Altirra vs Atari800MacX

Altirra is a Windows emulator for 8-bit Atari computers, covering the Atari 400/800, 1200XL, 600/800XL, 130XE, XEGS and 5200. It provides cycle-exact handling of documented hardware and models undocumented behavior, including DMA timing and undocumented 6502 instructions. Supported files include ATR, ATX, ATZ, DCM, XFD, PRO, ARC, BAS, ROM, BIN, A52, CAS and SAP. Reimplemented operating-system, BASIC and handler ROMs are included, while real Atari ROM images can be supplied for compatibility. The emulator models memory and cartridge expansions, PBI devices, modems and 65C02/65C816 accelerators. Disk options include accelerated loading, realistic timing, sounds and drive CPU emulation. Its debugger offers source stepping, breakpoints, watchpoints, history and profiling. Recording, a cheat trainer, disk browsing and text copy/paste are also included. Altirra is free under GPL version 2 for Windows 7 or later.

Atari800MacX is a free macOS application that emulates Atari 8-bit computers and the Atari 5200. It supports the Atari 400/800, 1200XL, XL/XE, XEGS and Atari 5200 systems, with cartridge and machine support, joystick input, full-screen or windowed display and hard-drive emulation. Save states and controller remapping are supported. A native Cocoa interface supplies preferences, menus, file associations and help, while libSDL is bundled in the application package. The emulator needs ROM image files from original Atari systems; those files are not included. Version 6.0.1 is the latest release listed, dated January 22, 2022, and requires OS X 10.12 or newer. Version 6.0.0 added support for ARM-based M1 Macs. Listed updates include synchronized sound, a graphical debugger, VAPI and PRO images, copy and paste, configuration files and a new hard-drive emulation scheme. Downloads include the application and source code. Development is described as sporadic due to work commitments.