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>Binary format<p>
35 The standard binary output format generated by the linker for the Lynx target
36 is a machine language program with an executable header. It is of course
37 possible to change this behaviour by using a modified startup file and linker
40 You can also produce real carts with directory structures and encrypted
41 headers by modifying the startup and linker config files. There is a simple
42 example archive called <tt/lynx-cart-demo/ in the <htmlurl
43 url="ftp://ftp.musoftware.de/pub/uz/cc65/contrib/" name="contrib directory">
44 that shows how to create a complete bootable Lynx cart.
46 <sect>Memory layout<p>
48 cc65 generated programs with the default setup run with the I/O area and the
49 kernal enabled, which gives a usable memory range of $400 - $C037.
55 No conio support is currently available for the Lynx.
58 The Lynx "flabode" keys, Opt 1, Pause and Opt 2 are implemented using the
59 conio interface. The only characters the keyboard is able to produce are
60 'R' for Restart (Opt 1 + Pause), 'F' for flip (Opt 2 + Pause),
61 'P' for pause, '1' for Opt 1, '2' for Opt 2, '3' for Opt 1 + Opt 2 and
62 '?' for all keys down at the same time.
65 The C runtime stack is located at $C037 (or $A057 if collision
66 detection is enabled) and growing downwards.
69 The C heap is located at the end of the program and grows towards the C
73 The collision detection screen is at $A058 if it is enabled. The
74 double buffered screens are at $C038 and $E018.
80 <sect>Platform specific header files<p>
82 Programs containing Lynx specific code may use the <tt/lynx.h/ header file.
85 <sect1>Lynx specific functions<p>
88 <item>lynx_eeprom_erase
89 <item>lynx_eeprom_read
90 <item>lynx_eeprom_write
95 <sect1>Hardware access<p>
97 The following pseudo variables declared in the <tt/lynx.h/ header file do
98 allow access to hardware located in the address space. Some variables are
99 structures, accessing the struct fields will access the chip registers.
103 <tag><tt/MIKEY/</tag>
104 The <tt/MIKEY/ structure allows access to MIKEY chip. See the <tt/_mikey.h/
105 header file located in the include directory for the declaration of the
109 The <tt/SUZY/ structure allows access to SUZY chip. See the <tt/_suzy.h/
110 header file located in the include directory for the declaration of the
117 <sect>Loadable drivers<p>
119 <sect1>Graphics drivers<p>
121 A TGI driver for the standard graphics mode (160×102 in 16 colors) is
122 available, but must be statically linked, because no file I/O is available.
123 See the documentation for the <htmlurl url="co65.html" name="co65 utility">
124 for information on how to do that.
126 The TGI driver is implemented as an interrupt driven dual buffering device.
127 To use it as a single-buffer device set draw page and view page to the same
130 The TGI driver has a few Lynx-specific extensions.
132 Calling tgi_sprite(spr) or tgi_ioctl(0, spr) will display a standard Lynx
135 Calling tgi_flip() or tgi_ioctl(1, 0) will do a flip screen.
137 Calling tgi_setbgcolor(bgcolor) or tgi_ioctl(2, bgindex) will set the text
138 background color to the index defined by bgindex. If bgindex is 0 then the
139 background color is transparent.
141 To set the framerate of the display hardware call tgi_setframerate(rate) or
142 tgi_ioctl(3, rate). The supported framerates are 50, 60 and 75 frames per
143 second. Actually there is no real reason to use anything else than 75 frames
146 To check if the drawing engine is busy with the previous swap you can
147 call tgi_busy or tgi_ioctl(4, 0). It returns 0 if idle and 1 if busy
149 To update displays you can call tgi_updatedisplay() or tgi_ioctl(4, 1) it
150 will wait for the next VBL interrupt and set the draw buffer to the
151 view buffer. The draw buffer is also changed to (drawbuffer xor 1).
153 You can also enable or disable collision detection by a call to
154 tgi_setcollisiondetection(active) or tgi_ioctl(5, active). The collision
155 result is located before the sprite structure by default in this driver.
157 <sect1>Extended memory drivers<p>
159 No extended memory drivers are currently available for the Lynx.
162 <sect1>Joystick drivers<p>
164 A joystick driver for the standard buttons is available, but must be
165 statically linked, because no file I/O is available. See the documentation for
166 the <htmlurl url="co65.html" name="co65 utility"> for information on how to do
169 The joystick will check to see if the screen is flipped or not in the install
170 routine and adapt itself to the correct state.
172 <sect1>Mouse drivers<p>
174 No mouse drivers are currently available for the Lynx.
177 <sect1>RS232 device drivers<p>
181 The ComLynx port has Tx and Rx wired together. Every byte is sent
182 to all connected Lynxes. Only one Lynx can send at a time. There is no
183 protocol created for communication. You are on your own.
185 If the Lynx returns framing error then it is likely that another Lynx is
186 sending data at the same time.
188 The Lynx can also send a break and receive a break. The Lynx break is
189 recognized if the bit is down for 24 bit cycles or more.
191 To send a break you just set the break bit. The length of the break depends
192 on how long this bit is down.
194 The driver supports the baudrates:
212 The parity bit supports MARK and SPACE. It also supports EVEN and ODD parity
213 but the parity bit is included in the calculation. Most of us don't want it
214 this way. But there is nothing we can do about it.
216 The Lynx hardware will always check parity on incoming traffic. Currently
217 the driver cannot receive data from standard PC's due to this parity bug.
218 For working with Lynx to Lynx communication use EVEN parity.
220 To send data to standard PC's use MARK or SPACE as parity setting.
222 There is always only one stop bit. And the data length is always 8 bits.
224 We have no handshaking available. Even software handshake is impossible
225 as ComLynx has only one wire for the data.
227 Both transmit and receive are interrupt driven. The driver reserves a fixed
228 area $200-$2ff for the transmit ring buffer and $300-$3ff for the receive
229 ring buffer. This area can not be used at startup for anything as the Lynx
230 ROM needs this area for decryption purposes.
241 At this point in time there is no support for the cart filesystem yet. I have
242 a <tt/lynx-cart-demo/ example project that uses an interrupt driven display,
243 has support for the cart filesystem and an abcmusic sound module.
245 At some point in time we may find a way to rewrite these to fit the way the
246 cc65 drivers require. But for the time being you can create less portable
247 applications using these Lynx specific modules in <tt/lynx-cart-demo/.
250 <sect>Bugs/Feedback<p>
252 If you have problems using the library, if you find any bugs, or if you're
253 doing something interesting with it, I would be glad to hear from you. Feel
254 free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
255 name="uz@cc65.org">).
261 This software is provided 'as-is', without any expressed or implied
262 warranty. In no event will the authors be held liable for any damages
263 arising from the use of this software.
265 Permission is granted to anyone to use this software for any purpose,
266 including commercial applications, and to alter it and redistribute it
267 freely, subject to the following restrictions:
270 <item> The origin of this software must not be misrepresented; you must not
271 claim that you wrote the original software. If you use this software
272 in a product, an acknowledgment in the product documentation would be
273 appreciated but is not required.
274 <item> Altered source versions must be plainly marked as such, and must not
275 be misrepresented as being the original software.
276 <item> This notice may not be removed or altered from any source