Atari++ v1.71 is released. The Atari++ Emulator is a Unix based emulator of the Atari eight bit computers, namely the Atari 400 and 800, the Atari 400XL, 800XL and 130XE, and the Atari 5200 game console. The emulator is auto-configurable and will compile on a variety of systems (Linux, Solaris, Irix).

Its emulation features are stunning:
Cycle precise emulation; this includes correct emulation of horizontal kernels and programs that modify chip registers within a horizontal line. In a less technical language, software making use of advanced displaying techniques will be emulated correctly.
Emulation of an advanced 1050 disk drive including single, double and enhanced density. The emulator not only understands .atr and .xfd files, but comes with a mini-boot loader that allows you to boot from binary load files (.exe and .com).
Supports .gz compressed images, and .DCM disk images. No additional tools required to load these disks.
Precise emulation of ANTIC and GTIA graphics, including undocumented scrolling features, undocumented GTIA player/missile priorities and collision detection, and some other less known GTIA features. Color artifacting is also available.
Precise emulaton of POKEY sound, including "Software Speech", high-pass filters and POKEY hardware timer interrupts. An emulation of the console speaker is also included.
Precise emulation of the POKEY SIO (serial transfer) protocol, including the Atari "sound effects" on disk loading and some lesser known influences of serial transfer on the sound subsystem.
Pokey stereo hack ("Gumby") included in the emulation.
Emulates graphics output either thru X11, or the SDL library, including a screen snapshot feature, saving images as PGM, BMP or PNG.
Sound output is either emulated by the Open Sound System (OSS), the ALSA system, the SDL library, or by recording the sound samples into a WAV file in CD quality.
Cylce-precise 6502 emulation, including "extra-instructions" that are not documented in the 6502-manual, and also including all known hardware-bugs of the 6502.
Printer emulation thru standard LPR printer user interface.
Flicker-Fixer option for games that toggle palettes fast for more colors.
Emulation of color artifacts due to PAL color subsampling
Optional de-blocking filter for magnified output
Built-in Os emulation
Joystick, paddle and lightpen emulation by keyboard or mouse, or by standard analogue PC joysticks. A special home-made interface allows the connection of Atari digital joysticks by an additional joystick driver. Hence, you'll be able to play all your old games even with your digital joysticks.
Includes emulation of the Pokey POT reading mechanism.
Saves and loads machine states to save games in the middle of the game play, and allows to resume from that point later on.
Includes emulation of a variety of cartridge types, including 5200 games cartridges and Oss supercarts.
Effective emulation of 800XL/XE and cartridge bank-switching mechanisms.
Emulation of the Atari 850 Interface box by the serial port of the host computer, including a full 850 driver "in ROM".
Interfaces to "Hias'" AtariSIO driver, allowing you to connect real Atari hardware to the PC.
Includes a Dos 2.xx compatible interface to the filing system of the emulator.
Easy to use graphical user front-end for simple setup and configuration, includes saving and loading of (human-readable) configuration files. The user front-end also allows to setup details like the player/missile collision setup to build "game-trainers" on demand.
Includes a built-in monitor allowing experts to debug Atari software easily.
And the best: It is free.

Atari++ v1.71 Changelog:

a new release of Atari++, the portable atari emulator for Linux and windows has been released here in the download section - as usual, you find there the Linux sources and a compiled version for 32-bit Windows. This release is how 1.70 should have been, but wasn't due to time constraints. Lots of fixes left over from 1.70 are now integrated, and regressions have been fixed: The ANTIC logic to roll over an instruction to the next scan was partially broken and also rolled a "Jump on Vertical Blank" over, breaking some games that played tricks with the DMA control register. The new CPU logic to fetch the wrong interrupt vector (NMI instead of IRQ) was partially broken and forgot to fetch the right high-bit, potentially breaking code. The 65C02 BRK instruction was emulated incorrectly. The NMOS version worked fine, and continues to work fine. 1.70 had, as indicated, a regression for late writes on Antic CHARCTL that broke at least one game ("Summer Games"). The corresponding logic has been re-done in a much cleaner way and is now part of 1.71. Pokey lo-byte timer registers in a 16-bit timer pair did not underrun to 255 correctly. In fact, the timer emulation was partially re-done and should now do correctly, including the relative offset of low and high-timer on a STIMER resynchronization. GTIA priority logic for player 4 on top of playfield 0/1 was broken in one priority selection, which got fixed now. Player/missile retriggering was partially incorrect. This has been fixed now. Player/missile resizing was, as stated, experimental in 1.70 and is now implemented correctly. On-line player/missile shape changes are now experimentally supported. The ANTIC/CPU WSYNC logic was partially broken as it does not block writes, only reads - the mechanism is a different one. Note that this only holds for the NMOS version. The CMOS version works correctly. This is also emulated. The NMI/IRQ reaction times were short by one cycle. They are now 7 cycles as indicated. GTIA mode 80 on top of a low-res screen created a wrong color for the PF3:BK pixel combination. This got fixed. GTIA VDelay support was partially broken. Actually, the P/M DMA engine was redesigned for this release and should now work correctly. Alsa sound support was broken on some hardware. For some Alsa drivers, audio hardware reacts allergic when trying to fill more samples into the available buffer, stalling the main program. The updated Alsa sound support rounds the samples written to the Alsa buffer to entire fragment sizes avoiding this problem. The SDL or Oss/HQOss drivers were not affected, though in general Alsa is preferably. Anti-News: (or, what does not yet work): P/M shape changes are currently supported experimentally until I get hands on real hardware. P/M shift-register disable tricks with PSIZE=2 are currently not supported. Writes to GTIA color or priority registers are not delayed and happen immediately. The same goes to many other registers in Pokey, Antic and PIA. Antic DMACtrl in-line adjustment tricks are not supported, neither any HScroll adjustments to disable the DMA-stop. Bus noise picked up by GTIA if GRACTL is enabled but DMACTL is disabled is currently not emulated correctly. Bus noise picked up by ANTIC on the right side of wide playfield screens is currently not emulated at all (and neither visible if it would). The POKEY soft-reset cylce is currently not emulated completely. Bit-banging serial output is currently not emulated at all.

Download: Atari++ v1.71
Source: Here