# Altirra ROM set

Copyright © 2016 Avery Lee, All Rights Reserved.

Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. This file is offered as-is, without any warranty.

This ROM set consists of the following four files:

- atbasic.rom (Altirra 8K BASIC)
- altirraos-800.rom (AltirraOS for 400/800 Computers)
- altirraos-xl.rom (AltirraOS for XL/XE/XEGS Computers)
- altirraos-5200.rom (AltirraOS for 5200 SuperSystem)

These are replacements for the standard Atari ROMs that would normally be present in these systems; they are not the original ROMs, but new ones rewritten from scratch to match the same programming interface without the original code. They may be used in either real hardware or in emulators with sufficient accuracy. The mapping to standard filenames expected by most emulators is as follows:

- atbasic.rom -> ATARIBAS.ROM
- altirraos-800.rom -> ATARIOSB.ROM
- altirraos-xl.rom -> ATARIXL.ROM / ATARIXEGS.ROM
- altirraos-5200.rom -> ATARI5200.ROM

Please note: The replacement ROMs have been written to support software that conforms to Atari's original specifications for usage of public variables and entry points into the firmware ROMs. Software that makes use of undocumented entry points or behaviors from the original OS and BASIC ROMs may not work with these ROMs. An attempt has been made to achieve reasonably high compatibility, but some programs have hardcoded assumptions that cannot work with such a replacement ROM and will only run on the original firmware.

The license for all files is the all-permissive license as shown at the top of this page.

The source code for these files is included in the source of the Altirra emulator.