Altirra 2.1 Test 12 is released. Altirra is an Atari 8 bit Emulator on the Windows/DOS platform. Altirra emulates several models of the 8-bit Atari computers. This includes the the 800, 800XL, and 130XE versions. It has a lot of options, and compatibility is decent especially given the emulator's early stages. It also supports some copy protected games properly in emulation.

Altirra 2.1 Test 12 Changelog:

Bugs Fixed: Disk: Fixed inverted write protect bit status. Disk: Attempted writes to a write protected disk now return errors instead of a NAK. Disk: Fixed command response when accessing a drive with no disk. Author's Comment: Fixes several disk drive issues, tunes the drive sounds a bit, and fixes the Dimension X regression. XEGS game ROM banking should be fixed now. DOS XE issue should be fixed now (was a problem with XF551 high speed I/O). Dimension X issue was due to a display list timing issue related to a jump instruction fix -- both cases should work now. CPU emulation speed should be cycle exact or very close to exact, certainly not off by an order of magnitude. The rule for performance is: anything done in a loop in BASIC is going to be dog slow, no exceptions. BASIC is itself an interpreter, and on top of that Atari BASIC is not a particularly fast one. The only way to get good performance for vertical sprite movement is to move the sprite data in assembly language, which means either calling an ML routine directly or aliasing the sprites on top of string buffers so you can move the sprites with Atari BASIC string commands.

Download: Altirra 2.1 Test 12
Source: Here