DOKK / manpages / debian 12 / stella / stella.6.en
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).
Center all windows (if possible).
Set the window position in windowed emulator mode.
Set the display for Stella's emulator.
Sets the palette to either normal Stella, the one used in the z26 emulator, or a user-defined palette.
Adjust phase shift of 'custom' NTSC palette.
Adjust phase shift of 'custom' PAL palette.
Adjust hue of current palette (range -1.0 to 1.0).
Adjust saturation of current palette (range -1.0 to 1.0).
Adjust contrast of current palette (range -1.0 to 1.0).
Adjust brightness of current palette (range -1.0 to 1.0).
Adjust gamma of current palette (range -1.0 to 1.0).
Controls the emulation speed (as a percentage, between 10 and 1000, from one-tenth the native speed to ten times the native speed).
Enable 'Turbo' mode for maximum emulation 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.
Set the volume (0 - 100).
Set the audio device (0 for the default device).
Set an audio preset. Numbers in sequence represent presets for 'custom', 'low quality, medium lag', 'high quality, medium lag', 'high quality, low lag' and 'ultra quality, minimal lag'.
Set the number of samples in a single fragment processed by the audio driver. number must be a power of two between 128 and 4096 inclusive. Under Debian the recommended value is 512.
Set sound sample output frequency.
Set resampling quality to low (1), high (2) or ultra (3).
Set number of additional half-frames to prebuffer.
Set maximum number of additional half-frames to buffer.
Enable or disable stereo mode for all ROMs.
Set the pitch of Pitfall II music.
Use the specified zoom level (integer) while in TIA/emulation mode.
Adjust the display height of the TIA image.
Use interpolation for the TIA image (results in blending/smoothing of the image).
Stretch TIA image completely while in fullscreen mode, vs. keeping the correct aspect ratio.
Add overscan to TIA image while in fullscreen mode
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.
Enable aspect ratio correct scaling.
Blargg TV effects, 0 is disabled, next numbers in sequence represent presets for "Composite", "S-Video", "RGB", "Bad Adjust" and "Custom" modes.
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).
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.
Enable phosphor blending level; 0 implies no mixing, and 100 is full mixing (not recommended). Note that this doesn't actually enable phosphor mode; that is done for each ROM in the ROM properties. Higher blend values will intensify the phosphor effect. Depending on your display and personal preferences, the optimal default for you may vary. Slow LCDs (especially for office use) may only need a low blend of around 30, while fast switching gamer LCDs may need about 70 to look similar to a CRT.
TV effects scanline intensity, where 0 means completely off.
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.
Sensitivity for emulation of paddles when using analog paddles. Valid range of values is from 1 to 30, with larger numbers causing faster movement
Strength of paddle input averaging.
Impact of fast paddle movement on input averaging.
Sensitivity for emulation of driving controllers when using a mouse. Valid range of values is from 1 to 20, with larger numbers causing faster movement.
Automatic trigger rate of the fire buttons in Hz (0 = disabled)
Allow all 4 directions on a joystick to be pressed simultaneously. Bumper Bash ignores this setting, and always allows all 4 directions.
Use modifier (Shift/Alt/Control)-x key combos. This is normally enabled, since the 'Quit' command is tied to 'Control-q'. However, there are times when you want to disable them. E.g. 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 default keys.
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.
Set the name of the serial port where an AtariVox is connected.
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.).
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.
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.
Set mouse cursor state in UI/emulation modes.
Keeps the mouse in the game window in emulation mode.
Automatically switch to the next available save state slot after saving a ROM state file.
Automatically save no, current or all states when exiting emulation. The latter also loads all states when entering emulation.
Disable Supercharger BIOS progress loading bars.
Enable multi-threaded video rendering (may not improve performance on all systems).
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 window position in windowed ROM launcher mode.
Set the display for the ROM 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 size of the font in the dialogs.
Set the position of dialogs within Stella windows (0 = center).
Enables the HiDPI mode which scales the UI by a factor of two.
Display a popup when emulation is exited.
Set the amount of time to wait between treating successive keypresses as a single word in list widgets (value can range from 300-1000). Use 0 to disable list-skipping completely.
Set the number of lines a mousewheel will scroll in the UI.
Set the mouse double click speed in the UI (100-900 ms).
Set the delay before controller input will start repeating in the UI (200-1000 ms).
Set the controller repeat rate in the UI (2-30 repeats/s).
Set the directory where the ROM launcher will start.
Make the start path follow ROM launcher navigation.
Useful for developers, this sets the maximum size of window that can be created, allowing to simulate testing on 'smaller' systems.
Override the base directory for all config files.
Override the base directory for all config files by attempting to use the application directory. For now this is only supported in Windows.
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 window position in windowed debugger mode.
Set the display for the debugger.
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.
Sets "Cartridge.StartBank" property.
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 Controller Properties section in the provided documentation for valid types.
Set "Controller.Left1" property for QuadTari. See the QuadTari Properties section in the provided documentation for valid types.
Set "Controller.Left2" property for QuadTari. See the QuadTari Properties section in the provided documentation for valid types.
Set "Controller.Right" property. See the Controller Properties section in the provided documentation for valid types.
Set "Controller.Right1" property for QuadTari. See the QuadTari Properties section in the provided documentation for valid types.
Set "Controller.Right2" property for QuadTari. See the QuadTari Properties section in the provided documentation for valid types.
Sets both "Controller.Left" and "Controller.Right" properties. See the Controller Properties section in the provided documentation for valid types.
Set "Controller.Left1", "Controller.Left2", "Controller.Right1" and "Controller.Right2" properties for QuadTari. See the QuadTari Properties section in the provided documentation for valid types.
Set "Controller.SwapPaddles" property. See the Controller Properties section in the provided documentation for valid types.
Set "Controller.PaddlesXCenter" property.
Set "Controller.PaddlesYCenter" property.
Set "Controller.MouseAxis" property. See the Controller Properties section in the provided documentation for valid types.
Set "Display.Format" property. See the Emulation Properties section in the provided documentation for valid formats.
Set "Display.VCenter" property (-5..5).
Set "Display.Phosphor" property.
Set "Display.PPBlend" property, used for phosphor effect (0-100). Default is whatever is specified for tv.phosblend.

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>.detectedinfo <1|0>
Display detected settings info when a ROM is loaded.
-<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.
Set unused TIA pins to be randomly driven high or low on a read/peek.
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.
Same as above. If the code writes to such a read address, nothing happens. But a developer should be made aware of it, because this indicates a problem with the code. When this option is enabled, such writes interrupt emulation and the debugger is entered.
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.
Set emulated TIA type.
Enable/disable inverted HMOVE clock phase for players (Kool Aid Man glitch).
Enable/disable inverted HMOVE clock phase for missiles (Cosmic Ark stars glitch).
Enable/disable inverted HMOVE clock phase for ball.
Enable/disable playfield bits delayed by one color clock (stray playfield pixels in Pesco).
Enable/disable playfield color delayed by one color clock (colored step borders in Quick Step!).
Enable/disable background color delayed by one color clock (stray pixels in Indy 500 menu hack).
Enable/disable player swap delayed by one color clock (He-Man title glitch).
Enable/disable ball swap delayed by one color clock.
-<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
Save all Time Machine states
Shift + F10
Change to previous state slot
Change to next state slot
Automatically change state slot
Load state from current slot
Load all states into Time Machine
Save PNG snapshot
Pause/resume emulation

Left joystick:

Up arrow
Joystick up
Down arrow
Joystick down
Left arrow
Joystick left
Right arrow
Joystick right
Left Control, Space
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 corresponding 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

Disable TV effects
Select 'RGB' preset
Select 'S-Video' preset
Select 'Composite' preset
Select 'Badly adjusted' preset
Select 'Custom' preset
Shift + Alt + 7
Select previous 'Custom' mode attribute (in 'Custom' preset mode)
Select next 'Custom' mode attribute (in 'Custom' preset mode)
Shift + Alt + 8
Decrease 'Custom' selected attribute value (in 'Custom' preset mode)
Increase 'Custom' selected attribute value (in 'Custom' preset mode)
Toggle 'phosphor' effect
Shift + Alt + 9
Decrease 'phosphor' blend in phosphor mode
Increase 'phosphor' blend in phosphor mode
Shift + Alt + 0
Decrease scanline intensity
Increase scanline intensity

Toggle frame stats (scanline count/FPS/BS type etc.)
Toggle TIA Player0 object
Toggle TIA Player1 object
Toggle TIA Missile0 object
Toggle TIA Missile1 object
Toggle TIA Ball object
Toggle TIA Playfield object
Toggle all TIA objects
Shift + Alt + z
Toggle TIA Player0 collisions
Shift + Alt + x
Toggle TIA Player1 collisions
Shift + Alt + c
Toggle TIA Missile0 collisions
Shift + Alt + v
Toggle TIA Missile1 collisions
Shift + Alt + b
Toggle TIA Ball collisions
Shift + Alt + n
Toggle TIA Playfield collisions
Shift + Alt + Comma
Toggle all TIA collisions
Toggle TIA 'Fixed Debug Colors' mode
Control + L
Toggle PAL color-loss effect
Toggle TV 'Jitter' effect

Switch to next larger zoom level in windowed mode, toggle stretching in fullscreen mode
Switch to next smaller zoom level in windowed mode, toggle stretching in fullscreen mode
Toggle fullscreen/windowed mode
Shift + PageUp
Increase overscan in fullscreen mode
Shift + PageDown
Decrease overscan in fullscreen mode
Move display up (uses "Display.VCenter")
Move display down (uses "Display.VCenter")
Control + f
Switch display format in increasing order (NTSC/PAL/SECAM etc.)
Shift + Control + f
Switch display format in decreasing order (NTSC/PAL/SECAM etc.)
Control + p
Switch palette (Standard/Z26/User)
Control + i
Toggle display interpolation
Control + ]
Toggle sound on/off
Decrease volume
Increase volume
Control + 0
Switch mouse between controller emulation modes (see Game Properties - Controller)
Control + g
Toggle grab mouse
Control + 1
Swap Stelladaptor/2600-daptor port ordering
Control + r
Reload current ROM (singlecart ROM, TIA mode), load next game in ROM (multicart ROM, TIA mode), reload ROM listing (ROM launcher mode)
Emulate 'frying' effect (TIA mode), go to parent directory (UI mode)
Save continuous PNG snapshots (per interval defined in Snapshot Settings)
Shift + Alt + s
Save continuous PNG snapshots (every frame)
Toggle 'Time Machine' mode
Enter the Time Machine dialog
Exit the Time Machine dialog
Rewind by one state (enters the Time Machine dialog)
Shift + Alt + Left arrow
Rewind by 10 states (enters the Time Machine dialog)
Rewind all states (enters the Time Machine dialog)
Unwind by one state (enters the Time Machine dialog)
Shift + Alt + Right arrow
Unwind by 10 states (enters the Time Machine dialog)
Unwind all states (enters the Time Machine dialog)

Move cursor to beginning of line
Move cursor to end of line
Remove character to right of cursor
Remove character to left of cursor
Control + a
Same function as 'Home'
Control + e
Same function as 'End'
Control + d
Same function as 'Delete'
Control + k
Remove all characters from cursor to end of line
Control + u
Remove all characters from cursor to beginning of line
Control + w
Remove entire word to left of cursor
Control + Left
Move cursor to beginning of word to the left
Control + Right
Move cursor to beginning of word to the right
Control + c
Copy entire line to clipboard (not complete)
Control + v
Paste clipboard contents (not complete)

~/.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/nvram/atarivox_eeprom.dat
Default storage for the emulated EEPROM portion of an attached AtariVox device.
~/.config/stella/nvram/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 6.1.

May 21, 2020 stella