mirror of
https://github.com/cc65/cc65.git
synced 2024-06-07 07:29:33 +00:00
bb9aa7558f
Those tags have two attributes: "url=" and "name=". In the non-HTML output formats, <url> shows both fields, while <htmlurl> shows only the name field (as the HTML format always does.) Thus, the general rules are 1. If the two attributes are different, then use <url>. 2. If they are similar, then use <htmlurl>. 3. If they are the same, then consider using <url> without the "name=" attribute. (The reason for rules 2 and 3 is that the same text shouldn't be shown twice.) There can be exceptions. Example: "od65.sgml" has <htmlurl> because the URL would disturb the flow of a sentence.
265 lines
7.2 KiB
Plaintext
265 lines
7.2 KiB
Plaintext
<!doctype linuxdoc system>
|
|
|
|
<article>
|
|
|
|
<title>Commodore VIC20 (aka VC20) specific information for cc65
|
|
<author>
|
|
<url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
|
|
<url url="mailto:polluks@sdf.lonestar.org" name="Stefan A. Haubenthal">
|
|
<date>2014-04-12
|
|
|
|
<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 <url 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, which calls the
|
|
machine language part via SYS. 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 unexpanded memory
|
|
(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>
|
|
|
|
There are currently no special VIC20 functions.
|
|
|
|
|
|
|
|
<sect1>CBM-specific functions<p>
|
|
|
|
Some functions are available for all (or at least most) of the Commodore
|
|
machines. See the <url 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>
|
|
|
|
The names in the parentheses denote the symbols to be used for static linking of the drivers.
|
|
|
|
|
|
<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>
|
|
|
|
The default drivers, <tt/joy_stddrv (joy_static_stddrv)/, point to <tt/vic20-stdjoy.joy (vic20_stdjoy_joy)/.
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/vic20-stdjoy.joy (vic20_stdjoy_joy)/</tag>
|
|
Supports one standard joystick connected to the joysticks port of the VIC20.
|
|
|
|
<tag><tt/vic20-ptvjoy.joy (vic20_ptvjoy_joy)/</tag>
|
|
Driver for the Protovision 4-player adapter contributed by Groepaz. See
|
|
<url url="http://www.protovision-online.de/hardw/hardwstart.htm"> for prices and
|
|
building instructions. Up to three joysticks are supported.
|
|
|
|
</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>Escape code<p>
|
|
|
|
For an Esc, press CTRL and the <tt/[/ key.
|
|
|
|
|
|
<sect1>Passing arguments to the program<p>
|
|
|
|
Command-line arguments can be passed to <tt/main()/. Since that is not
|
|
supported directly 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.
|
|
|
|
|
|
<sect1>Using extended memory<p>
|
|
|
|
The extended memory at $A000 may be added to the heap by using the following
|
|
code:
|
|
|
|
<tscreen><verb>
|
|
/* Check for the existence of RAM */
|
|
if (PEEK(0xA000) == POKE(0xA000, PEEK(0xA000)+1)) {
|
|
/* Add it to the heap */
|
|
_heapadd ((void *) 0xA000, 0x2000);
|
|
}
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Interrupts<p>
|
|
|
|
The runtime for the VIC20 uses routines marked as <tt/.INTERRUPTOR/ for
|
|
interrupt handlers. Such routines must be written as simple machine language
|
|
subroutines and will be called automatically by the interrupt handler code
|
|
when they are linked into a program. See the discussion of the <tt/.CONDES/
|
|
feature in the <url url="ca65.html" name="assembler manual">.
|
|
|
|
|
|
|
|
<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>
|