INTRODUCTION
------------

Stella is the best emulator of Atari 2600 game
console, running on many different systems, such as
Linux, Solaris, Windows, MacOS/X WinCE, OS/2, GP2X.

It has been initially written by Bradford Mott
(see http://stella.sourceforge.net/)

GP2X2600 is a port on GP2X of my previous PSP 
port version.

CONTROL
------------

GP2X        Atari 2600
  
  A          R Diff A
  Y          Reset    
  X          Fire
  B          Select
  Up         Up
  Down       Down
  Left       Left
  Right      Right

LTrigger   Toogle with L keyboard mapping
RTrigger   Toggle with R keyboard mapping

LTrigger mapping :

  GP2X        Atari 2600
    
  A          Hotkey FPS
  Y          Hotkey Load state
  X          Hotkey Save state
  B          Hotkey render
  Up         Up
  Down       Down
  Left       Left
  Right      Right

RTrigger mapping :

  GP2X        Atari 2600 
    
  A          R Diff B
  Y          Reset 
  X          Hotkey auto-fire
  B          Select 
  Up         Up
  Down       Down
  Left       Left
  Right      Right


Press Menu      to enter in emulator main menu.
Press Select    open/close the virtual keyboard

Y          Go Up directory
X          Valid
B          Valid
A          Go Back to the emulator window

The On-Screen Keyboard of "Danzel" and "Jeff Chen"

Use digital pad to choose one of the 9 squares, and
use X, Y, A, B to choose one of the 4 letters of the
highlighted square.

Use LTrigger and RTrigger to see other 9 squares
figures.

LOADING ROM FILES (.A26 or .BIN)
------------

If you want to load rom images in the virtual drive
of your emulator, you have to put your rom file (with
.zip, .bin or .a26 file extension) on your SD memory
card in the 'roms' directory. 

Then, while inside Atari 2600 emulator, just press
SELECT to enter in the emulator main menu, choose
"Load ROM" and then using the file selector choose one
game file to load in your emulator. Back to the
emulator window, your game should run automatically.

LOADING KEY MAPPING FILES
------------

For given games, the default keyboard mapping between
GP2X Keys and Atari 2600 keys, is not suitable, and
the game can't be played on GP2X2600.

To overcome the issue, you can write your own mapping
file. Using notepad for example you can edit a file
with the .kbd extension and put it in the kbd 
directory.

For the exact syntax of those mapping files, have a
look on sample files already presents in the kbd
directory (default.kbd etc ...).

After writting such keyboard mapping file, you can
load them using the main menu inside the emulator.

If the keyboard filename is the same as the rom file
(.a26) then when you load this rom file, the
corresponding keyboard file is 
automatically loaded !

You can now use the Keyboard menu and edit, load and
save your keyboard mapping files inside the emulator.
The Save option save the .kbd file in the kbd
directory using the "Game Name" as filename. The game
name is displayed on the right corner in the emulator
menu.

CHEAT CODE (.CHT)
----------

  You can use cheat codes with this emulator.  You
can add your own cheat codes in the cheat.txt file
and then import them in the cheat menu.  

  All cheat codes you have specified for a game can
be save in a CHT file in 'cht' folder.  Those cheat
codes would then be automatically loaded when you
start the game.

The CHT file format is the following :
#
# Enable, Address, Value, Comment
#
1,36f,3,Cheat comment

  Using the Cheat menu you can search for modified
bytes in RAM between current time and the last time
you saved the RAM. It might be very usefull to find
"poke" address by yourself, monitoring for example
life numbers.

To find a new "poke address" you can proceed as
follow :

Let's say you're playing Moon patrol and you want to
find the memory address where "number lives" is
stored.

. Start a new game in Moon patrol
. Enter in the cheat menu. 
. Choose Save Ram to save initial state of the memory. 
. Specify the number of lives you want to find in
  "Scan Old Value" field.
  (for Glouton the initial lives number is 3)
. Go back to the game and loose a life.
. Enter in the cheat menu. 
. Specify the number of lives you want to find in
  "Scan New Value" field.
  (for Moon patrol the lives number is now 2)
. In Add Cheat you have now one matching Address
. Specify the Poke value you want (for example 3) 
  and add a new cheat with this address / value.

The cheat is now activated in the cheat list and you
can save it using the "Save cheat" menu.

Let's enjoy Moon patrol with infinite life !!

COMMENTS
------------

You can write your own comments for games using the
"Comment" menu.  The first line of your comments
would then be displayed in the file requester menu
while selecting the given file name (roms, keyboard,
settings).

SETTINGS
------------

You can modify several settings value in the settings
menu of this emulator.  The following parameters are
available :

Sound enable : 
  enable or disable the sound

Speed limiter :
  limit the speed to a given fps value

Skip frame : 
  to skip frame and increase emulator speed

Display fps : 
  display real time fps value 

Render mode : 
  many render modes are available with different
  geometry that should covered all games
  requirements

Delta Y : 
  move the center of the screen vertically

Vsync : 
  wait for vertical signal between each frame displayed

Flicker mode : 
  set flicker mode (none, simple, phosphor or average)
  
Clock frequency : 
  GP2X clock frequency, by default the value is set
  to 400Mhz, and should be enough for most of all
  games.

JOYSTICK SETTINGS
------------

You can modify several joystick settings value in the
settings menu of this emulator.  The following
parameters are available :

Swap Analog/Cursor : 
  swap key mapping between GP2X analog pad and GP2X
  digital pad

Active Joystick : 
  Joystick player, it could be 1 or 2

Paddle enable :
  enable or disable paddle

Paddle speed :
  specify paddle speed factor (from 1 to 3)

Auto fire period : 
  auto fire period

Auto fire mode : 
  auto fire mode active or not


FLICKERING 
------------

On several games such as Asteroids or Missile
Command, the screen flicks, or the color are dark.
You can then change the Flicker mode parameters in
the Settings menu. For example, Asteroids is very
nice using the "Simple" anti-flicker mode.

AUTO-FIRE
------------

It may happens that autofire can not be stopped. 
You have then to go to the settings menu and 
set auto fire option to off ...


  Enjoy,

            Zx

