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stella(6) Games Manual stella(6)

stella - Atari 2600 emulator

stella [options] <ROM file>

stella is a comprehensive emulator of the old Atari 2600 video-game console. It support most Atari 2600 games and many peripherals.

stella accepts the following options:

Use OpenGL, OpenGLES or SDL software rendering mode; the default is the best available mode detected.
Synchronize screen updates to the vertical blank period. This can result in smoother updates, and eliminate tearing.
Play the game in fullscreen mode (1) or in a window (0).
Centers game window (if possible).
Sets the palette to either normal Stella, the one used in the z26 emulator, or a user-defined palette.
Controls the emulation speed (as a percentage, between 10 and 1000, from one-tenth the native speed to ten times the native speed).
Enable or disable display of message in the UI. Note that messages indicating serious errors override this setting, and are always shown.
Enable or disable sound generation.
Specify the sound fragment size to use. Under Debian the recommended value is 512.
Set sound sample output frequency (0 - 48000). Default is 31400. Do not change unless you experience sound issues.
Set the volume (0 - 100).
Use the specified zoom level (integer) while in TIA/emulation mode.
Use interpolation for the TIA image (results in blending/smoothing of the image).
Specify the amount (as a percentage) to scale the TIA image width in NTSC and PAL mode. Since many video modes do not use square pixels, you can reduce width until the pixels appear square. Allowable values are 80-120; the author finds 85-90 gives the mos authentic look for NTSC, and 105-110 for PAL.
Stretch TIA image completely while in fullscreen mode (vs. an integral stretch which won't necessarily completely fill the screen).
Assigns the colours (r)ed, (o)range, (y)ellow, (g)reen, (b)lue and (p)urple to each graphical register P0/M0/P1/M1/PF/BL, respectively. Currently, these can be changed around to apply different colours to the respective register.
Blargg TV effects, 0 is disabled, next numbers in sequence represent presets for "Composite", "S-Video", "RGB", "Bad Adjust" and "Custom" modes.
Determines how phosphor mode is enabled. If always, then the ROM properties entry is ignored, and phosphor mode is always turned on. Otherwise, the ROM properties determine whether phosphor mode is used for each ROM.
TV effects scanline intensity, where 0 means completely off.
Blargg TV effects scanline interpolation, resulting in blending/smoothing of the scanlines.
Blargg TV effects 'contrast' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'brightness' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'hue' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'saturation' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'gamma' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'sharpness' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'resolution' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'artifacts' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'fringing' (only available in custom mode, range -1.0 to 1.0).
Blargg TV effects 'bleed' (only available in custom mode, range -1.0 to 1.0).
Use the specified cheatcode (see the Cheat section in the provided documentation for a description of cheatcodes).
Indicates level of logging to perform while the application is running. Zero completely disables logging (except for serious errors), while the remaining numbers show increasingly more detail.
Indicates that logged output should be printed to the console/commandline as it's being collected. An internal log will still be kept, and the amount of logging is still controlled by loglevel.
Sets the joystick deadzone area for analog joysticks. Accepts a number from 0 - 29, and uses the formula 3200 + number * 1000. So the possible deadzone values range from 3200 to 32200.
Allow all 4 directions on a joystick to be pressed simultaneously. Bumper Bash ignores this setting, and always allows all 4 directions.
Use mouse as a controller as specified by ROM properties in specific case. always and never are self-explanatory, analog means only for analog-type devices (paddles, trackball, etc.).
Keeps the mouse in the game window in emulation mode.
Set mouse cursor state in UI/emulation modes.
Sensitivity for emulation of paddles when using a digital device (joystick digital axis or button, keyboard key, etc.). number may range from 1 to 20, with larger numbers causing faster movement.
Sensitivity for emulation of paddles when using a mouse. number may range from 1 to 20, with larger numbers causing faster movement.
Sensitivity for emulation of trackball controllers when using a mouse. number may range from 1 to 20, with larger numbers causing faster movement.
Determines how to enumerate the Stelladaptor/2600-daptor devices in the order they are found: 'lr' means first is left port, second is right port, 'rl' means the opposite.
Use control-x key combos. This is normally enabled, since the Quit command is tied to 'Control-q'. However, there are times when a 2-player game is using either the 'f' or 'r' keys for movement, and pressing Control (for Fire) will perform an unwanted action associated with Control-r or Control-f.
Automatically switch to the next available save state slot after saving a ROM state file.
Disable Supercharger BIOS progress loading bars.
The directory to save snapshot files to.
The directory to load snapshot files from.
When saving snapshots, use either the internal database name or the actual ROM filename.
Generate single snapshot instead of many, overwriting any previous snapshots.
Ignore any scaling applied to the TIA image, and save snapshot in unscaled (1x) mode.
Set the interval in seconds between taking snapshots in continuous snapshot mode (currently, 1 - 10).
Display detailed information about the given ROM, and then exit Stella.
Prints relevant contents of the Stella ROM database, one ROM per line, and then exit Stella. This can be used for external frontends.
Always exit to ROM launcher when exiting a ROM (normally, an exit to launcher only happens when started with the launcher).
Set the size of the ROM launcher.
Set the size of the font in the ROM launcher.
Specifies whether to show ROMs only (the default) or all files in the ROM launcher.
Hide ROM info viewer in ROM launcher mode (0), or use the given zoom level (1 or 2).
Use the specified palette for UI elements.
Set the amount of time to wait between treating successive keypresses as a single word in list widgets (value can range from 300-1000).
Set the number of lines a mousewheel will scroll in the UI.
Set the directory where the ROM launcher will start.
Set the directory in which to save state files.
Set the full pathname of the cheatfile database.
Set the full pathname of the user-defined palette file.
Set the full pathname of the ROM properties file.
Set the directory in which to save EEPROM files.
Set the directory in which to access Distella config files.
Set the name of the serial port where an AtariVox is connected.
Useful for developers, this sets the maximum size of window that can be created, allowing to simulate testing on 'smaller' systems.
Print a help message describing these options, and then exit Stella.

The following are useful to developers. Only use them if you know what you're doing! Note that in all cases, the values supplied to the arguments are not case sensitive.

Try to differentiate between code vs. data sections in the disassembler. See the Debugger section in the provided documentation for more information.
Sets the base to use for displaying GFX sections in the disassembler.
Shows/hides opcode addresses in the disassembler.
Relocate calls out of address range in the disassembler.
Set the size of the debugger window.
Set the font size in the debugger window.
How to use bold fonts in the debugger window. 0 means all normal font, 1 is bold labels only, 2 is bold non-labels only, 3 is all bold font.
Debugger considers/ignores 'ghost' reads for trap addresses.
Lower/uppercase hexadecimal display.
Set a breakpoint at a specified address.
Immediately jump to debugger mode when starting Stella.
Start the emulator with the specified left joystick direction and button held down (UF for up and fire). After entering the emulation, you will have to press and release the direction again to release the event.
Start the emulator with the specified right joystick direction and button held down (UF for up and fire). After entering the emulation, you will have to press and release the direction again to release the event.
Start the emulator with the Game Select switch held down. After entering the emulation, you will have to press and release 'Select' to release the event.
Start the emulator with the Game Reset switch held down. After entering the emulation, you will have to press and release 'Reset' to release the event.
Set "Cartridge.Type" property. See the Game Properties section in the provided documentation for valid types.
Set "Cartridge.Sound" property.
Set "Console.LeftDifficulty" property.
Set "Console.RightDifficulty" property.
Set "Console.TelevitionType" property.
Set "Console.SwapPorts" property.
Set "Controller.Left" property. See the Game Properties section in the provided documentation for valid types.
Set "Controller.Right" property. See the Game Properties section in the provided documentation for valid types.
Sets both "Controller.Left" and "Controller.Right" properties. See the Game Properties section in the provided documentation for valid types.
Set "Controller.SwapPaddles" property. See the Game Properties section in the provided documentation for valid types.
Set "Controller.MouseAxis" property. See the Game Properties section in the provided documentation for valid types.
Set "Display.Format" property. See the Game Properties section in the provided documentation for valid formats.
Set "Display.YStart" property (0 - 64).
Set "Display.Height" property (210 - 256).
Set "Display.Phosphor" property.
Set "Display.PPBlend" property, used for phosphor effect (0-100). Default is 77.

The following are available in two sets, one for players (prefixed by plr.) and one for developers (prefixed by dev.). Only use them if you know what you're doing! Note that in all cases, the values supplied to the arguments are not case sensitive.

Select developer (1) or player (0) set.
-<plr|dev>.stats <1|0>
Overlay console info on the TIA image during emulation.
-<plr|dev>.console <2600|7800>
Select console for B/W and Pause key handling and RAM initialization.
-<plr|dev>.bankrandom <1|0>
On reset, randomize the startup bank (only for selected bankswitch types).
-<plr|dev>.ramrandom <1|0>
On reset, either randomize all RAM content, or zero it out instead.
-<plr|dev>.cpurandom [SAXYP]
On reset, randomize the content of the specified CPU registers.
-<plr|dev>.tiadriven <1|0>
Set unused TIA pins to be randomly driven high or low on a read/peek.
-<plr|dev>.rwportbreak <1|0>
Since the 2600 has no dedicated R/W line, different addresses are used for RAM read or write access. If the code reads from such a write address, this causes an unwanted, semi-random write to that address. When this option is enabled, such reads interrupt emulation and the debugger is entered.
-<plr|dev>.thumb.trapfatal <true|false>
The default of true allows the Thumb ARM emulation to throw an exception and enter the debugger on fatal errors. When disabled, such fatal errors are simply logged, and emulation continues. Do not use this unless you know exactly what you're doing, as it changes the behaviour as compared to real hardware.
-<plr|dev>.eepromaccess <1|0>
When enabled, each read or write access to the AtariVox/SaveKey EEPROM is signalled by a message.
-<plr|dev>.tv.jitter <1|0>
Enable TV jitter/roll effect, when there are too many or too few scanlines per frame.
-<plr|dev>.tv.jitter_recovery <1-20>
When TV jitter/roll effect is enabled, determines how long to delay recovery time (recovery spread over multiple frames).
-<plr|dev>.colorloss <1|0>
Enable/disable the PAL color-loss effect.
-<plr|dev>.debugcolors <1|0>
Enable/disable the fixed debug colors.
-<plr|dev>.timemachine <1|0>
Enables the Time Machine.
-<plr|dev>.tm.size <20-1000>
Defines the Time Machine buffer size.
-<plr|dev>.tm.uncompressed <0-1000>
Defines the uncompressed Time Machine buffer size. Must be less than Time Machine the buffer size.
-<plr|dev>.tm.interval <1f|3f|10f|30f|1s|3s|10s>
Defines the interval between two save states.
-<plr|dev>.tm.horizon <3s|10s|30s|1m|3m|10m|30m|60m>
Defines the horizon of the Time Machine.

The Atari 2600 console controls and controllers are mapped to the computer's keyboard as shown in the following sections. However, most of these events can be remapped to other keys on your keyboard or buttons on your joystick.

Control + q
Exit emulator
Exit game mode/enter launcher mode
Enter/exit options mode
Enter/exit command mode
Enter/exit debugger
Select Game
Reset Game
Color TV
Black/White TV
Left Player Difficulty A
Left Player Difficulty B
Right Player Difficulty A
Right Player Difficulty B
Save state to current slot
Change current state slot
Load state from current slot
Save PNG snapshot
Pause/resume emulation

Left joystick:

Up arrow
Joystick up
Down arrow
Joystick down
Left arrow
Joystick left
Right arrow
Joystick right
Fire button
4
Trigger button
5
Booster button

Right joystick:

Joystick up
Joystick down
Joystick left
Joystick right
Fire button
6
Trigger button
7
Booster button

By default the left paddles are mapped to the left joystick as follows:

Paddle 0 decrease
Paddle 0 increase
Paddle 0 fire
Paddle 1 decrease
Paddle 1 increase
Paddle 1 fire

The same mappings on the right joystick correspond to the right paddles (paddles 2 and 3 respectively).

Each driving controller is mapped to the corresponding joystick, using the left, right and fire controls.

Each pad is mapped to the correspondig joystick as follows:

Up
Down
Left
Right
Button 'B'
Button 'C'

Left keypad (press the key on the left to emulate the key on the right):

1
1
2
2
3
3
4
5
6
7
8
9
.
0
#

Right keypad:

8
1
9
2
0 (the digit)
3
4
5
6
7
8
;
9
,
.
.
0
/
#

0-9
0-9
A-Z
Comma
Period
Func
Shift
; or Return/Enter
Enter
/ or Space
Space
Func-Space

~/.config/stella/stellarc
Default options (command line options override these). Lines starting with ';' are considered comments and are ignored. Any other line must be of the form <command> = <value>, where command is the same as that specified on the command line, without the '-' character, and value is the value given to the setting.
~/.config/stella/atarivox_eeprom.dat
Default storage for the emulated EEPROM portion of an attached AtariVox device.
~/.config/stella/savekey_eeprom.dat
Default storage for the emulated EEPROM portion of an attached SaveKey device.
~/.config/stella/stella.cht
Default location of the cheat database file.

/usr/share/doc/stella/index.html, /usr/share/doc/stella/debugger.html.

stella was written by Bradford W. Mott, Stephen Anthony and the Stella Team.

This manual page was adapted from the provided documentation by Stephen Kitt <skitt@debian.org>, for the Debian GNU/Linux system (but may be used by others). It was last modified for stella version 6.0.

January 12, 2019 stella