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Docs for the serial functions by Karri Kaksonen.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4980 b7a2c559-68d2-44c3-8de9-860c34a00d81
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2011-04-06 19:50:26 +00:00
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doc/lynx.sgml
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@@ -5,7 +5,7 @@
<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>2004-10-14
<date>2011-04-01
<abstract>
An overview over the Atari Lynx runtime system as it is implemented for the
@@ -30,24 +30,111 @@ more than one platform. Please see the function reference for more
information.
<sect>Building you 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>
extern char lynxtgi[];
void main(void) {
tgi_install(&amp;lynxtgi);
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 link it in statically.
This relocatable driver is found in $(CC65_HOME)/tgi/lynx-160-102-16.tgi. Copy it from here.
The name comes from 160 by 102 pixels (The Lynx LCD size), 16 colors.
In order to link in this statically we have to make it back to a source file so that we can compile it. The next command will turn the compiled driver object file into an assembler source and compile it with the ca65 assembler.
<tscreen><verb>
co65 --code-label _lynxtgi lynx-160-102-16.tgi
ca65 -t lynx lynx-160-102-16.s
</verb></tscreen>
This will create a linkable object file called lynx-160-102-16.o
Then we need to compile our main file to a linkable object file.
<tscreen><verb>
cc65 -t lynx main.c
ca65 -t lynx main.s
</verb></tscreen>
Finally we have to link them together to produce an executable cart.
<tscreen><verb>
cl65 -t lynx -o game.lnx main.o lynx-160-102-16.o lynx.lib
</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. It is of course possible to change this behaviour by using a
modified startup file and linker config.
is a cart image. By specifying the config file lynx-bll.cfg the linker will
generate BLL download compatible binary files.
You can also produce real carts with directory structures and encrypted
headers by modifying the startup and linker config files. There is a simple
example archive called <tt/lynx-cart-demo/ in the <htmlurl
url="ftp://ftp.musoftware.de/pub/uz/cc65/contrib/" name="contrib directory">
that shows how to create a complete bootable Lynx cart.
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 &dollar;400 - &dollar;C037.
kernal enabled, which gives a usable memory range of &dollar;200 - &dollar;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/
@@ -153,6 +240,9 @@ 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.
<sect1>Extended memory drivers<p>
No extended memory drivers are currently available for the Lynx.
@@ -165,9 +255,6 @@ statically linked, because no file I/O is available. See the documentation for
the <htmlurl url="co65.html" name="co65 utility"> for information on how to do
that.
The joystick will check to see if the screen is flipped or not in the install
routine and adapt itself to the correct state.
<sect1>Mouse drivers<p>
No mouse drivers are currently available for the Lynx.
@@ -223,10 +310,7 @@ No mouse drivers are currently available for the Lynx.
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. The driver reserves a fixed
area $200-$2ff for the transmit ring buffer and $300-$3ff for the receive
ring buffer. This area can not be used at startup for anything as the Lynx
ROM needs this area for decryption purposes.
Both transmit and receive are interrupt driven.
</descrip><p>
@@ -235,7 +319,7 @@ No mouse drivers are currently available for the Lynx.
<sect>Other hints<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,