--- /dev/null
+<!doctype linuxdoc system>
+
+<article>
+
+<title>Commodore VIC20 (aka VC20) specific information for cc65
+<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
+Stefan A. Haubenthal, <htmlurl url="mailto:polluks@sdf.lonestar.org" name="polluks@sdf.lonestar.org">
+<date>2004-09-13
+
+<abstract>
+An overview over the VIC20 runtime system as it is implemented for the cc65 C
+compiler.
+</abstract>
+
+<!-- Table of contents -->
+<toc>
+
+<!-- Begin the document -->
+
+<sect>Overview<p>
+
+This file contains an overview of the VIC20 runtime system as it comes with the
+cc65 C compiler. It describes the memory layout, VIC20 specific header files,
+available drivers, and any pitfalls specific to that platform.
+
+Please note that VIC20 specific functions are just mentioned here, they are
+described in detail in the separate <htmlurl url="funcref.html" name="function
+reference">. Even functions marked as "platform dependent" may be available on
+more than one platform. Please see the function reference for more
+information.
+
+
+<sect>Binary format<p>
+
+The standard binary output format generated by the linker for the VIC20 target
+is a machine language program with a one line BASIC stub. This means that a
+program can be loaded as BASIC program and started with RUN. It is of course
+possible to change this behaviour by using a modified startup file and linker
+config.
+
+
+<sect>Memory layout<p>
+
+cc65 generated programs with the default setup run with the I/O area and the
+kernal and BASIC ROM enabled (RAM at $A000 - $BFFF may be used
+for the heap), which gives a usable memory range of $1000 - $1DFF.
+All ROM entry points may be called directly without additional code.
+
+Special locations:
+
+<descrip>
+ <tag/Text screen/
+ The text screen is located at $1E00 (as in the standard setup).
+
+ <tag/Stack/
+ The C runtime stack is located at $1DFF and growing downwards.
+
+ <tag/Heap/
+ The C heap is located at the end of the program and grows towards the C
+ runtime stack.
+
+</descrip><p>
+
+
+
+<sect>Platform specific header files<p>
+
+Programs containing VIC20 specific code may use the <tt/vic20.h/ or <tt/cbm.h/
+header files. Using the later may be an option when writing code for more than
+one CBM platform, since it includes <tt/vic20.h/ and declares several functions
+common to all CBM platforms.
+
+
+<sect1>VIC20 specific functions<p>
+
+The functions listed below are special for the VIC20. See the <htmlurl
+url="funcref.html" name="function reference"> for declaration and usage.
+
+<itemize>
+<item>get_ostype
+</itemize>
+
+
+<sect1>CBM specific functions<p>
+
+Some functions are available for all (or at least most) of the Commodore
+machines. See the <htmlurl url="funcref.html" name="function reference"> for
+declaration and usage.
+
+<itemize>
+<item>cbm_close
+<item>cbm_closedir
+<item>cbm_k_setlfs
+<item>cbm_k_setnam
+<item>cbm_k_load
+<item>cbm_k_save
+<item>cbm_k_open
+<item>cbm_k_close
+<item>cbm_k_readst
+<item>cbm_k_chkin
+<item>cbm_k_ckout
+<item>cbm_k_basin
+<item>cbm_k_bsout
+<item>cbm_k_clrch
+<item>cbm_load
+<item>cbm_open
+<item>cbm_opendir
+<item>cbm_read
+<item>cbm_readdir
+<item>cbm_save
+<item>cbm_write
+<item>get_tv
+</itemize>
+
+
+<sect1>Hardware access<p>
+
+The following pseudo variables declared in the <tt/vic20.h/ header file do allow
+access to hardware located in the address space. Some variables are
+structures, accessing the struct fields will access the chip registers.
+
+<descrip>
+
+ <tag><tt/VIC/</tag>
+ The <tt/VIC/ structure allows access to the VIC (the graphics
+ controller). See the <tt/_vic.h/ header file located in the include
+ directory for the declaration of the structure.
+
+ <tag><tt/VIA1, VIA2/</tag>
+ Access to the two VIA (versatile interface adapter) chips is available via
+ the <tt/VIA1/ and <tt/VIA2/ variables. The structure behind these variables
+ is explained in <tt/_6522.h/.
+
+ <tag><tt/COLOR_RAM/</tag>
+ A character array that mirrors the color RAM of the VIC20 at $9600.
+
+</descrip><p>
+
+
+
+<sect>Loadable drivers<p>
+
+<sect1>Graphics drivers<p>
+
+No graphics drivers are currently available for the VIC20.
+
+
+<sect1>Extended memory drivers<p>
+
+No extended memory drivers are currently available for the VIC20.
+
+
+<sect1>Joystick drivers<p>
+
+<descrip>
+
+ <tag><tt/vic20-stdjoy.joy/</tag>
+ Supports one standard joystick connected to the joysticks port of the VIC20.
+
+</descrip><p>
+
+
+
+<sect1>Mouse drivers<p>
+
+No mouse drivers are currently available for the VIC20.
+
+
+<sect1>RS232 device drivers<p>
+
+No VIC1011 drivers are currently available for the VIC20.
+
+
+
+<sect>Limitations<p>
+
+
+
+<sect>Other hints<p>
+
+<sect1>Passing arguments to the program<p>
+
+Command line arguments can be passed to <tt/main()/. Since this is not
+supported by BASIC, the following syntax was chosen:
+
+<tscreen><verb>
+ RUN:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
+</verb></tscreen>
+
+<enum>
+<item>Arguments are separated by spaces.
+<item>Arguments may be quoted.
+<item>Leading and trailing spaces around an argument are ignored. Spaces within
+ a quoted argument are allowed.
+<item>The first argument passed to <tt/main/ is the program name.
+<item>A maximum number of 10 arguments (including the program name) are
+ supported.
+</enum>
+
+
+<sect1>Program return code<p>
+
+The program return code (low byte) is passed back to BASIC by use of the
+<tt/ST/ variable.
+
+
+
+
+<sect>Bugs/Feedback<p>
+
+If you have problems using the library, if you find any bugs, or if you're
+doing something interesting with it, I would be glad to hear from you. Feel
+free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
+name="uz@cc65.org">).
+
+
+
+<sect>License<p>
+
+This software is provided 'as-is', without any expressed or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+<enum>
+<item> The origin of this software must not be misrepresented; you must not
+ claim that you wrote the original software. If you use this software
+ in a product, an acknowledgment in the product documentation would be
+ appreciated but is not required.
+<item> Altered source versions must be plainly marked as such, and must not
+ be misrepresented as being the original software.
+<item> This notice may not be removed or altered from any source
+ distribution.
+</enum>
+
+</article>
+
+
+
projects / cc65 / commitdiff