A8DS v3.6a is released. A8DS is an Atari 8-bit computer emulator. Specifically, it targets the 800XL / 130XE systems and various hardware extensions to increase the memory. The stock 800XL had 64KB of RAM. The default A8DS configuration is an XL/XE machine with 128KB of RAM which will run most of the 8-bit library. A8DS goes beyond the normal XL/XE 128K machine and provides three alternative configurations: the 320K (RAMBO) and 1088K for a few large games and demos plus an Atari 800 (non-XL) 48K machine for backwards compatibility with some older games that don't play nice with a more "modern" XL/XE setup. As such, it's really grown to be a full-featured 8-bit emulator to run nearly the entire 8-bit line up of games on their Nitendo DS/DSi handhelds.
The emulator comes "equipped" with the ability to run executable images or disk images which are the two most popular types. It does not support cart types yet. Virtually everything that can be run on an 8-bit system has been converted into an Executable image (.xex) or a Disk image (.atr) and, unlike cart ROM images, there is no complicated setup to pick the right banking setup. The goal here is to make this as simple as possible - point to the executable 8-bit Atari image you want to run and off it goes!

A8DS Features
Most things you should expect from an emulator. Games generally run full-speed with just a handful of exceptions. If you load a game and it doesn't load properly, just load it again or hit the RESET button which will re-initialize the A8DS machine. If a game crashes, you will get a message at the bottom of the screen after loading - a crash usually means that the game requires the BASIC cart to be inserted and you can toggle that when loading a game (or using the GEAR icon). Not every game runs with this emulator - but 99% will. I'll try to improve compatibilty as time permits.
The emulator supports multi-disk games. When you need to load a subsequent disk for a game, just use the Y button to disable Boot-Load which will simply just insert the new disk and you can continue to run. Not all games will utilize a 2nd disk drive but D2: is available for those games that do. It's handy to have a few blank 90K single-sided disks available on your setup which you can find easily online - these can be used as save disks.
The .ATR disk support handles up to 360K disks (it may work with larger disks, but has not been extensively tested beyond 360K).
The emulator has the built-in Altirra BASIC 1.55 which is a drop-in replacement for the Atari Basic Rev C (only more full-featured). Normally you can leave this disabled but a few games require the BASIC cart be present and you can toggle this with the START button when you load a game. If you try to load a game and it crashes, most likely you need to have BASIC enabled. Most games don't want it enabled so that's the default. If you want to play around with BASIC, enable the BASIC cart and pick a DOS disk of some kind to get drive support and you can have fun writing programs. Be aware that the Altirra BASIC is faster than normal ATARI BASIC and so games might run at the wrong speed unless you're using the actual ATARI REV C rom.

A8DS Changelog:
Hotfix for state save/restore. Sorry!
Added ability to map Joystick 2 so you can play twin-stick games like Robotron and Space Dungeon.
Added 64K memory option and put all memory options in the correct order.

Download:A8DS v3.6a
Source:Here