--- /dev/null
+<!doctype linuxdoc system>
+
+<article>
+
+<title>C128 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 C128 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 C128 runtime system as it comes with the
+cc65 C compiler. It describes the memory layout, C128 specific header files,
+available drivers, and any pitfalls specific to that platform.
+
+Please note that C128 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 C128 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 ROM enabled. Note that this is a non standard memory layout, and that
+there is no "memory configuration index" for this layout. This means that
+special case has to be taken when changing the configuration, or calling any
+code that does this. The memory configuration register at $FF00 should
+be saved and restored instead of relying on the memory configuration index
+stored in the zero page.
+
+The setup gives a usable memory range of $1C00 - $CFFF. Having
+just the kernal ROM mapped in means, that kernal entry points may be called
+directly, but using the BASIC ROM is not possible without additional code.
+
+Special locations:
+
+<descrip>
+ <tag/Text screen/
+ The text screen is located at $400 (as in the standard setup).
+
+ <tag/Stack/
+ The C runtime stack is located at $CFFF 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 C128 specific code may use the <tt/c128.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/c128.h/ and declares several functions
+common to all CBM platforms.
+
+
+<sect1>C128 specific functions<p>
+
+The functions listed below are special for the C128. See the <htmlurl
+url="funcref.html" name="function reference"> for declaration and usage.
+
+<itemize>
+<item>toggle_videomode
+<item>c64mode
+<item>fast
+<item>slow
+</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/c128.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 II (the graphics
+ controller). See the <tt/_vic2.h/ header file located in the include
+ directory for the declaration of the structure.
+
+ <tag><tt/SID/</tag>
+ The <tt/SID/ structure allows access to the SID (the sound interface
+ device). See the <tt/_sid.h/ header file located in the include directory
+ for the declaration of the structure.
+
+ <tag><tt/VDC/</tag>
+ The <tt/VDC/ structure allows access to the VDC (the video display
+ controller). See the <tt/_vdc.h/ header file located in the include
+ directory for the declaration of the structure.
+
+ <tag><tt/CIA1, CIA2/</tag>
+ Access to the two CIA (complex interface adapater) chips is available via
+ the <tt/CIA1/ and <tt/CIA2/ variables. The structure behind these variables
+ is explained in <tt/_cia.h/.
+
+ <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>
+
+Note: The graphics drivers for the VDC are incompatible with the extended
+memory drivers using the VDC memory!
+
+<descrip>
+ <tag><tt/c128-vdc.tgi/</tag>
+ This driver uses the 80 column display and features a resolution of 640*200
+ with two colors and an adjustable palette (that means that the two colors
+ can be choosen out of the 16 VDC colors).
+
+ <tag><tt/c128-vdc2.tgi/</tag>
+ This driver uses the 80 column display and features a resolution of 640*480
+ with two colors and an adjustable palette (that means that the two colors
+ can be choosen out of the 16 VDC colors).
+</descrip><p>
+
+
+<sect1>Extended memory drivers<p>
+
+<descrip>
+
+ <tag><tt/c128-georam.emd/</tag>
+ A driver for the GeoRam cartridge. The driver will always assume 2048 pages
+ of 256 bytes each. There are no checks, so if your program knows better,
+ just go ahead.
+
+ <tag><tt/c128-ram.emd/</tag>
+ An extended memory driver for the RAM in page 1. The common memory area is
+ excluded, so this driver supports 251 pages of 256 bytes each.
+
+ <tag><tt/c128-ramcart.emd/</tag>
+ A driver for the RamCart 64/128. Will test the hardware for the available
+ RAM.
+
+ <tag><tt/c128-reu.emd/</tag>
+ A driver for the CBM REUs. The driver will determine from the connected REU
+ if it supports 128KB of RAM or more. In the latter case, 256KB are assumed,
+ but since there are no range checks, the application can use more memory if
+ it has better knowledge about the hardware than the driver.
+
+ <tag><tt/c128-vdc.emd/</tag>
+ A driver for the VDC memory of the C128. Autodetects the amount of memory
+ available (16 or 64K) and offers 64 or 256 pages of 256 bytes each. Note:
+ This driver is incompatible with any of the graphics drivers using the VDC!
+
+</descrip><p>
+
+
+<sect1>Joystick drivers<p>
+
+<descrip>
+
+ <tag><tt/c128-ptvjoy.joy/</tag>
+ Driver for the Protovision 4-player adapter. See
+ <htmlurl url="http://www.protovision-online.de/hardw/hardwstart.htm"
+ name="http://www.protovision-online.de/hardw/hardwstart.htm"> for prices
+ and building instructions. Up to four joysticks are supported.
+
+ <tag><tt/c128-stdjoy.joy/</tag>
+ Supports up to two joysticks connected to the standard joysticks port of
+ the C128.
+
+</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/c128-swlink.ser/</tag>
+ Driver for the SwiftLink cartridge. Supports up to 38400 baud, hardware flow
+ control (RTS/CTS) and interrupt driven receives. Note that because of the
+ peculiarities of the 6551 chip together with the use of the NMI, transmits
+ are not interrupt driven, and the transceiver blocks if the receiver asserts
+ flow control because of a full buffer.
+
+ The driver uses the RS232 variables and buffers of the kernal (buffers at
+ $C00 and $D00).
+
+</descrip><p>
+
+
+
+<sect>Other hints<p>
+
+<sect1>Passing arguments to the program<p>
+
+Command line argument passing is currently not supported for the C128.
+
+
+<sect1>Interrupts<p>
+
+The runtime for the C128 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