Altirra vs Test7800

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.

Test7800 is an experimental Atari 7800 emulator for playing many available 7800 ROM files. It supports flat .a78 ROMs, several bankswitching SuperGame ROMs, and ELF cartridges with an embedded ARM chip. Its emulation includes 6502, TIA, RIOT, and ARM components taken from Gopher2600; the MARIA implementation is new to this project. POKEY and many of its layouts are supported. Players can use a keyboard or gamepad, with a mouse for paddle and trackball input. QuadTari mode supports up to four joystick players, with assignments configurable through -players. An optional overlay displays MARIA state, and the -tv option selects PAL instead of the default NTSC BIOS. Test7800 is available for Linux, macOS, the web, and Windows, and is published under GPL-3.0. The project describes itself as incomplete: important features are missing, and some conglomerate cartridge hardware configurations are not emulated. Its basic command-line debugger lacks many features, and performance was not a design focus. Occasional nightly builds are distributed as prereleases.