1 <!doctype linuxdoc system>
5 <title>Apple ][ specific information for cc65
6 <author><url url="mailto:ol.sc@web.de" name="Oliver Schmidt">
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 <url 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 file format generated by the linker for the
37 Apple ][ target is an <url name="AppleSingle"
38 url="http://kaiser-edv.de/documents/AppleSingle_AppleDouble.pdf"> file.
39 The default load address is $803.
41 <bf/AppleCommander 1.4.0/ or later (available at <url
42 url="https://applecommander.github.io/">) includes the option <tt/-as/ that
43 allows to put AppleSingle files onto disk images containing DOS 3.3 as well
47 <sect>Memory layout<p>
49 In the standard setup, cc65 generated programs use the memory from
50 $803 to $95FF, so 35.5 KB of RAM are available.
57 The C runtime stack is located at HIMEM and grows downwards, regardless of
58 how your linker config file is setup.
61 The C heap is located at the end of the program and grows towards the C
66 While running <tt/main()/ the Language Card bank 2 is enabled for read access.
67 However while running module constructors/destructors the Language Card is disabled.
69 Enabling the Language Card allows to use it as additional memory for cc65
70 generated code. However code is never automatically placed there. Rather code
71 needs to be explicitly placed in the Language Card either per file by compiling
72 with <tt/--code-name LC/ or per function by enclosing in <tt/#pragma code-name
73 (push, "LC")/ and <tt/#pragma code-name (pop)/. In either case the cc65 runtime
74 system takes care of actually moving the code into the Language Card.
76 The amount of memory available in the Language Card for generated code depends
77 on the <ref id="link-configs" name="linker configuration"> parameters. There are
78 several usefull settings:
82 <tag>LC address: $D400, LC size: $C00</tag>
83 For plain vanilla ProDOS 8 which doesn't actually use the Language Card bank 2
84 memory from $D400 to $DFFF. This is the default setting.
86 <tag>LC address: $D000, LC size: $1000</tag>
87 For ProDOS 8 together with the function <tt/rebootafterexit()/. If a program
88 doesn't quit to the ProDOS 8 dispatcher but rather reboots the machine after
89 exit then a plain vanilla ProDOS 8 doesn't make use of the Language Card bank
92 <tag>LC address: $D000, LC size: $3000</tag>
93 For plain vanilla DOS 3.3 which doesn't make use of the Language Card at all.
99 <sect>Linker configurations<label id="link-configs"><p>
101 The ld65 linker comes with a default config file for the Apple ][,
102 which is used via <tt/-t apple2/.
103 The apple2 package comes with additional secondary linker config files, which
104 are used via <tt/-t apple2 -C <configfile>/.
107 <sect1>default config file (<tt/apple2.cfg/)<label id="apple-def-cfg"><p>
109 Default configuration for a binary program.
115 <tag><tt/STARTADDRESS:/ Program start address</tag>
116 Default: $803. Use <tt/-S <addr>/ to set a different start address.
118 <tag><tt/__EXEHDR__:/ AppleSingle executable file header</tag>
119 Default: Yes. Use <tt/-D __EXEHDR__=0/ to omit the AppleSingle header.
121 <tag><tt/__STACKSIZE__:/ C runtime stack size</tag>
122 Default: $800. Use <tt/-D __STACKSIZE__=<size>/ to set a different
125 <tag><tt/__HIMEM__:/ Highest usable memory address presumed at link time</tag>
126 Default: $9600. Use <tt/-D __HIMEM__=<addr>/ to set a different
127 highest usable address.
129 <tag><tt/__LCADDR__:/ Address of code in the Language Card</tag>
130 Default: $D400. Use <tt/-D __LCADDR__=<addr>/ to set a different
133 <tag><tt/__LCSIZE__:/ Size of code in the Language Card</tag>
134 Default: $C00. Use <tt/-D __LCSIZE__=<size>/ to set a different
140 <sect1><tt/apple2-system.cfg/<label id="apple-sys-cfg"><p>
142 Configuration for a system program running on ProDOS 8 and using the memory from
143 $2000 to $BEFF.
149 <tag><tt/__EXEHDR__:/ AppleSingle executable file header</tag>
150 Default: Yes. Use <tt/-D __EXEHDR__=0/ to omit the AppleSingle header.
152 <tag><tt/__STACKSIZE__:/ C runtime stack size</tag>
153 Default: $800. Use <tt/-D __STACKSIZE__=<size>/ to set a different
156 <tag><tt/__LCADDR__:/ Address of code in the Language Card</tag>
157 Default: $D400. Use <tt/-D __LCADDR__=<addr>/ to set a different
160 <tag><tt/__LCSIZE__:/ Size of code in the Language Card</tag>
161 Default: $C00. Use <tt/-D __LCSIZE__=<size>/ to set a different
167 <sect1><tt/apple2-hgr.cfg/<p>
169 Configuration for a program including a hires page. See <tt>testcode/lib/apple/hgrtest.c</tt>
170 for an example of such a program.
176 <tag><tt/STARTADDRESS:/ Program start address</tag>
177 Default: $803. Use <tt/-S <addr>/ to set a different start address.
179 <tag><tt/__EXEHDR__:/ AppleSingle executable file header</tag>
180 Default: Yes. Use <tt/-D __EXEHDR__=0/ to omit the AppleSingle header.
182 <tag><tt/__STACKSIZE__:/ C runtime stack size</tag>
183 Default: $800. Use <tt/-D __STACKSIZE__=<size>/ to set a different
186 <tag><tt/__HIMEM__:/ Highest usable memory address presumed at link time</tag>
187 Default: $9600. Use <tt/-D __HIMEM__=<addr>/ to set a different
188 highest usable address.
190 <tag><tt/__LCADDR__:/ Address of code in the Language Card</tag>
191 Default: $D400. Use <tt/-D __LCADDR__=<addr>/ to set a different
194 <tag><tt/__LCSIZE__:/ Size of code in the Language Card</tag>
195 Default: $C00. Use <tt/-D __LCSIZE__=<size>/ to set a different
201 <sect1><tt/apple2-overlay.cfg/<p>
203 Configuration for an overlay program with up to nine overlays. The overlay files
204 don't include the AppleSingle header. See <tt>samples/overlaydemo.c</tt> for more
205 information on overlays.
211 <tag><tt/STARTADDRESS:/ Program start address</tag>
212 Default: $803. Use <tt/-S <addr>/ to set a different start address.
214 <tag><tt/__EXEHDR__:/ AppleSingle executable file header</tag>
215 Default: Yes. Use <tt/-D __EXEHDR__=0/ to omit the AppleSingle header.
217 <tag><tt/__STACKSIZE__:/ C runtime stack size</tag>
218 Default: $800. Use <tt/-D __STACKSIZE__=<size>/ to set a different
221 <tag><tt/__HIMEM__:/ Highest usable memory address presumed at link time</tag>
222 Default: $9600. Use <tt/-D __HIMEM__=<addr>/ to set a different
223 highest usable address.
225 <tag><tt/__LCADDR__:/ Address of code in the Language Card</tag>
226 Default: $D400. Use <tt/-D __LCADDR__=<addr>/ to set a different
229 <tag><tt/__LCSIZE__:/ Size of code in the Language Card</tag>
230 Default: $C00. Use <tt/-D __LCSIZE__=<size>/ to set a different
233 <tag><tt/__OVERLAYSIZE__:/ Size of code in the overlays</tag>
234 Default: $1000. Use <tt/-D __OVERLAYSIZE__=<size>/ to set a different
240 <sect1><tt/apple2-asm.cfg/<p>
242 Configuration for an assembler program that doesn't need a special setup.
248 <tag><tt/STARTADDRESS:/ Program start address</tag>
249 Default: $803. Use <tt/-S <addr>/ to set a different start address.
251 <tag><tt/__EXEHDR__:/ AppleSingle executable file header</tag>
252 Default: No. Use <tt/-u __EXEHDR__ apple2.lib/ to add the AppleSingle header.
258 <sect>ProDOS 8 system programs<p>
260 ProDOS 8 system programs are always loaded to the start address $2000.
261 For cc65 programs this means that the 6 KB from $800 to $2000 are
262 by default unused. There are however several options to make use of that memory
266 <sect1>LOADER.SYSTEM<p>
268 The easiest (and for really large programs in fact the only) way to have a cc65
269 program use the memory from $800 to $2000 is to link it as binary
270 (as opposed to system) program using the default linker configuration
271 <ref id="apple-def-cfg" name="apple2.cfg"> with <tt/__HIMEM__/ set to $BF00
272 and load it with the LOADER.SYSTEM utility. The program then works like a system
273 program (i.e. quits to the ProDOS dispatcher).
275 Using LOADER.SYSTEM is as simple as copying it to the ProDOS 8 directory of the
276 program to load under name <program>.SYSTEM as a system program. For
277 example the program <tt/MYPROG/ is loaded by <tt/MYPROG.SYSTEM/. The right
278 AppleCommander option to put LOADER.SYSTEM on a ProDOS 8 disk image is <tt/-p/.
283 If the cc65 program can be successfully linked as system program using the linker
284 configuration <ref id="apple-sys-cfg" name="apple2-system.cfg">, but
285 uses the heap either explicitly or implicitly (i.e. by loading a driver) then
286 the memory from $800 to $2000 can be added to the heap by calling
287 <tt/_heapadd ((void *) 0x0800, 0x1800);/ at the beginning of <tt/main()/.
290 <sect1>ProDOS 8 I/O buffers<p>
292 ProDOS 8 requires for every open file a page-aligned 1 KB I/O buffer. By default
293 these buffers are allocated by the cc65 runtime system on the heap using
294 <tt/posix_memalign()/. While this is generally the best solution it means quite
295 some overhead for (especially rather small) cc65 programs which do open files
296 but don't make use of the heap otherwise.
298 The apple2 package comes with the alternative ProDOS 8 I/O buffer allocation
299 module <tt/apple2-iobuf-0800.o/ which uses the memory between $800 and
300 the program start address for the 1 KB I/O buffers. For system programs (with
301 start address $2000) this results in up to 6 I/O buffers and thus up to 6
302 concurrently open files.
304 While using <tt/_heapadd()/ as described in the section above together with the
305 default I/O buffer allocation basically yields the same placement of I/O buffers
306 in memory the primary benefit of <tt/apple2-iobuf-0800.o/ is a reduction in code
307 size - and thus program file size - of more than 1400 bytes.
309 Using <tt/apple2-iobuf-0800.o/ is as simple as placing it on the linker command
313 cl65 -t apple2 -C apple2-system.cfg myprog.c apple2-iobuf-0800.o
318 <sect>Platform specific header files<p>
320 Programs containing Apple ][ specific code may use the
321 <tt/apple2.h/ header file.
324 <sect1>Apple ][ specific functions<p>
326 The functions listed below are special for the Apple ][. See
327 the <url url="funcref.html" name="function reference"> for declaration and
335 <item>rebootafterexit
336 <item>ser_apple2_slot
341 <sect1>Hardware access<p>
343 There's currently no support for direct hardware access. This does not mean
344 you cannot do it, it just means that there's no help.
348 <sect>Loadable drivers<p>
350 The names in the parentheses denote the symbols to be used for static linking of the drivers.
353 <sect1>Graphics drivers<p>
357 <tag><tt/a2.lo.tgi (a2_lo_tgi)/</tag>
358 This driver features a resolution of 40×48 with 16 colors.
360 The function <tt/tgi_apple2_mix()/ allows to activate 4 lines of text. The
361 function clears the corresponding area at the bottom of the screen.
363 <tag><tt/a2.hi.tgi (a2_hi_tgi)/</tag>
364 This driver features a resolution of 280×192 with 8 colors and two
365 hires pages. Note that programs using this driver will have to be linked
366 with <tt/-S $4000/ to reserve the first hires page or with <tt/-S $6000/
367 to reserve both hires pages.
369 The function <tt/tgi_apple2_mix()/ allows to activate 4 lines of text. The
370 function doesn't clear the corresponding area at the bottom of the screen.
372 In memory constrained situations the memory from $803 to $1FFF
373 can be made available to a program by calling <tt/_heapadd ((void *) 0x0803, 0x17FD);/
374 at the beginning of <tt/main()/. Doing so is beneficial even if the program
375 doesn't use the the heap explicitly because loading the driver (and in fact
376 already opening the driver file) uses the heap implicitly.
381 <sect1>Extended memory drivers<p>
385 <tag><tt/a2.auxmem.emd (a2_auxmem_emd)/</tag>
386 Gives access to 47.5 KB RAM (190 pages of 256 bytes each) on an Extended
389 Note that this driver doesn't check for the actual existence of the memory
390 and that it doesn't check for ProDOS 8 RAM disk content!
395 <sect1>Joystick drivers<p>
399 <tag><tt/a2.stdjoy.joy (a2_stdjoy_joy)/</tag>
400 Supports up to two standard analog joysticks connected to the game port of
401 the Apple ][.
406 <sect1>Mouse drivers<p>
410 <tag><tt/a2.stdmou.mou (a2_stdmou_mou)/</tag>
411 Driver for the AppleMouse II Card. Searches all Apple II slots
412 for an AppleMouse II Card compatible firmware. The default bounding
413 box is [0..279,0..191].
415 Programs using this driver will have to be linked with <tt/-S $4000/
416 to reserve the first hires page if they are intended to run on an
417 Apple ][ (in contrast to an Apple //e) because the
418 AppleMouse II Card firmware writes to the hires page when initializing
421 Note that the Apple ][ default mouse callbacks support text
427 <sect1>RS232 device drivers<p>
431 <tag><tt/a2.ssc.ser (a2_ssc_ser)/</tag>
432 Driver for the Apple II Super Serial Card. Supports up to 19200 baud,
433 hardware flow control (RTS/CTS) and interrupt driven receives. Note
434 that because of the peculiarities of the 6551 chip transmits are not
435 interrupt driven, and the transceiver blocks if the receiver asserts
436 flow control because of a full buffer.
438 The driver defaults to slot 2. Call <tt/ser_apple2_slot()/ prior to
439 <tt/ser_open()/ in order to select a different slot. <tt/ser_apple2_slot()/
440 succeeds for all Apple II slots, but <tt/ser_open()/ fails with
441 <tt/SER_ERR_NO_DEVICE/ if there's no SSC firmware found in the selected slot.
452 Although the standard binaries generated by the linker for the Apple ][
453 generally run both on DOS 3.3 (with Applesoft BASIC) and on ProDOS 8 (with
454 BASIC.SYSTEM) there are some limitations for DOS 3.3:
458 <tag>Disk File I/O</tag>
459 There's no disk file I/O support. Any attempt to use it yields an error with
460 <tt/errno/ set to <tt/ENOSYS/. This implicitly means that loadable drivers
461 are in general not functional as they depend on disk file I/O. Therefore the statically
462 linked drivers have to be used instead.
465 There's no <tt/interruptor/ support. Any attempt to use it yields the message
466 'FAILED TO ALLOC INTERRUPT' on program startup. This implicitly means that
467 mouse and RS232 device drivers are not functional as they depend on interrupts.
472 <sect1>Direct console I/O<p>
477 The Apple ][ has no color text mode. Therefore the functions textcolor(),
478 bgcolor() and bordercolor() have no effect.
487 <sect1>Passing arguments to the program<p>
489 Command line arguments can be passed to <tt/main()/ after BLOAD. Since this is not
490 supported by BASIC, the following syntax was chosen:
493 ]CALL2051:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
497 <item>Arguments are separated by spaces.
498 <item>Arguments may be quoted.
499 <item>Leading and trailing spaces around an argument are ignored. Spaces within
500 a quoted argument are allowed.
501 <item>The first argument passed to <tt/main/ is the program name.
502 <item>A maximum number of 10 arguments (including the program name) are
509 The runtime for the Apple ][ uses routines marked as
510 <tt/.INTERRUPTOR/ for ProDOS 8 interrupt handlers. Such routines must be
511 written as simple machine language subroutines and will be called
512 automatically by the interrupt handler code when they are linked into a
513 program. See the discussion of the <tt/.CONDES/ feature in the <url
514 url="ca65.html" name="assembler manual">.
522 The function <url url="dio.html#s1" name="dio_open()"> has the single
523 parameter <tt/device/ to identify the device to be opened. Therefore an
524 Apple II slot and drive pair is mapped to that <tt/device/ according
528 device = slot + (drive - 1) * 8
531 so that for example slot 6 drive 2 is mapped to <tt/device/ 14.
534 The function <url url="dio.html#s3" name="dio_query_sectcount()"> returns
535 the correct sector count for all ProDOS 8 disks. However for any non-ProDOS 8
536 disk it simply always returns 280 (which is only correct for a 140 KB disk).
537 This condition is indicated by the <tt/_oserror/ value 82.
542 <sect1>Specifying file types for fopen<p>
546 <tag>Explanation of File Types</tag>
548 ProDOS associates a file type and an auxiliary type with each file.
549 These type specifications are separate from the file's name, unlike
550 Windows which uses the file name's suffix (a.k.a.
551 extension) to specify the file type. For example, <tt/.exe/,
552 <tt/.doc/, or <tt/.bat/.
554 Machine-Language Interface (MLI) functions for creating and opening
555 files require these types to be specified. And if they don't match
556 with the file being opened, the operation may fail.
558 In contrast, the ISO C function <tt/fopen()/ and the POSIX function
559 <tt/open()/ have no parameter to specify either a file type or an
560 auxiliary type. Therefore, some additional mechanism for specifying
561 the file types is needed.
563 <tag>Specifying the File Type and Auxiliary Type</tag>
565 There are two global variables provided that allow the file type
566 and auxiliary type to be specified before a call to <tt/fopen()/
567 or <tt/open()/. They are defined in <tt/apple2_filetype.h/:
571 extern unsigned char _filetype; /* Default: PRODOS_T_BIN */
572 extern unsigned int _auxtype; /* Default: 0 */
576 The header file <tt/apple2_filetype.h/ also defines many values
577 that can be used to set these variables. It is included in
578 <tt/apple2.h/, which is in turn included in <tt/apple2enh.h/.
579 So it isn't necessary to include it directly. Just
580 include one of <tt/apple2.h/ or <tt/apple2enh.h/.
584 A text file cannot be created with just the
585 standard C functions because they default to the binary type
586 <tt/PRODOS_T_BIN/. The <tt/_filetype/ variable must be set to
587 <tt/PRODOS_T_TXT/ to create a text file.
590 <tt/_auxtype/ specifies the record length. A zero record
591 length text file is referred to as a sequential text file.
592 This is equivalent to text files on
593 other operating systems, except that the line terminator is a
594 carriage return instead of a line-feed (Linux/BSD/MacOS) or
595 carriage return, line-feed pair (Windows).
597 The "sequential" text file terminology is in contrast to a
598 "random-access" text file which would
599 have a fixed-length, non-zero record length, so that the
600 file position of any individual record can be calculated.
602 For this example, the
603 <tt/_auxtype/ does not need to be set because it defaults to
604 the desired value, which is zero. To be more explicit,
605 <tt/_auxtype/ can also be set to <tt/PRODOS_AUX_T_TXT_SEQ/
606 which is defined as zero.
610 #include <stdio.h>
611 #include <string.h>
612 #include <errno.h>
613 #include <apple2.h>
618 char *name = "MY.FAVS";
620 /*-----------------------------*/
622 _filetype = PRODOS_T_TXT;
623 _auxtype = PRODOS_AUX_T_TXT_SEQ;
625 /*-----------------------------*/
627 if ((out = fopen(name, "w")) != NULL) {
628 fputs("Jorah Mormont\r", out);
629 fputs("Brienne of Tarth\r", out);
630 fputs("Daenerys Targaryen\r", out);
631 fputs("Sandor Clegane\r", out);
632 if (fclose(out) == EOF) {
633 fprintf(stderr, "fclose failed for %s: %s", name, strerror(errno));
637 fprintf(stderr, "fopen failed for %s: %s", name, strerror(errno));
648 This software is provided 'as-is', without any expressed or implied
649 warranty. In no event will the authors be held liable for any damages
650 arising from the use of this software.
652 Permission is granted to anyone to use this software for any purpose,
653 including commercial applications, and to alter it and redistribute it
654 freely, subject to the following restrictions:
657 <item> The origin of this software must not be misrepresented; you must not
658 claim that you wrote the original software. If you use this software
659 in a product, an acknowledgment in the product documentation would be
660 appreciated but is not required.
661 <item> Altered source versions must be plainly marked as such, and must not
662 be misrepresented as being the original software.
663 <item> This notice may not be removed or altered from any source