h/ header file.
121 <sect1>Apple ][ specific functions<p>
123 The functions listed below are special for the Apple ][. See
124 the <htmlurl url="funcref.html" name="function reference"> for declaration and
133 <sect1>Hardware access<p>
135 There's currently no support for direct hardware access. This does not mean
136 you cannot do it, it just means that there's no help.
140 <sect>Loadable drivers<p>
143 <sect1>Graphics drivers<p>
147 <tag><tt/a2.lo.tgi/</tag>
148 This driver features a resolution of 40×48 with 16 colors.
150 <tag><tt/a2.hi.tgi/</tag>
151 This driver features a resolution of 280×192 with 8 colors and two
152 hires pages. Note that programs using this driver will have to be linked
153 with <tt/--start-addr $4000/ to reserve the first hires page or with
154 <tt/--start-addr $6000/ to reserve both hires pages.
156 In memory constrained situations the memory from $803 to $1FFF
157 can be made available to a program by executing <tt/_heapadd ((void *) 0x0803, 0x17FD);/
158 at the beginning of <tt/main()/. Doing so is beneficial even if the program
159 doesn't use the the heap explicitly because loading the driver (and in fact
160 already opening the driver file) uses the heap implicitly.
165 <sect1>Extended memory drivers<p>
169 <tag><tt/a2.auxmem.emd/</tag>
170 Gives access to 47,5 KB RAM (190 pages of 256 bytes each) on an Extended
173 Note that this driver doesn't check for the actual existence of the memory
174 and that it doesn't check for ProDOS 8 RAM disk content!
179 <sect1>Joystick drivers<p>
183 <tag><tt/a2.stdjoy.joy/</tag>
184 Supports up to two standard analog joysticks connected to the game port of
185 the Apple ][.
190 <sect1>Mouse drivers<p>
194 <tag><tt/a2.stdmou.mou/</tag>
195 Driver for the AppleMouse II Card. Searches all Apple II slots
196 for an AppleMouse II Card compatible firmware. The default bounding
197 box is [0..279,0..191].
199 Programs using this driver will have to be linked with <tt/--start-addr $4000/
200 to reserve the first hires page if they are intended to run on an
201 Apple ][ (in contrast to an Apple //e) because the
202 AppleMouse II Card firmware writes to the hires page when initializing
205 Note that the Apple ][ default mouse callbacks support text
211 <sect1>RS232 device drivers<p>
215 <tag><tt/a2.ssc.ser/</tag>
216 Driver for the Apple II Super Serial Card. Supports up to 19200 baud,
217 hardware flow control (RTS/CTS) and interrupt driven receives. Note
218 that because of the peculiarities of the 6551 chip transmits are not
219 interrupt driven, and the transceiver blocks if the receiver asserts
220 flow control because of a full buffer.
222 The driver defaults to slot 2. Call <tt/ser_ioctl(0, <slot>)/ prior to
223 <tt/ser_open()/ in order to select a different slot. <tt/ser_ioctl()/
224 succeeds for all Apple II slots, but <tt/ser_open()/ fails with
225 <tt/SER_ERR_NO_DEVICE/ if there's no SSC firmware found in the selected slot.
233 <sect1>DOS 3.3 Limitations<p>
235 Although the standard binaries generated by the linker for the Apple ][
236 generally run both on DOS 3.3 (with Applesoft BASIC) and on ProDOS 8 (with
237 BASIC.SYSTEM) there are some limitations for DOS 3.3:
241 <tag>Disk File I/O</tag>
242 There's no disk file I/O support. Any attempt to use it yields an error with
243 <tt/errno/ set to <tt/ENOSYS/. This implicitly means that loadable drivers
244 are in general not functional as they depend on disk file I/O. However they
245 may be converted to statically linked drivers using the co65 object-file
248 <tag>Interrupts</tag>
249 There's no <tt/interruptor/ support. Any attempt to use it yields the message
250 'FAILED TO ALLOC INTERRUPT' on program startup. This implicitly means that
251 <tt/a2.stdmou.mou/ and <tt/a2.ssc.ser/ are not functional as they depend on
261 <sect1>Passing arguments to the program<p>
263 Command line arguments can be passed to <tt/main()/ after BLOAD. Since this is not
264 supported by BASIC, the following syntax was chosen:
267 ]CALL2051:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
271 <item>Arguments are separated by spaces.
272 <item>Arguments may be quoted.
273 <item>Leading and trailing spaces around an argument are ignored. Spaces within
274 a quoted argument are allowed.
275 <item>The first argument passed to <tt/main/ is the program name.
276 <item>A maximum number of 10 arguments (including the program name) are
283 The runtime for the Apple ][ uses routines marked as <tt/.CONDES/
284 type <tt/interruptor/ for ProDOS 8 interrupt handlers. Such routines must be
285 written as simple machine language subroutines and will be called automatically
286 by the interrupt handler code when they are linked into a program. See the
287 discussion of the <tt/.CONDES/ feature in the <htmlurl url="ca65.html"
288 name="assembler manual">.
292 <sect>Bugs/Feedback<p>
294 If you have problems using the library, if you find any bugs, or if you're
295 doing something interesting with it, I would be glad to hear from you. Feel
296 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
297 name="uz@cc65.org">).
303 This software is provided 'as-is', without any expressed or implied
304 warranty. In no event will the authors be held liable for any damages
305 arising from the use of this software.
307 Permission is granted to anyone to use this software for any purpose,
308 including commercial applications, and to alter it and redistribute it
309 freely, subject to the following restrictions:
312 <item> The origin of this software must not be misrepresented; you must not
313 claim that you wrote the original software. If you use this software
314 in a product, an acknowledgment in the product documentation would be
315 appreciated but is not required.
316 <item> Altered source versions must be plainly marked as such, and must not
317 be misrepresented as being the original software.
318 <item> This notice may not be removed or altered from any source