--- /dev/null
+<!doctype linuxdoc system>
+
+<article>
+
+<title>Commodore Plus/4 specific information for cc65
+<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
+<date>2003-12-14
+
+<abstract>
+An overview over the Plus/4 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 Plus/4 runtime system as it comes with the
+cc65 C compiler. It describes the memory layout, Plus/4 specific header files,
+available drivers, and any pitfalls specific to that platform.
+
+Please note that Plus/4 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.
+
+Since the Plus/4 and the Commodore 16/116 are almost identical (the latter are
+missing the 6551 ACIA and do only have 16KB of memory), the <htmlurl
+url="c16.html" name="C16 documentation"> is also worth a look. The difference
+between both targets is that the Plus/4 runtime uses banking to support full
+64K RAM, while the C16 does not use banking and supports up to 32K RAM.
+Because banking is not needed, most C16 programs will be somewhat smaller than
+the same program compiled for the Plus/4. However, programs compiled for the
+C16 will always run on the Plus/4, while the reverse is not necessarily true.
+
+
+<sect>Binary format<p>
+
+The standard binary output format generated by the linker for the Plus/4
+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 kernal and basic
+banked out. This gives a usable memory range of $1000 - $FD00.
+Having the kernal and basic ROMs banked out means, that no ROM entry points
+may be called directly from user code.
+
+Special locations:
+
+<descrip>
+ <tag/Text screen/
+ The text screen is located at $C00 (as in the standard setup).
+
+ <tag/Color RAM/
+ The color RAM is located at $800 (standard location).
+
+ <tag/Stack/
+ The C runtime stack is located at $FCFF 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 Plus/4 specific code may use the <tt/plus4.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/plus4.h/ and declares several functions
+common to all CBM platforms.
+
+Please note that most of the header file declarations from the <tt/plus4.h/
+header file are shared between the C16 and Plus/4 configurations. For this
+reason, most of it is located in a common header file named <tt/cbm264.h/.
+
+
+
+<sect1>Plus/4 specific functions<p>
+
+There are currently no special Plus/4 functions.
+
+
+<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/plus4.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/TED/</tag>
+ The <tt/TED/ structure allows access to the TED chip. See the
+ <tt/_ted.h/ header file located in the include directory for the
+ declaration of the structure.
+
+ <tag><tt/COLOR_RAM/</tag>
+ A character array that mirrors the color RAM of the C64 at $D800.
+
+</descrip><p>
+
+
+
+<sect>Loadable drivers<p>
+
+<sect1>Graphics drivers<p>
+
+No graphics drivers are currently available for the Plus/4.
+
+
+<sect1>Extended memory drivers<p>
+
+No extended memory drivers are currently available for the Plus/4.
+
+
+
+<sect1>Joystick drivers<p>
+
+<descrip>
+
+ <tag><tt/plus4-stdjoy.joy/</tag>
+ Supports up to two joysticks connected to the standard joysticks port of
+ the Plus/4.
+
+</descrip><p>
+
+
+
+<sect1>Mouse drivers<p>
+
+Currently no drivers available (in fact, the API for loadable mouse drivers
+does not exist).
+
+
+<sect1>RS232 device drivers<p>
+
+<descrip>
+
+ <tag><tt/plus4-stdser.ser/</tag>
+ Driver for the 6551 ACIA chip built into the Plus/4 Supports up to 19200
+ baud, hardware flow control (RTS/CTS) and interrupt driven receives. Note
+ that because of the peculiarities of the 6551 chip transmits are not
+ interrupt driven, and the transceiver blocks if the receiver asserts flow
+ control because of a full buffer.
+
+ Note that you need an adapter to use the builtin port, since the output
+ levels available at the user port don't follow the RS232 standard.
+
+</descrip><p>
+
+
+
+<sect>Other hints<p>
+
+<sect1>Passing arguments to the program<p>
+
+Command line argument passing is currently not supported for the Plus/4.
+
+
+<sect1>Interrupts<p>
+
+The runtime for the Plus/4 uses routines marked as <tt/.CONDES/ type 2 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 <htmlurl url="ca65.html" name="assembler manual">.
+
+
+
+<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