Stella v5.0 is released. Stella is a multi-platform Atari 2600 VCS emulator. The Atari 2600 Video Computer System (VCS), introduced in 1977, was the most popular home video game system of the early 1980's. Now you can enjoy all of your favorite Atari 2600 games on your PC thanks to Stella!

Stella v5.0 changelog:
Note: because of major TIA/6502/RIOT changes, the state file format has changed, and old state files will not work with this release.
Stella has moved from Sourceforge to Github.
Completely new TIA core is now available, ported from 6502ts by Christian Speckner (DirtyHairy). This new core is extremely accurate, and matches real hardware in almost every test we've performed. New features include:

Meltdown emulates correct
The lap number in Pole Positions displays correctly
Artifacts in the mountains on Snoopy and the Red baron are gone
Line artifacts in Title Match Pro Wrestling and Realsports Boxing are fixed
The spurious line at the left border of Video Chess now displays correctly
All 32 char text demos from AtariAge now work perfectly (Stella 4 shows artifacts on several of these)
Stella is now the only emulator to display the "Mega Bitmap Demo" (atext.bin) from AtariAge correctly
Improved starfield effect for missiles (still TODO for ball and players)
RSYNC emulation has improved, all testcases now match real hardware
Several other ROMs that have never worked in any emulator are now emulated correctly
RDY behavior with respect to write cycles is accurate
Optional YStart autodetect and more robust frame handling
NUSIZ during player draw matches hardware
RESMx during missile draw matches hardware
Paddle emulation is slightly more accurate. As a consequence, the "paddle feel" may be slightly different from Stella 4
Fixed debug colors can now be set for each graphical object, from a choice of 'red', 'orange', 'yellow', 'green', 'blue' and 'purple'. This is accessible through the new 'tia.dbgcolors' commandline argument and within the UI.
Implemented new phosphor emulation mode, which is much closer to real TV output. Related to this, added ability to change the default phosphor blend level in the UI and through the new 'tv.phosblend' commandline argument. Special thanks to Thomas Jentzsch for the idea and implementation.
TV phosphor effect can now be force-enabled for all ROMs, instead of manually setting ROM properties for each ROM. This is accessible in the UI and through the 'tv.phosphor' commandline argument, and defaults to being off (or enabled per-ROM).
PAL color-loss and Blargg TV effects can now be enabled at the same time. Previously, when Blargg effects were enabled, PAL color-loss couldn't be shown. Related to this, the Blargg effects now use much less memory and in some cases run faster than before.
Much improved RIOT timer emulation never before seen in any emulator. Special thanks to Christian Speckner (DirtyHairy) for the implementation, and alex_79 for finding documentation that finally describes in more detail how the M6532 chip actually works.
Added BUS (experimental) and CDF bankswitching schemes, and also ARM Timer 1 support; special thanks to SpiceWare for the code.
Fixed bug with SaveKey and AtariVox not properly closing their memory files before starting another instance of the same ROM, when the ROM was opened in the ROM launcher.
Various improvements to the debugger and command prompt:

The 'cls' command now only clears the screen, not the history
The 'help' command now accepts other commands, and gives extra
information about the command (ie, 'help breakif' prints extended information about the breakif command)
Added 'palette' command, which shows a color swatch of the currently active TIA palette
Added 'debugcolors' command, which shows a legend for 'fixed debug colors' mode
The previous trap'm' commands now work when setting TIA read addresses; previously they only worked for write addresses
The previous trap'm' commands are now renamed 'trap', 'trapread' and 'trapwrite'
The TIA tab now shows 'old' contents of player and ball registers
Various UI items are crossed out when disabled, to more clearly indicate their current state
Various UI items that previously required a double-click to toggle (pixel and bit widgets) now require only a single-click.
Command completion now works with internal functions and pseudo-ops (basically, anything starting with the '_' character)
System labels (aka, register names, etc) can now be typed in lowercase. Previously, these labels always had to be uppercase.
In general, input error checking is much more strictly enforced
Read-only UI items now have a different background color, to clearly indicate if an item can be modified.
Debugger '.lst' and '.sym' files are now searched based on the name of the ROM file, and not on the internal properties name.
Snapshots can now be saved by pressing the F12 key (the various other ways to save snapshots still exist).
Mouse grabbing is now enabled in windowed mode only when the ROM is using a virtual analog controller (paddles, trakball, etc).
Renamed various trakball-like controllers more accurately: AmigaMouse, AtariMouse (previously CX80) and Trakball (previously CX22). Related to this, reduced the resolution of the Trakball by half, to properly match real hardware.
The stack pointer (SP) is now initialized to $FD instead of $FF, to match research done in other 6502 projects.
Fixed bug in debugger tracing and displaying the partial TIA image; the first time entering the debugger and starting to trace, the image was blanked out (black) instead of being drawn in greyscale. Also, the image is now synchronized, instead of being two frames behind.
Fixed crash with zipped ROMs that are less than 4K in size; so far this bug has only ever occurred in Windows XP, but it's been there since Stella 4.1.
Fixed bug in 'Rom Audit' functionality; sometimes ROMs without a valid properties entry were being renamed as "Untitled.bin".
For the entire UI, removed colons and generally made the UI items easier to read.
When in 'ROM launcher mode', Stella now uses slightly less CPU time. More work is required in this area, though.
Added ROM properties for D.K. VCS homebrew ROM, thanks to Andreas Dietrich.
Added slight improvement for auto-detecting Superchip bankswitching; the new implementation now works for the NTSC 'Dig Dug' ROM. Special thanks for SpiceWare for the idea and modified implementation.
Fixed long-standing bug in 3-voice music in DPC+ bankswitching scheme; the music now sounds much more like the real thing.
For the Linux/UNIX port:

The settings directory now uses the XDG Base Directory Specification. In most cases, this means that your files will now be stored in '$HOME/.config/stella' instead of '$HOME/.stella'. To keep your old settings, run the following commands from the terminal:
cd ~
mv .stella .config/stella
You will probably need to edit '~/.config/stella/stellarc' and change some paths accordingly.

For the OSX port:

Always use the built-in png and zlib libraries instead of the system versions.
The preferences file has changed from 'net.sourceforge.Stella.plist' to 'Stella-emu.plist'. To keep your old settings, run the following commands from the terminal:
cd ~/Library/Preferences
mv net.sourceforge.Stella.plist Stella-emu.plist

Updated internal ROM properties database to ROM-Hunter version 13 (thanks go to RomHunter for his tireless research in this area). Related to this, updated the snapshot collection.
Updated included PNG and ZLIB libraries to latest stable version. Also, both libraries are now compiled into the app whenever one is selected. This fixes issues with a newer ZLIB not working with an older PNG, etc.
Updated build scripts for Visual Studio 2017 (Windows) and MacOS Sierra (latest version of Xcode), and make these the minimum supported versions for building Stella.
Updated UNIX configure script to work with the clang 5+ and gcc 7+ compiler versions, and fixed compile issues on AArch64 and ppc64le architectures.

Download: Stella v5.0
Source: Here