1 <!doctype linuxdoc system>
5 <title>c64 specific information for cc65
6 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
10 An overview over the C64 runtime system as it is implemented for the cc65 C
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 This file contains an overview of the C64 runtime system as it comes with the
22 cc65 C compiler. It describes the memory layout, C64 specific header files,
23 available drivers, and any pitfalls specific to that platform.
25 Please note that C64 specific functions are just mentioned here, they are
26 described in detail in the separate <htmlurl url="funcref.html" name="function
27 reference">. Even functions marked as "platform dependent" may be available on
28 more than one platform. Please see the function reference for more
32 <sect>Binary format<p>
34 The standard binary output format generated by the linker for the C64 target
35 is a machine language program with a one line BASIC stub. This means that a
36 program can be loaded as BASIC program and started with RUN. It is of course
37 possible to change this behaviour by using a modified startup file and linker
41 <sect>Memory layout<p>
43 cc65 generated programs with the default setup run with the I/O area and the
44 kernal ROM enabled (memory under the kernal may be used for graphics or as
45 extended memory - see the sections about graphics and extended memory
46 drivers). The BASIC ROM is disabled, which gives a usable memory range of
47 $0800 - $CFFF. This means that kernal entry points may be called
48 directly, but using the BASIC ROM is not possible without additional code.
54 The text screen is located at $400 (as in the standard setup).
57 The C runtime stack is located at $CFFF and growing downwards.
60 The C heap is located at the end of the program and grows towards the C
67 <sect>Platform specific header files<p>
69 Programs containing C64 specific code may use the <tt/c64.h/ or <tt/cbm.h/
70 header files. Using the later may be an option when writing code for more than
71 one CBM platform, since it includes <tt/c64.h/ and declares several functions
72 common to all CBM platforms.
75 <sect1>C64 specific functions<p>
77 The functions listed below are special for the C64. See the <htmlurl
78 url="funcref.html" name="function reference"> for declaration and usage.
85 <sect1>CBM specific functions<p>
87 Some functions are available for all (or at least most) of the Commodore
88 machines. See the <htmlurl url="funcref.html" name="function reference"> for
89 declaration and usage.
117 <sect1>Hardware access<p>
119 The following pseudo variables declared in the <tt/c64.h/ header file do allow
120 access to hardware located in the address space. Some variables are
121 structures, accessing the struct fields will access the chip registers.
126 The <tt/VIC/ structure allows access to the VIC II (the graphics
127 controller). See the <tt/_vic2.h/ header file located in the include
128 directory for the declaration of the structure.
131 The <tt/SID/ structure allows access to the SID (the sound interface
132 device). See the <tt/_sid.h/ header file located in the include directory
133 for the declaration of the structure.
135 <tag><tt/CIA1, CIA2/</tag>
136 Access to the two CIA (complex interface adapater) chips is available via
137 the <tt/CIA1/ and <tt/CIA2/ variables. The structure behind these variables
138 is explained in <tt/_cia.h/.
140 <tag><tt/COLOR_RAM/</tag>
141 A character array that mirrors the color RAM of the C64 at $D800.
147 <sect>Loadable drivers<p>
149 <sect1>Graphics drivers<p>
151 All available graphics drivers for the TGI interface will use the space below
152 the I/O area and kernal ROM, so you can have hires graphics in the standard
153 setup without any memory loss or need for a changed configuration.
156 <tag><tt/c64-hi.tgi/</tag>
157 This driver features a resolution of 320*200 with two colors and an
158 adjustable palette (that means that the two colors can be choosen out of a
159 palette of the 16 C64 colors).
163 <sect1>Extended memory drivers<p>
167 <tag><tt/c64-georam.emd/</tag>
168 A driver for the GeoRam cartridge. The driver will always assume 2048 pages
171 <tag><tt/c64-ram.emd/</tag>
172 A driver for the hidden RAM below the I/O area and kernal ROM. Supports 48
173 256 byte pages. Please note that this driver is incompatible with any of the
176 <tag><tt/c64-ramcart.emd/</tag>
177 A driver for the RamCart 64/128. Will test the hardware for the available
180 <tag><tt/c64-reu.emd/</tag>
181 A driver for the CBM REUs. The driver will determine from the connected REU
182 if it supports 128KB of RAM or more. In the latter case, 256KB are assumed,
183 but since there are no range checks, the application can use more memory if
184 it has better knowledge about the hardware than the driver.
186 <tag><tt/c64-vdc.emd/</tag>
187 A driver for the VDC memory of the C128. Can be used if the program is
188 running in C64 mode of the C128. Autodetects the amount of memory available
189 (16 or 64K) and offers 64 or 256 pages of 256 bytes each.
194 <sect1>Joystick drivers<p>
198 <tag><tt/c64-hitjoy.joy/</tag>
199 Driver for the Digital Excess & Hitmen adapter. See
200 <htmlurl url="http://www.digitalexcess.de/downloads/productions.php"
201 name="http://www.digitalexcess.de/downloads/productions.php"> on
202 instructions how to build one. Up to four joysticks are supported.
204 <tag><tt/c64-ptvjoy.joy/</tag>
205 Driver for the Protovision 4-player adapter. See
206 <htmlurl url="http://www.protovision-online.de/hardw/hardwstart.htm"
207 name="http://www.protovision-online.de/hardw/hardwstart.htm"> for prices
208 and building instructions. Up to four joysticks are supported.
210 <tag><tt/c64-stdjoy.joy/</tag>
211 Supports up to two standard joysticks connected to the joysticks port of
218 <sect1>Mouse drivers<p>
220 Currently no drivers available (in fact, the API for loadable mouse drivers
224 <sect1>RS232 device drivers<p>
228 <tag><tt/c64-swlink.ser/</tag>
229 Driver for the SwiftLink cartridge. Supports up to 38400 baud, hardware flow
230 control (RTS/CTS) and interrupt driven receives.
238 <sect1>Passing arguments to the program<p>
240 Command line arguments can be passed to <tt/main()/. Since this is not
241 supported by BASIC, the following syntax was choosen:
244 RUN:REM,ARG1," ARG2", ARG 3,, ARG5, ...
248 <item>Arguments are separated by commas.
249 <item>There must be a comma after the first <tt/REM/.
250 <item>Leading spaces are ignored; trailing spaces are included unless the
252 <item>The first argument passed to <tt/main/ is the program name.
257 <sect>Bugs/Feedback<p>
259 If you have problems using the library, if you find any bugs, or if you're
260 doing something interesting with it, I would be glad to hear from you. Feel
261 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
262 name="uz@cc65.org">).
268 This software is provided 'as-is', without any expressed or implied
269 warranty. In no event will the authors be held liable for any damages
270 arising from the use of this software.
272 Permission is granted to anyone to use this software for any purpose,
273 including commercial applications, and to alter it and redistribute it
274 freely, subject to the following restrictions:
277 <item> The origin of this software must not be misrepresented; you must not
278 claim that you wrote the original software. If you use this software
279 in a product, an acknowledgment in the product documentation would be
280 appreciated but is not required.
281 <item> Altered source versions must be plainly marked as such, and must not
282 be misrepresented as being the original software.
283 <item> This notice may not be removed or altered from any source