Configuration System: Compatibility

Compatibility

This lets you control the level of backwards compatibility on your system.

On 26bit desktop versions of RISC OS Six you can leave the settings at their default (the same as shown in the image above). This will allow legacy tasks to run correctly. Each of the options controls one part of the Compatibility system as follows:

Provide Compatibility HAL
On 32bit versions of RISC OS Six this will provide a legacy HAL (Hardware Abstraction Layer) that will allow older applications to function under a compatibility layer. On 26bit versions of RISC OS Six this option will be greyed out.

Accept known obsolete formats
Allow files that do not have an AIF header, but that can be identified to run without further checks. For example 32bit applications generated by ABC (Acorn Basic Compiler).

Accept non-AIF compliant files
This allows RISC OS Six to accept files without a header. Headers have been mandated by Acorn and then 3QD Developments Ltd since 1996. Running non-headered files may cause system instability.

Accept files with an unsuitable 26/32 code flag
Files should have a header that includes a 26/32bit flag. This allows RISC OS to stop files that might crash the machine from running. For example running a file designed for a 26bit machine will fail on a 32bit machine and could cause the machine to crash.

Accept over-long files
Allows RISC OS to run files that have a longer length than that reported in their header.

Accept truncated files
Allows RISC OS to run files that have a shorter length than that reported in their header.

Accept files with bad debug descriptors
Allows RISC OS to run files with suspect debugging descriptors.

Accept unheadered Transient Utilities
Prevents inappropriate code from being executed and improves system stability. This will be greyed out on 26bit versions of RISC OS Six.

For any changes in the options to take effect you must click on Set. When you click Set a window similar to that below may be displayed, if any of the compatibility settings are relaxed (as in the picture above).

Warning for users

The compatibility settings for your machine will have been setup by your supplier. You should not alter these settings unless you are absolutely certain that you know what you are doing. If you alter these settings then you could prevent applications from loading and compromise system stability.

This documentation is copyright 3QD Developments Ltd 2013 and may not be reproduced or published in any form without the copyright holder's permission. RISC OS is subject to continuous development and improvement as such all information is provided by 3QD Developments Ltd in good faith and is believed to be correct at the time of publication E&OE. 3QD Developments Ltd cannot accept any liability for any loss or damage arising from the use of any information provided as part of the RISC OS Documentation.

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