1 <!doctype linuxdoc system>
5 <title>Atari Lynx specific information for cc65
6 <author>Karri Kaksonen, <htmlurl url="mailto:karri@sipo.fi" name="karri@sipo.fi">
7 Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
11 An overview over the Atari Lynx runtime system as it is implemented for the
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 This file contains an overview of the Atari Lynx runtime system as it comes
23 with the cc65 C compiler. It describes the memory layout, Lynx specific header
24 files, available drivers, and any pitfalls specific to that platform.
26 Please note that Lynx specific functions are just mentioned here, they are
27 described in detail in the separate <htmlurl url="funcref.html" name="function
28 reference">. Even functions marked as "platform dependent" may be available on
29 more than one platform. Please see the function reference for more
33 <sect>Building your first Hello World application<p>
35 Here is a small traditional Hello World program for the Atari Lynx.
43 tgi_install(tgi_static_stddrv);
49 tgi_setcolor(COLOR_GREEN);
50 tgi_outtextxy(0, 0, "Hello World");
57 The lynx.h contains all kind of system dependent things.
59 The tgi.h contains the graphics driver functions.
61 The 6502.h is needed for executing the CLI() command.
63 As the Atari Lynx does not have ASCII characters available you need to use
64 the Tiny Graphics Interface library for producing letters on the screen.
66 The cc65 compiler suite has a graphics library called "Tiny Graphics
67 Interface". This interface has some relocatable code. In order to use this
68 in your own program you need to load it at run time.
70 Unfortunately the Lynx does not have a disk drive from where to load it.
71 Therefore you must already load it at compile time. The easiest way is to
72 automatically link it in statically from the Lynx C library.
75 cl65 -t lynx -o game.lnx main.c
78 This will create a bootable cart image called game.lnx
81 <sect>Binary format<p>
83 The standard binary output format generated by the linker for the Lynx target
84 is a cart image. By specifying the config file lynx-bll.cfg the linker will
85 generate BLL download compatible binary files.
87 It is of course possible to change this behaviour by using a modified startup
88 file and linker config.
90 The bootloader used in the cc65 lynx library uses a very minimal bootloader
91 that does not check the cart or show a title screen.
93 The advantage of this bootloader is that it allows creation of cart images to
98 Block size Rom size Description
99 512 bytes 128k Standard old games like Warbirds
100 1024 bytes 256k Most common format for homebrew. Also newer games like Lemmings
101 2048 bytes 512k Largest games like EOTB
104 <sect>Memory layout<p>
106 cc65 generated programs with the default setup run with the I/O area and the
107 kernal enabled, which gives a usable memory range of $200 - $C037.
111 0000 - 00FF Zero page
112 0100 - 01FF Machine stack
114 A058 - C037 Collision buffer
115 C038 - E017 Screen buffer 1
116 E018 - FFF7 Screen buffer 0
117 FFF8 - FFFF Hardware vectors
122 No conio support is currently available for the Lynx.
125 The Lynx "flabode" keys, Opt 1, Pause and Opt 2 are implemented using the
126 conio interface. The only characters the keyboard is able to produce are
127 'R' for Restart (Opt 1 + Pause), 'F' for flip (Opt 2 + Pause),
128 'P' for pause, '1' for Opt 1, '2' for Opt 2, '3' for Opt 1 + Opt 2 and
129 '?' for all keys down at the same time.
132 The C runtime stack is located at $C037 (or $A057 if collision
133 detection is enabled) and growing downwards.
136 The C heap is located at the end of the program and grows towards the C
140 The collision detection screen is at $A058 if it is enabled. The
141 double buffered screens are at $C038 and $E018.
147 <sect>Platform specific header files<p>
149 Programs containing Lynx specific code may use the <tt/lynx.h/ header file.
152 <sect1>Lynx specific functions<p>
155 <item>lynx_eeprom_erase
156 <item>lynx_eeprom_read
157 <item>lynx_eeprom_write
166 <sect1>Hardware access<p>
168 The following pseudo variables declared in the <tt/lynx.h/ header file do
169 allow access to hardware located in the address space. Some variables are
170 structures, accessing the struct fields will access the chip registers.
174 <tag><tt/MIKEY/</tag>
175 The <tt/MIKEY/ structure allows access to MIKEY chip. See the <tt/_mikey.h/
176 header file located in the include directory for the declaration of the
180 The <tt/SUZY/ structure allows access to SUZY chip. See the <tt/_suzy.h/
181 header file located in the include directory for the declaration of the
188 <sect>Loadable drivers<p>
190 <sect1>Graphics drivers<p>
192 A TGI driver for the standard graphics mode (160×102 in 16 colors) is
193 available, but must be statically linked, because no file I/O is available.
195 The TGI driver is implemented as an interrupt driven dual buffering device.
196 To use it as a single-buffer device set draw page and view page to the same
199 The TGI driver has a few Lynx-specific extensions.
201 Calling tgi_sprite(spr) or tgi_ioctl(0, spr) will display a standard Lynx
204 Calling tgi_flip() or tgi_ioctl(1, 0) will do a flip screen.
206 Calling tgi_setbgcolor(bgcolor) or tgi_ioctl(2, bgindex) will set the text
207 background color to the index defined by bgindex. If bgindex is 0 then the
208 background color is transparent.
210 To set the framerate of the display hardware call tgi_setframerate(rate) or
211 tgi_ioctl(3, rate). The supported framerates are 50, 60 and 75 frames per
212 second. Actually there is no real reason to use anything else than 75 frames
215 To check if the drawing engine is busy with the previous swap you can
216 call tgi_busy or tgi_ioctl(4, 0). It returns 0 if idle and 1 if busy
218 To update displays you can call tgi_updatedisplay() or tgi_ioctl(4, 1) it
219 will wait for the next VBL interrupt and set the draw buffer to the
220 view buffer. The draw buffer is also changed to (drawbuffer xor 1).
222 You can also enable or disable collision detection by a call to
223 tgi_setcollisiondetection(active) or tgi_ioctl(5, active). The collision
224 result is located before the sprite structure by default in this driver.
226 In order to reserve memory for the collision detection buffer you need to
227 specify lynx-coll.cfg as the configuration file to the linker.
229 <sect1>Extended memory drivers<p>
231 No extended memory drivers are currently available for the Lynx.
234 <sect1>Joystick drivers<p>
236 A joystick driver for the standard buttons is available, but must be
237 statically linked, because no file I/O is available.
239 <sect1>Mouse drivers<p>
241 No mouse drivers are currently available for the Lynx.
244 <sect1>RS232 device drivers<p>
248 The ComLynx port has Tx and Rx wired together. Every byte is sent
249 to all connected Lynxes. Only one Lynx can send at a time. There is no
250 protocol created for communication. You are on your own.
252 If the Lynx returns framing error then it is likely that another Lynx is
253 sending data at the same time.
255 The Lynx can also send a break and receive a break. The Lynx break is
256 recognized if the bit is down for 24 bit cycles or more.
258 To send a break you just set the break bit. The length of the break depends
259 on how long this bit is down.
261 The driver supports the baudrates:
279 The parity bit supports MARK and SPACE. It also supports EVEN and ODD parity
280 but the parity bit is included in the calculation. Most of us don't want it
281 this way. But there is nothing we can do about it.
283 The Lynx hardware will always check parity on incoming traffic. Currently
284 the driver cannot receive data from standard PC's due to this parity bug.
285 For working with Lynx to Lynx communication use EVEN parity.
287 To send data to standard PC's use MARK or SPACE as parity setting.
289 There is always only one stop bit. And the data length is always 8 bits.
291 We have no handshaking available. Even software handshake is impossible
292 as ComLynx has only one wire for the data.
294 Both transmit and receive are interrupt driven.
305 At this point in time there is no support for the cart filesystem yet. I have
306 a <tt/lynx-cart-demo/ example project that uses an interrupt driven display,
307 has support for the cart filesystem and an abcmusic sound module.
309 At some point in time we may find a way to rewrite these to fit the way the
310 cc65 drivers require. But for the time being you can create less portable
311 applications using these Lynx specific modules in <tt/lynx-cart-demo/.
314 <sect>Bugs/Feedback<p>
316 If you have problems using the library, if you find any bugs, or if you're
317 doing something interesting with it, I would be glad to hear from you. Feel
318 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
319 name="uz@cc65.org">).
325 This software is provided 'as-is', without any expressed or implied
326 warranty. In no event will the authors be held liable for any damages
327 arising from the use of this software.
329 Permission is granted to anyone to use this software for any purpose,
330 including commercial applications, and to alter it and redistribute it
331 freely, subject to the following restrictions:
334 <item> The origin of this software must not be misrepresented; you must not
335 claim that you wrote the original software. If you use this software
336 in a product, an acknowledgment in the product documentation would be
337 appreciated but is not required.
338 <item> Altered source versions must be plainly marked as such, and must not
339 be misrepresented as being the original software.
340 <item> This notice may not be removed or altered from any source