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SPECIFICTION
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Altirra

virtualdub.org

Free plan Windows
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Spec score 7.8 #8 of 25 in Atari Emulators

What it is

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.

Spec sheet

What it does
Altirra is an emulator for 8-bit Atari computers.Read 3 Oct 2026 · virtualdub.org
Accuracy
It provides cycle-exact emulation of documented hardware features and emulates undocumented behavior such as precise DMA timing and undocumented 6502 instructions.Read 3 Oct 2026 · virtualdub.org
Debugger
The debugger includes source-level stepping, conditional breakpoints and tracepoints, watchpoints, execution history, and profiling.Read 3 Oct 2026 · virtualdub.org
Disk drives
Disk-drive options include accelerated loading, realistic disk timing, drive sounds, and full drive CPU emulation.Read 3 Oct 2026 · virtualdub.org
Download architectures
The site offers x86/x64 and ARM64 binaries; the ARM64 build is for Windows 10 on ARM on Snapdragon 835 or higher.Read 3 Oct 2026 · virtualdub.org
Emulated systems
It emulates the Atari 400/800, 1200XL, 600/800XL, 130XE, XEGS, and 5200 systems.Read 3 Oct 2026 · virtualdub.org
Expansion emulation
It emulates hardware expansions including memory and cartridge expansions, PBI devices, modems, and 65C02/65C816 accelerators.Read 3 Oct 2026 · virtualdub.org
File formats
Supported image and software formats include ATR, ATX, ATZ, DCM, XFD, PRO, ARC, BAS, ROM, BIN, A52, CAS, and SAP.Read 3 Oct 2026 · virtualdub.org
License and affiliation
Altirra is licensed under GPL version 2, and the author states that neither the author nor the software is affiliated with Atari.Read 3 Oct 2026 · virtualdub.org
Notable limitation
The author says Altirra is designed as a system emulator and debugger, and that setup is involved; users need their own Atari software.Read 3 Oct 2026 · virtualdub.org
Recording and utilities
Features include audio and video recording, a cheat trainer, a DOS disk explorer with drag-and-drop, and text mode copy/paste.Read 3 Oct 2026 · virtualdub.org
ROMs
Altirra includes reimplemented OS, BASIC, and handler ROMs, while real Atari ROM images can be used for greater compatibility.Read 3 Oct 2026 · virtualdub.org
System requirements
The listed operating systems are Windows 7, 8, 8.1, 10, 11 or later; Windows RT is not supported.Read 3 Oct 2026 · virtualdub.org

Plans and prices

Altirra Free GNU General Public License (GPL), version 2 · Windows 7 or later · x86/x64 or ARM64 Read 3 Oct 2026 · virtualdub.org

Every Altirra plan and price →

Strong points and limits

Strong points

  • Cycle-exact and undocumented hardware emulation
  • Supports six Atari computer and console systems
  • Debugger includes stepping, breakpoints and profiling
  • Audio and video recording included
  • Free GPL version 2 license

Limits

  • Windows only
  • Setup is described as involved
  • Users must provide their own Atari software
  • Windows RT is not supported

Who it suits

It suits people emulating Atari 8-bit systems on Windows, including users who need debugging, expansion emulation or detailed hardware behavior. Setup is involved, and users need their own Atari software.

Verdict

Altirra combines broad Atari system coverage with detailed emulation and debugging tools. Its Windows-only availability and involved setup matter when planning an installation.

Where Specifiction places it

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