--- /dev/null
+<!doctype linuxdoc system>
+
+<article>
+
+<title>Atari Lynx specific information for cc65
+<author>Karri Kaksonen, <htmlurl url="mailto:karri@sipo.fi" name="karri@sipo.fi">
+Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
+<date>2011-04-01
+
+<abstract>
+An overview over the Atari Lynx 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 Atari Lynx runtime system as it comes
+with the cc65 C compiler. It describes the memory layout, Lynx specific header
+files, available drivers, and any pitfalls specific to that platform.
+
+Please note that Lynx 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>Building your first Hello World application<p>
+
+Here is a small traditional Hello World program for the Atari Lynx.
+
+<tscreen><verb>
+#include <lynx.h>
+#include <tgi.h>
+#include <6502.h>
+
+void main(void) {
+ tgi_install(tgi_static_stddrv);
+ tgi_init();
+ CLI();
+ while (tgi_busy())
+ ;
+ tgi_clear();
+ tgi_setcolor(COLOR_GREEN);
+ tgi_outtextxy(0, 0, "Hello World");
+ tgi_updatedisplay();
+ while (1)
+ ;
+}
+</verb></tscreen>
+
+The lynx.h contains all kind of system dependent things.
+
+The tgi.h contains the graphics driver functions.
+
+The 6502.h is needed for executing the CLI() command.
+
+As the Atari Lynx does not have ASCII characters available you need to use
+the Tiny Graphics Interface library for producing letters on the screen.
+
+The cc65 compiler suite has a graphics library called "Tiny Graphics
+Interface". This interface has some relocatable code. In order to use this
+in your own program you need to load it at run time.
+
+Unfortunately the Lynx does not have a disk drive from where to load it.
+Therefore you must already load it at compile time. The easiest way is to
+automatically link it in statically from the Lynx C library.
+
+<tscreen><verb>
+cl65 -t lynx -o game.lnx main.c
+</verb></tscreen>
+
+This will create a bootable cart image called game.lnx
+
+
+<sect>Binary format<p>
+
+The standard binary output format generated by the linker for the Lynx target
+is a cart image. By specifying the config file lynx-bll.cfg the linker will
+generate BLL download compatible binary files.
+
+It is of course possible to change this behaviour by using a modified startup
+file and linker config.
+
+The bootloader used in the cc65 lynx library uses a very minimal bootloader
+that does not check the cart or show a title screen.
+
+The advantage of this bootloader is that it allows creation of cart images to
+many common formats.
+
+Cart sizes
+<tscreen><verb>
+Block size Rom size Description
+512 bytes 128k Standard old games like Warbirds
+1024 bytes 256k Most common format for homebrew. Also newer games like Lemmings
+2048 bytes 512k Largest games like EOTB
+</verb></tscreen>
+
+<sect>Memory layout<p>
+
+cc65 generated programs with the default setup run with the I/O area and the
+kernal enabled, which gives a usable memory range of $200 - $C037.
+
+Special locations:
+<tscreen><verb>
+ 0000 - 00FF Zero page
+ 0100 - 01FF Machine stack
+
+ A058 - C037 Collision buffer
+ C038 - E017 Screen buffer 1
+ E018 - FFF7 Screen buffer 0
+ FFF8 - FFFF Hardware vectors
+</verb></tscreen>
+
+<descrip>
+ <tag/Text screen/
+ No conio support is currently available for the Lynx.
+
+ <tag/Keyboard/
+ The Lynx "flabode" keys, Opt 1, Pause and Opt 2 are implemented using the
+ conio interface. The only characters the keyboard is able to produce are
+ 'R' for Restart (Opt 1 + Pause), 'F' for flip (Opt 2 + Pause),
+ 'P' for pause, '1' for Opt 1, '2' for Opt 2, '3' for Opt 1 + Opt 2 and
+ '?' for all keys down at the same time.
+
+ <tag/Stack/
+ The C runtime stack is located at $C037 (or $A057 if collision
+ detection is enabled) and growing downwards.
+
+ <tag/Heap/
+ The C heap is located at the end of the program and grows towards the C
+ runtime stack.
+
+ <tag/Screen/
+ The collision detection screen is at $A058 if it is enabled. The
+ double buffered screens are at $C038 and $E018.
+
+</descrip><p>
+
+
+
+<sect>Platform specific header files<p>
+
+Programs containing Lynx specific code may use the <tt/lynx.h/ header file.
+
+
+<sect1>Lynx specific functions<p>
+
+<itemize>
+<item>lynx_eeprom_erase
+<item>lynx_eeprom_read
+<item>lynx_eeprom_write
+<item>lynx_eeread
+<item>lynx_eewrite
+<item>lynx_exec
+<item>lynx_load
+</itemize>
+
+
+
+<sect1>Hardware access<p>
+
+The following pseudo variables declared in the <tt/lynx.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/MIKEY/</tag>
+ The <tt/MIKEY/ structure allows access to MIKEY chip. See the <tt/_mikey.h/
+ header file located in the include directory for the declaration of the
+ structure.
+
+ <tag><tt/SUZY/</tag>
+ The <tt/SUZY/ structure allows access to SUZY chip. See the <tt/_suzy.h/
+ header file located in the include directory for the declaration of the
+ structure.
+
+</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>
+
+<descrip>
+
+ <tag><tt/lynx-160-102-16.tgi (lynx_160_102_16)/</tag>
+ A TGI driver for the standard graphics mode (160×102 in 16 colors).
+
+ The TGI driver is implemented as an interrupt driven dual buffering device.
+ To use it as a single-buffer device set draw page and view page to the same
+ value 0 or 1;
+
+ The TGI driver has a few Lynx-specific extensions.
+
+ Calling tgi_sprite(spr) or tgi_ioctl(0, spr) will display a standard Lynx
+ sprite on screen.
+
+ Calling tgi_flip() or tgi_ioctl(1, 0) will do a flip screen.
+
+ Calling tgi_setbgcolor(bgcolor) or tgi_ioctl(2, bgindex) will set the text
+ background color to the index defined by bgindex. If bgindex is 0 then the
+ background color is transparent.
+
+ To set the framerate of the display hardware call tgi_setframerate(rate) or
+ tgi_ioctl(3, rate). The supported framerates are 50, 60 and 75 frames per
+ second. Actually there is no real reason to use anything else than 75 frames
+ per second.
+
+ To check if the drawing engine is busy with the previous swap you can
+ call tgi_busy or tgi_ioctl(4, 0). It returns 0 if idle and 1 if busy
+
+ To update displays you can call tgi_updatedisplay() or tgi_ioctl(4, 1) it
+ will wait for the next VBL interrupt and set the draw buffer to the
+ view buffer. The draw buffer is also changed to (drawbuffer xor 1).
+
+ You can also enable or disable collision detection by a call to
+ tgi_setcollisiondetection(active) or tgi_ioctl(5, active). The collision
+ result is located before the sprite structure by default in this driver.
+
+ In order to reserve memory for the collision detection buffer you need to
+ specify lynx-coll.cfg as the configuration file to the linker.
+
+</descrip><p>
+
+
+<sect1>Extended memory drivers<p>
+
+No extended memory drivers are currently available for the Lynx.
+
+
+<sect1>Joystick drivers<p>
+
+<descrip>
+
+ <tag><tt/lynx-stdjoy.joy (lynx_stdjoy)/</tag>
+ A joystick driver for the standard buttons.
+
+</descrip><p>
+
+
+<sect1>Mouse drivers<p>
+
+No mouse drivers are currently available for the Lynx.
+
+
+<sect1>RS232 device drivers<p>
+
+<descrip>
+
+ <tag><tt/lynx-comlynx.ser (lynx_comlynx)/</tag>
+ A serial driver for the ComLynx port.
+
+ The ComLynx port has Tx and Rx wired together. Every byte is sent
+ to all connected Lynxes. Only one Lynx can send at a time. There is no
+ protocol created for communication. You are on your own.
+
+ If the Lynx returns framing error then it is likely that another Lynx is
+ sending data at the same time.
+
+ The Lynx can also send a break and receive a break. The Lynx break is
+ recognized if the bit is down for 24 bit cycles or more.
+
+ To send a break you just set the break bit. The length of the break depends
+ on how long this bit is down.
+
+ The driver supports the baudrates:
+ <itemize>
+ <item>62500
+ <item>31250
+ <item>9600
+ <item>7200
+ <item>4800
+ <item>3600
+ <item>2400
+ <item>1800
+ <item>1200
+ <item>600
+ <item>300
+ <item>150
+ <item>134.5
+ <item>110
+ <item>75
+ </itemize>
+ The parity bit supports MARK and SPACE. It also supports EVEN and ODD parity
+ but the parity bit is included in the calculation. Most of us don't want it
+ this way. But there is nothing we can do about it.
+
+ The Lynx hardware will always check parity on incoming traffic. Currently
+ the driver cannot receive data from standard PC's due to this parity bug.
+ For working with Lynx to Lynx communication use EVEN parity.
+
+ To send data to standard PC's use MARK or SPACE as parity setting.
+
+ There is always only one stop bit. And the data length is always 8 bits.
+
+ We have no handshaking available. Even software handshake is impossible
+ as ComLynx has only one wire for the data.
+
+ Both transmit and receive are interrupt driven.
+
+</descrip><p>
+
+
+<sect>Limitations<p>
+
+
+
+<sect>Cart access<p>
+
+At this point in time there is no support for the cart filesystem yet. I have
+a <tt/lynx-cart-demo/ example project that uses an interrupt driven display,
+has support for the cart filesystem and an abcmusic sound module.
+
+At some point in time we may find a way to rewrite these to fit the way the
+cc65 drivers require. But for the time being you can create less portable
+applications using these Lynx specific modules in <tt/lynx-cart-demo/.
+
+
+<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 / blobdiff