1 <!doctype linuxdoc system>
5 <title>Enhanced Apple //e specific information for cc65
6 <author><url url="mailto:ol.sc@web.de" name="Oliver Schmidt">
10 An overview over the enhanced Apple //e 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 enhanced Apple //e runtime system
22 as it comes with the cc65 C compiler. It describes the memory layout,
23 enhanced Apple //e specific header files, available drivers, and any
24 pitfalls specific to that platform.
26 Please note that enhanced Apple //e 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 enhanced Apple //e target is a binary program with a 4 byte DOS 3.3 header
38 containing the load address and load length. The default load address is
41 <bf/AppleCommander 1.3.5/ or later (available at <url
42 url="http://applecommander.sourceforge.net/">) includes the option <tt/-cc65/
43 that allows to put binary files with a DOS 3.3 header onto disk images
44 containing DOS 3.3 as well as ProDOS 8.
46 For ProDOS 8 system programs the load address is fixed to $2000 so there
47 is no need for a header. Thus the linker configuration
48 <ref id="apple-sys-cfg" name="apple2enh-system.cfg"> for those programs
49 omits the DOS 3.3 header. The right AppleCommander option to put system files
50 without a header on a ProDOS 8 disk image is <tt/-p/.
53 <sect>Memory layout<p>
55 In the standard setup, cc65 generated programs use the memory from
56 $803 to $95FF, so 35.5 KB of RAM are available.
63 The C runtime stack is located at HIMEM and grows downwards, regardless of
64 how your linker config file is setup.
67 The C heap is located at the end of the program and grows towards the C
72 While running <tt/main()/ the Language Card bank 2 is enabled for read access.
73 However while running module constructors/destructors the Language Card is disabled.
75 Enabling the Language Card allows to use it as additional memory for cc65
76 generated code. However code is never automatically placed there. Rather code
77 needs to be explicitly placed in the Language Card either per file by compiling
78 with <tt/--code-name HIGHCODE/ or per function by enclosing in <tt/#pragma
79 code-name (push, "HIGHCODE")/ and <tt/#pragma code-name (pop)/. In either case the
80 cc65 runtime system takes care of actually moving the code into the Language
83 The amount of memory available in the Language Card for generated code depends
84 on the chosen <ref id="link-configs" name="linker configuration">.
88 <sect>Linker configurations<label id="link-configs"><p>
90 The ld65 linker comes with a default config file for the enhanced Apple //e,
91 which is used via <tt/-t apple2enh/.
92 The apple2enh package comes with additional secondary linker config files, which
93 are used via <tt/-t apple2enh -C <configfile>/.
96 <sect1>default config file (<tt/apple2enh.cfg/)<p>
98 Default configuration optimized for a binary program running on ProDOS 8 with
99 BASIC.SYSTEM. A plain vanilla ProDOS 8 doesn't actually use the Language Card
100 bank 2 memory from $D400 to $DFFF.
104 <tag><tt/RAM:/ Main memory area</tag>
105 From $803 to $95FF (35.5 KB)
107 <tag><tt/LC:/ Language Card memory area</tag>
108 From $D400 to $DFFF (3 KB)
110 <tag><tt/STARTADDRESS:/ Program start address</tag>
111 Variable (default: $803)
113 <tag><tt/HEADER:/ Binary file header</tag>
114 DOS 3.3 header (address and length)
119 <sect1><tt/apple2enh-dos33.cfg/<p>
121 Configuration optimized for a binary program running on DOS 3.3. A plain
122 vanilla DOS 3.3 doesn't make use of the Language Card at all.
126 <tag><tt/RAM:/ Main memory area</tag>
127 From $803 to $95FF (35.5 KB)
129 <tag><tt/LC:/ Language Card memory area</tag>
130 From $D000 to $FFFF (12 KB)
132 <tag><tt/STARTADDRESS:/ Program start address</tag>
133 Variable (default: $803)
135 <tag><tt/HEADER:/ Binary file header</tag>
136 DOS 3.3 header (address and length)
141 <sect1><tt/apple2enh-system.cfg/<label id="apple-sys-cfg"><p>
143 Configuration for a system program running on ProDOS 8.
147 <tag><tt/RAM:/ Main memory area</tag>
148 From $2000 to $BEFF (39.75 KB)
150 <tag><tt/LC:/ Language Card memory area</tag>
151 From $D400 to $DFFF (3 KB)
153 <tag><tt/STARTADDRESS:/ Program start address</tag>
156 <tag><tt/HEADER:/ Binary file header</tag>
162 <sect1><tt/apple2enh-loader.cfg/<label id="apple-load-cfg"><p>
164 Configuration optimized for a binary program running on ProDOS 8 without
165 BASIC.SYSTEM. Intended to be used with <bf/LOADER.SYSTEM - an
166 Apple ][ ProDOS 8 loader for cc65 programs/, which is available
167 in the cc65 User Contributions section.
169 A program loaded by LOADER.SYSTEM works like a ProDOS 8 system program but
170 isn't tied to the start address $2000. Thus with the default start
171 address $800 the main memory area is increased by 6 KB.
175 <tag><tt/RAM:/ Main memory area</tag>
176 From $800 to $BEFF (45.75 KB)
178 <tag><tt/LC:/ Language Card memory area</tag>
179 From $D400 to $DFFF (3 KB)
181 <tag><tt/STARTADDRESS:/ Program start address</tag>
182 Variable (default: $800)
184 <tag><tt/HEADER:/ Binary file header</tag>
185 DOS 3.3 header (address and length)
190 <sect1><tt/apple2enh-reboot.cfg/<p>
192 Configuration optimized for a binary program running on ProDOS 8 without
193 BASIC.SYSTEM. Intended to be used with <bf/LOADER.SYSTEM - an
194 Apple ][ ProDOS 8 loader for cc65 programs/ (see above) together
195 with the function <tt/rebootafterexit()/.
197 If a ProDOS 8 system program doesn't quit to the ProDOS 8 dispatcher but rather
198 reboots the machine after exit then a plain vanilla ProDOS 8 doesn't make use of
199 the Language Card bank 2 at all.
201 This setup makes nearly 50 KB available to a cc65 program - on a 64 KB machine!
205 <tag><tt/RAM:/ Main memory area</tag>
206 From $800 to $BEFF (45.75 KB)
208 <tag><tt/LC:/ Language Card memory area</tag>
209 From $D000 to $DFFF (4 KB)
211 <tag><tt/STARTADDRESS:/ Program start address</tag>
212 Variable (default: $800)
214 <tag><tt/HEADER:/ Binary file header</tag>
215 DOS 3.3 header (address and length)
221 <sect>ProDOS 8 system programs<p>
223 ProDOS 8 system programs are always loaded to the start address $2000.
224 For cc65 programs this means that the 6 KB from $800 to $2000 are
225 by default unused. There are however several options to make use of that memory
229 <sect1>LOADER.SYSTEM<p>
231 The easiest (and for really large programs in fact the only) way to have a cc65
232 program use the memory from $800 to $2000 is to link it as binary
233 (as opposed to system) program using the linker configuration
234 <ref id="apple-load-cfg" name="apple2enh-loader.cfg"> with start address
235 $803 and load it with the targetutil LOADER.SYSTEM. The program then works
236 like a system program (i.e. quits to the ProDOS dispatcher).
238 Using LOADER.SYSTEM is as simple as copying it to the ProDOS 8 directory of the
239 program to load under name <program>.SYSTEM as a system program. For
240 example the program <tt/MYPROG/ is loaded by <tt/MYPROG.SYSTEM/.
245 If the cc65 program can be successfully linked as system program using the linker
246 configuration <ref id="apple-sys-cfg" name="apple2enh-system.cfg">, but
247 uses the heap either explicitly or implicitly (i.e. by loading a driver) then
248 the memory from $800 to $2000 can be added to the heap by calling
249 <tt/_heapadd ((void *) 0x0800, 0x1800);/ at the beginning of <tt/main()/.
252 <sect1>ProDOS 8 I/O buffers<p>
254 ProDOS 8 requires for every open file a page-aligned 1 KB I/O buffer. By default
255 these buffers are allocated by the cc65 runtime system on the heap using
256 <tt/posix_memalign()/. While this is generally the best solution it means quite
257 some overhead for (especially rather small) cc65 programs which do open files
258 but don't make use of the heap otherwise.
260 The apple2enh package comes with the alternative ProDOS 8 I/O buffer allocation
261 module <tt/apple2enh-iobuf-0800.o/ which uses the memory between $800 and
262 the program start address for the 1 KB I/O buffers. For system programs (with
263 start address $2000) this results in up to 6 I/O buffers and thus up to 6
264 concurrently open files.
266 While using <tt/_heapadd()/ as described in the section above together with the
267 default I/O buffer allocation basically yields the same placement of I/O buffers
268 in memory the primary benefit of <tt/apple2enh-iobuf-0800.o/ is a reduction in code
269 size - and thus program file size - of more than 1400 bytes.
271 Using <tt/apple2enh-iobuf-0800.o/ is as simple as placing it on the linker command
275 cl65 -t apple2enh -C apple2enh-system.cfg myprog.c apple2enh-iobuf-0800.o
280 <sect>Platform specific header files<p>
282 Programs containing enhanced Apple //e specific code may use the
283 <tt/apple2enh.h/ header file.
286 <sect1>Enhanced Apple //e specific functions<p>
288 The functions listed below are special for the enhanced Apple //e. See
289 the <url url="funcref.html" name="function reference"> for declaration and
297 <item>rebootafterexit
298 <item>ser_apple2_slot
306 <sect1>Hardware access<p>
308 There's currently no support for direct hardware access. This does not mean
309 you cannot do it, it just means that there's no help.
313 <sect>Loadable drivers<p>
315 The names in the parentheses denote the symbols to be used for static linking of the drivers.
318 <sect1>Graphics drivers<p>
322 <tag><tt/a2e.lo.tgi (a2e_lo_tgi)/</tag>
323 This driver features a resolution of 40×48 with 16 colors.
325 The function <tt/tgi_apple2_mix()/ allows to activate 4 lines of text. The
326 function clears the corresponding area at the bottom of the screen.
328 <tag><tt/a2e.hi.tgi (a2e_hi_tgi)/</tag>
329 This driver features a resolution of 280×192 with 8 colors and two
330 hires pages. Note that programs using this driver will have to be linked
331 with <tt/--start-addr $4000/ to reserve the first hires page or with
332 <tt/--start-addr $6000/ to reserve both hires pages.
334 Note that the second hires page is only available if the text display is not in
335 80 column mode. This can be asserted by calling <tt/videomode (VIDEOMODE_40COL);/
336 before installing the driver.
338 The function <tt/tgi_apple2_mix()/ allows to activate 4 lines of text. The
339 function doesn't clear the corresponding area at the bottom of the screen.
341 In memory constrained situations the memory from $803 to $1FFF
342 can be made available to a program by calling <tt/_heapadd ((void *) 0x0803, 0x17FD);/
343 at the beginning of <tt/main()/. Doing so is beneficial even if the program
344 doesn't use the the heap explicitly because loading the driver (and in fact
345 already opening the driver file) uses the heap implicitly.
350 <sect1>Extended memory drivers<p>
354 <tag><tt/a2e.auxmem.emd (a2e_auxmem_emd)/</tag>
355 Gives access to 47.5 KB RAM (190 pages of 256 bytes each) on an Extended
358 Note that this driver doesn't check for the actual existence of the memory
359 and that it doesn't check for ProDOS 8 RAM disk content!
364 <sect1>Joystick drivers<p>
368 <tag><tt/a2e.stdjoy.joy (a2e_stdjoy_joy)/</tag>
369 Supports up to two standard analog joysticks connected to the game port of
370 the enhanced Apple //e.
375 <sect1>Mouse drivers<p>
379 <tag><tt/a2e.stdmou.mou (a2e_stdmou_mou)/</tag>
380 Driver for the AppleMouse II Card. Searches all Apple II slots
381 for an AppleMouse II Card compatible firmware. The default bounding
382 box is [0..279,0..191].
384 Note that the enhanced Apple //e default mouse callbacks support
390 <sect1>RS232 device drivers<p>
394 <tag><tt/a2e.ssc.ser (a2e_ssc_ser)/</tag>
395 Driver for the Apple II Super Serial Card. Supports up to 19200 baud,
396 hardware flow control (RTS/CTS) and interrupt driven receives. Note
397 that because of the peculiarities of the 6551 chip transmits are not
398 interrupt driven, and the transceiver blocks if the receiver asserts
399 flow control because of a full buffer.
401 The driver defaults to slot 2. Call <tt/ser_apple2_slot()/ prior to
402 <tt/ser_open()/ in order to select a different slot. <tt/ser_apple2_slot()/
403 succeeds for all Apple II slots, but <tt/ser_open()/ fails with
404 <tt/SER_ERR_NO_DEVICE/ if there's no SSC firmware found in the selected slot.
415 Although the standard binaries generated by the linker for the enhanced Apple //e
416 generally run both on DOS 3.3 (with Applesoft BASIC) and on ProDOS 8 (with
417 BASIC.SYSTEM) there are some limitations for DOS 3.3:
421 <tag>Disk File I/O</tag>
422 There's no disk file I/O support. Any attempt to use it yields an error with
423 <tt/errno/ set to <tt/ENOSYS/. This implicitly means that loadable drivers
424 are in general not functional as they depend on disk file I/O. Therefore the statically
425 linked drivers have to be used instead.
428 There's no <tt/interruptor/ support. Any attempt to use it yields the message
429 'Failed to alloc interrupt' on program startup. This implicitly means that
430 <tt/a2e.stdmou.mou/ and <tt/a2e.ssc.ser/ are not functional as they depend on
436 <sect1>Direct console I/O<p>
441 The enhanced Apple //e has no color text mode. Therefore the functions
442 textcolor(), bgcolor() and bordercolor() have no effect.
445 The enhanced Apple //e has no hardware cursor. Therefore the function
446 cursor() has no effect.
455 <sect1>Passing arguments to the program<p>
457 Command line arguments can be passed to <tt/main()/ after BLOAD. Since this is not
458 supported by BASIC, the following syntax was chosen:
461 ]CALL2051:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
465 <item>Arguments are separated by spaces.
466 <item>Arguments may be quoted.
467 <item>Leading and trailing spaces around an argument are ignored. Spaces within
468 a quoted argument are allowed.
469 <item>The first argument passed to <tt/main/ is the program name.
470 <item>A maximum number of 10 arguments (including the program name) are
475 <sect1>Function keys<p>
477 These are defined to be OpenApple + number key.
482 The runtime for the enhanced Apple //e uses routines marked as
483 <tt/.INTERRUPTOR/ for ProDOS 8 interrupt handlers. Such routines must be
484 written as simple machine language subroutines and will be called
485 automatically by the interrupt handler code when they are linked into a
486 program. See the discussion of the <tt/.CONDES/ feature in the <url
487 url="ca65.html" name="assembler manual">.
495 The function <url url="dio.html#s1" name="dio_open()"> has the single
496 parameter <tt/device/ to identify the device to be opened. Therefore an
497 Apple II slot and drive pair is mapped to that <tt/drive_id/ according
501 device = slot + (drive - 1) * 8
504 so that for example slot 6 drive 2 is mapped to <tt/device/ 14.
507 The function <url url="dio.html#s3" name="dio_query_sectcount()"> returns
508 the correct sector count for all ProDOS 8 disks. However for any non-ProDOS 8
509 disk it simply always returns 280 (which is only correct for a 140 KB disk).
510 This condition is indicated by the <tt/_oserror/ value 82.
518 This software is provided 'as-is', without any expressed or implied
519 warranty. In no event will the authors be held liable for any damages
520 arising from the use of this software.
522 Permission is granted to anyone to use this software for any purpose,
523 including commercial applications, and to alter it and redistribute it
524 freely, subject to the following restrictions:
527 <item> The origin of this software must not be misrepresented; you must not
528 claim that you wrote the original software. If you use this software
529 in a product, an acknowledgment in the product documentation would be
530 appreciated but is not required.
531 <item> Altered source versions must be plainly marked as such, and must not
532 be misrepresented as being the original software.
533 <item> This notice may not be removed or altered from any source