Altirra

Free plan Windows

What Altirra is

Altirra is a free Windows emulator for 8-bit Atari computers, including the Atari 400/800, 1200XL, 600/800XL, 130XE, XEGS, and 5200. It aims for cycle-exact emulation of documented hardware and also models details such as precise DMA timing and undocumented 6502 instructions. It supports many disk and software formats, including ATR, ATX, XFD, ROM, BIN, A52, CAS, and SAP. Reimplemented OS, BASIC, and handler ROMs are included; real Atari ROM images can be used for greater compatibility. Emulated expansions include memory and cartridge hardware, PBI devices, modems, and 65C02/65C816 accelerators. Disk options include accelerated loading, realistic timing, drive sounds, and full drive CPU emulation. Its debugger offers source-level stepping, breakpoints, tracepoints, watchpoints, execution history, and profiling. Altirra also includes recording, a cheat trainer, and disk and text utilities. It is licensed under GPL version 2 and runs on Windows 7 or later, with x86/x64 and ARM64 builds. The author describes setup as involved, and users need their own Atari software.

Who it suits

Altirra suits Windows users who want to emulate Atari 8-bit systems or use an emulator debugger. It is aimed at users prepared to handle involved setup and supply their own Atari software.

What it does well

Emulates several Atari computer and console systems.
Includes reimplemented OS, BASIC, and handler ROMs.
Debugger includes watchpoints and profiling.
Supports audio and video recording.
Free under GPL version 2.

What to know first

Windows only.
Setup is described as involved.
Users need their own Atari software.

Plans

Plan	Billed and limits	Price
Altirra	GNU General Public License (GPL), version 2 · Windows 7 or later · x86/x64 or ARM64	Free

As virtualdub.org lists them, read 3 Oct 2026. The maker's own page has the final word.

Getting started

Visit the Altirra website.
Choose the x86/x64 or ARM64 Windows build that fits your system.
Install or run Altirra on Windows 7 or later.
Provide Atari software to use with the emulator.
Use included reimplemented ROMs or supply real Atari ROM images for greater compatibility.

Verdict

Altirra combines broad Atari system emulation with debugging and recording tools. Its setup demands and requirement for users to provide Atari software are important considerations.

Questions

How much does Altirra cost?

Altirra is free. Its listed plan is 0.00 USD.

Which systems and platforms does it support?

It emulates the Atari 400/800, 1200XL, 600/800XL, 130XE, XEGS, and 5200. It runs on Windows 7, 8, 8.1, 10, 11 or later; Windows RT is not supported.

Does Altirra require a BIOS?

No. Altirra includes reimplemented OS, BASIC, and handler ROMs. Real Atari ROM images can be used for greater compatibility.

Is Altirra open source?

It is licensed under GNU GPL version 2.

Does it support save states and controller remapping?

Yes, both save states and controller remapping are supported.

Do I need to provide Atari software?

Yes. The author says users need their own Atari software, and describes setup as involved.

Facts from Altirra's own pages

Accuracy: It provides cycle-exact emulation of documented hardware features and emulates undocumented behavior such as precise DMA timing and undocumented 6502 instructions. · virtualdub.org, 3 Oct 2026
Debugger: The debugger includes source-level stepping, conditional breakpoints and tracepoints, watchpoints, execution history, and profiling. · virtualdub.org, 3 Oct 2026
Disk drives: Disk-drive options include accelerated loading, realistic disk timing, drive sounds, and full drive CPU emulation. · virtualdub.org, 3 Oct 2026
Download architectures: The site offers x86/x64 and ARM64 binaries; the ARM64 build is for Windows 10 on ARM on Snapdragon 835 or higher. · virtualdub.org, 3 Oct 2026
Emulated systems: It emulates the Atari 400/800, 1200XL, 600/800XL, 130XE, XEGS, and 5200 systems. · virtualdub.org, 3 Oct 2026
Expansion emulation: It emulates hardware expansions including memory and cartridge expansions, PBI devices, modems, and 65C02/65C816 accelerators. · virtualdub.org, 3 Oct 2026
File formats: Supported image and software formats include ATR, ATX, ATZ, DCM, XFD, PRO, ARC, BAS, ROM, BIN, A52, CAS, and SAP. · virtualdub.org, 3 Oct 2026
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. · virtualdub.org, 3 Oct 2026
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. · virtualdub.org, 3 Oct 2026
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. · virtualdub.org, 3 Oct 2026
ROMs: Altirra includes reimplemented OS, BASIC, and handler ROMs, while real Atari ROM images can be used for greater compatibility. · virtualdub.org, 3 Oct 2026
System requirements: The listed operating systems are Windows 7, 8, 8.1, 10, 11 or later; Windows RT is not supported. · virtualdub.org, 3 Oct 2026
What it does: Altirra is an emulator for 8-bit Atari computers. · virtualdub.org, 3 Oct 2026

Where Altirra stands on Freedom251

Atari Emulators#7 of 25