The following are a list of common questions that seem to keep popping up on the support lists and on the AtariAge forums (in no particular order):

There are some graphical bugs in a game I'm playing, or the emulation seems to be inaccurate in some way.

The answer to this one should be obvious, but surprisingly enough, it isn't. If you think you've found a bug in the application, let us know about it. Perhaps it isn't a bug after all, but if it is, we can't fix it unless we know about it. Free and open source software is a two-way street, and users should report problems whenever they find them. In return, developers are usually happy to fix their programs, if possible. But keep in mind that reporting the bug doesn't guarantee an immediate fix; there may be other issues that need to be fixed first. But we can guarantee what will happen if you don't report a bug, and the developer never finds out about it - nothing.

In some games, the image seems to be off-center, usually pushed to the right.

Most (all?) of the time, this is caused by accurate emulation of the video processor in a real console. In other words, the same thing would happen on a real TV. Since Stella is all about emulating a real console as closely as possible, this is not a bug, and won't be 'fixed'. Technically, it is known as HMOVE blanking, the specifics of which you can find documented in the Stella Programmer's Guide.

Stella crashes immediately after starting, or seems completely broken.

My advice in this case (before reporting it as a bug) is to delete the settings file, and restart the application. The settings file is stored in different places depending on the operating system you're using:

Very Important:  Un-installing and re-installing the application will have absolutely no effect on your settings file. This is a commonly reported practice, but it is completely unnecessary. In all but the rarest cases, there will be nothing wrong with the application itself, so it doesn't need to be re-installed.

I can't find instructions on how to accomplish a task, or the manual is too long and I can't be bothered to read through it all.

Stella is a complex program which has many goals. It is meant to be an easy-to-use emulator for those wishing to just jump in and play a game, but it also comes with very complex developer options. As the saying goes: 'with great power comes great responsibility'. There are many options to explain, and as such, the manual is necessarily long.

That being said, recent versions of the manual are organized into 'Getting Started' and 'Advanced Configuration' sections, with many subsections below those. So don't be discouraged by the size of the manual. Most of the time, much of the manual can be ignored completely. And if all else fails, you can use the search function in your web browser :)

Where can I find some ROMs, and how do I start playing a game?

This is mentioned near the very beginning of the manual. The premiere website for all things Atari-related is AtariAge. As for how to start playing a game, I refer you to the 'Getting Started' section of the manual, as mentioned in a previous FAQ item.

When starting Stella and entering the ROM launcher, it sometimes takes up to 30 seconds to see the list of ROMs.

This could be caused by several issues; the most probable reason has been fixed in version 3.5. Otherwise, you could be attempting to access ROMs stored on a (slow) network drive. This one is outside the scope of Stella. Perhaps check your network settings, cables, etc to diagnose the problem.

After starting a ROM, there can sometimes be a delay of up to 5-10 seconds before the game starts playing. Or after exiting Stella, there is sometimes a similar delay.

This could be caused by several issues, but most of them are related to a 'timeout' in some way. If your ROMs are stored on a network drive, accessing them may be slow if your network is slow. This one is outside the scope of Stella. Perhaps check your network settings, cables, etc to diagnose the problem.

Another frequent problem occurs specifically for Linux users with respect to sound servers. The audio library that Stella uses will try several sound devices in sequence until it finds one that works. If you're not using 'PulseAudio' or any other sound server, it can take up to 5 seconds or more before Stella realizes this. The easiest workaround is to specifically tell the audio system which device you'll be using. Place the following in your startup script:

  export SDL_AUDIODRIVER=alsa

Yet another problem is that you could have an obsolete '' file that is being read each time Stella starts. As Stella now has a built-in ROM properties database, you no longer need use an external one. Any external database will override the properties built into Stella, and will cause the application to start more slowly. Normally, your file will be quite small, and only contain changes for specific ROMs you're interested in. This means it will either be non-existent or a few kilobytes in size at most. If you find one that is over 400KB, then it's probably obsolete and should be edited down or removed entirely.

I've located some ROMs and can get them to start in Stella, but I don't know how to actually start/play the game.

There are several issues to consider. First, some games need to be 'started' with the Select or Reset button, while others may use the joystick fire button instead. These games start up in a sort of 'demo' mode and wait for you to indicate that you are ready to play the game. Now, which game requires which button(s) to be pressed (if any) leads to the second issue ...

There were manuals included with most games sold for the Atari 2600. These manuals will explain in detail how to start the game, how to play it, etc., and are available in the AtariAge manuals area. Explaining every single game out there is beyond the scope of the Stella project. In fact, most of us developers probably haven't even played every single game out there.

I can't seem to move around in a game, or I don't know what controllers are being used with it.

Most games use the standard joystick controllers. Every game that Stella knows about (in its internal database) includes information about the controller type, so you normally would never need to set it manually. Now, to see which controller a game is using, you can either look at 'Game Properties' in the user interface, or turn on 'ROM Info mode', which shows game snapshots and other useful information. And of course, you could read the manual for the particular game too.

OK, that's half the solution. The other half is knowing how the controller is 'mapped' to Stella (ie, which keyboard key, mouse button or gamepad button/axis corresponds to which event on a real system). For this, see the various mappings in the manual. The defaults mappings are usually fine, but Stella is very configurable, and these mappings can be changed to your own preferences. This is explained under 'Advanced Configuration' in the manual, and is beyond the scope of this FAQ.

There seems to be a 'deadzone' when using a Stelladaptor/2600-daptor(II) and real paddles in certain games when using Stella in Linux.

This problem is caused by SDL2 using 'evdev' joysticks by default, but not having the ability to actually change the deadzone. An external application has been developed, located at evdev-joystick.tar.xz, which will let you set the deadzone to 0 and have smoother paddle movement. Download this application, decompress it, and follow the included instructions.

I'm experiencing sound issues, and the emulation doesn't sound authentic compared to a real system.

Always make sure you try setting the sound 'fragment size' to 512 bytes before reporting this as a bug. In fact, try playing with the various options under 'Audio Settings' to see if it makes any difference as well.

I'm experiencing sound issues, sound only works with the first ROM accessed; after returning to the ROM launcher and starting another ROM, sound is disabled.

This bug has been fixed as of Stella version 3.5. Please upgrade if you haven't already done so. For reference, the original bug report is included below:

Based on feedback, this seems to happen in very specific circumstances: people using Windows with an ATI video card in OpenGL mode. I suspect it's a bug in either SDL or ATI drivers, but haven't been able to track it down yet. For now, the only workaround is to completely quit Stella and start it again (which admittedly makes the ROM launcher essentially useless).

I'm developing a new game or downloaded a homebrew ROM that uses a custom controller, and I can't get Stella to recognize it.

By default, Stella will use its internal database to determine what controller type to use for a ROM. If there is no entry, it will try to detect the controller by analyzing the ROM. This may fail for new ROMs that have been released since Stella was last updated. In this case, the default is to assume a joystick controller.

If you want something other than a joystick, then you'll have to add custom properties for the ROM. Go to Options -> Game Properties -> Controller, and change to the desired type. Then click 'OK'. These settings are now saved, and need not be entered again.

Note to developers: Each time you recompile your ROM, you're essentially creating what Stella considers a new ROM image. As such, the game properties you set previously won't work, and will have to be entered again. If you're doing this often (in an edit-compile-test situation), consider using commandline arguments to set the controller type, which is much faster than navigating the UI.

When Stella exits from fullscreen mode, the icons or windows on my desktop are re-arranged. Similarly, exiting from external 'frontends' sometimes causes the display to be repositioned/shifted.

This problem has been fixed in version 4.0, which uses SDL2 behind the scenes. Stella will now use the desktop resolution when switching to fullscreen mode, so a video mode change never actually happens.

What options should I use to get the most authentic emulation possible?

In my experience, using Direct3D/OpenGL rendering mode with vertical sync enabled will result in smooth graphical performance. Of course, this is only true if your system supports vertical sync, and in general is only useful on monitors with a 60Hz refresh rate (all current LCDs). Finally, there are some Blargg TV effects that you might find interesting. Overall, to get more authentic looking emulation video-wise, you need to use a hardware-accelerated video mode (Direct3D/OpenGL/ES). If your video card doesn't properly support hardware acceleration, consider upgrading it to one that does :)

In terms of sound, try setting the fragment size as small as possible while not introducing any distortion. The smaller the size, the more accurate the audio 'resolution'.

In terms of controllers, consider using actual 2600 controllers. Several options exist, such as the 2600-daptor, Stelladaptor, or Bliss-Box.