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. The BASIC ROM is disabled, which gives a usable memory
45 range of $0800 - $CFFF. This means that kernal entry points may
46 be called directly, but using the BASIC ROM is not possible without additional
53 The text screen is located at $400 (as in the standard setup).
56 The C runtime stack is located at $CFFF and growing downwards.
61 <sect>Platform specific header files<p>
63 Programs containing C64 specific code may use the <tt/c64.h/ or <tt/cbm.h/
64 header files. Using the later may be an option when writing code for more than
65 one CBM platform, since it includes <tt/c64.h/ and declares several functions
66 common to all CBM platforms.
69 <sect1>C64 specific functions<p>
71 The functions listed below are special for the C64. See the <htmlurl
72 url="funcref.html" name="function reference"> for declaration and usage.
79 <sect1>CBM specific functions<p>
81 Some functions are available for all (or at least most) of the Commodore
82 machines. See the <htmlurl url="funcref.html" name="function reference"> for
83 declaration and usage.
111 <sect1>Hardware access<p>
113 The following pseudo variables declared in the <tt/c64.h/ header file do allow
114 access to hardware located in the address space. Some variables are
115 structures, accessing the struct fields will access the chip registers.
120 The <tt/VIC/ structure allows access to the VIC II (the graphics
121 controller). See the <tt/_vic2.h/ header file located in the include
122 directory for the declaration of the structure.
125 The <tt/SID/ structure allows access to the SID (the sound interface
126 device). See the <tt/_sid.h/ header file located in the include directory
127 for the declaration of the structure.
129 <tag><tt/CIA1, CIA2/</tag>
130 Access to the two CIA (complex interface adapater) chips is available via
131 the <tt/CIA1/ and <tt/CIA2/ variables. The structure behind these variables
132 is explained in <tt/_cia.h/.
134 <tag><tt/COLOR_RAM/</tag>
135 A character array that mirrors the color RAM of the C64 at $D800.
141 <sect>Loadable drivers<p>
143 <sect1>Graphics drivers<p>
145 All available graphics drivers for the TGI interface will use the space below
146 the I/O area and kernal ROM, so you can have hires graphics in the standard
147 setup without any memory loss or need for a changed configuration.
150 <tag><tt/c64-hi.tgi/</tag>
151 This driver features a resolution of 320*200 with two colors and an
152 adjustable palette (that means that the two colors can be choosen out of a
153 palette of the 16 C64 colors).
157 <sect1>Extended memory drivers<p>
161 <tag><tt/c64-georam.emd/</tag>
162 A driver for the GeoRam cartridge. The driver will always assume 2048 pages
165 <tag><tt/c64-ram.emd/</tag>
166 A driver for the hidden RAM below the I/O area and kernal ROM. Supports 48
167 256 byte pages. Please note that this driver is incompatible with any of the
170 <tag><tt/c64-ramcart.emd/</tag>
171 A driver for the RamCart 64/128. Will test the hardware for the available
174 <tag><tt/c64-reu.emd/</tag>
175 A driver for the CBM REUs. The driver will determine from the connected REU
176 if it supports 128KB of RAM or more. In the latter case, 256KB are assumed,
177 but since there are no range checks, the application can use more memory if
178 it has better knowledge about the hardware than the driver.
180 <tag><tt/c64-vdc.emd/</tag>
181 A driver for the VDC memory of the C128. Can be used if the program is
182 running in C64 mode of the C128. Autodetects the amount of memory available
183 (16 or 64K) and offers 64 or 256 pages of 256 bytes each.
188 <sect1>Joystick drivers<p>
192 <tag><tt/c64-stdjoy.joy/</tag>
193 Supports up to two standard joysticks connected to the joysticks port of
200 <sect1>Mouse drivers<p>
202 Currently no drivers available (in fact, the API for loadable mouse drivers
206 <sect1>RS232 device drivers<p>
210 <tag><tt/c64-swlink.ser/</tag>
211 Driver for the SwiftLink cartridge. Supports up to 38400 baud, hardware flow
212 control (RTS/CTS) and interrupt driven receives.
223 <sect>Bugs/Feedback<p>
225 If you have problems using the library, if you find any bugs, or if you're
226 doing something interesting with it, I would be glad to hear from you. Feel
227 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
228 name="uz@cc65.org">).
234 This software is provided 'as-is', without any expressed or implied
235 warranty. In no event will the authors be held liable for any damages
236 arising from the use of this software.
238 Permission is granted to anyone to use this software for any purpose,
239 including commercial applications, and to alter it and redistribute it
240 freely, subject to the following restrictions:
243 <item> The origin of this software must not be misrepresented; you must not
244 claim that you wrote the original software. If you use this software
245 in a product, an acknowledgment in the product documentation would be
246 appreciated but is not required.
247 <item> Altered source versions must be plainly marked as such, and must not
248 be misrepresented as being the original software.
249 <item> This notice may not be removed or altered from any source