Atari800MacX!

WinUAE is a Windows port of the emulator UAE.

VICE is a program that runs on a Unix, MS-DOS, Win32, OS/2, Acorn RISC OS, BeOS, QNX 4.x, QNX 6.x, Amiga, GP2X, Dingoo, Syllable, SkyOS or Mac OS X machine and executes programs intended for the old 8-bit computers. The current version emulates the C64, the C64DTV, the C128, the VIC20, almost all PET models, the PLUS4 and the CBM-II (aka C610).

z26 -- An Atari 2600 Emulator

Hataroid is an Atari ST emulator for Android based on Hatari .

Javatari is a multiplayer Atari 2600 emulator written in pure Java with no external libs. Just open it! Needs Java 6 or greater and Atari ROMs.

The ProSystem Emulator is an Atari 7800 emulator for the PC and Windows OS. The emulator was written in C++ using the Windows API and DirectX. It emulates the Atari 7800 NTSC and PAL TV standards.

Steem is an open source Atari STE emulator for Windows and Linux. It runs almost every ST program ever made without any problems. Steem is designed to be easy to use and has many unique features. Whether you want to run great old games, use MIDI apps just like you did on the ST or you have some other, more sinister motive, Steem is the emulator for you!

jGameBase is a fully-­featured retro-gaming emu­lator frontend and game database utility. It is a sister app­lication to the Windows program GameBase (without "j"), the official frontend for the GB64 Collection.

Hatari is an Atari ST/STE/TT/Falcon emulator for GNU/Linux, BSD, Mac OS X, Windows and other systems which are supported by the SDL library.

WinFellow is a Commodore Amiga emulator that has high compatibility and supports all existing models.

Power20 is an emulator for the Commodore VIC-20. It allows you to run your favorite VIC-20 software on your Apple Macintosh (with PowerPC or intel-CPU) at full speed with smooth graphics and great sound.