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