[ekianjo]

AmigaOS did not have memory protection even in the later iterations post 68040 availability (A4000) - not sure about AmigaOS 4.x though.

[jug]

AmigaOS 4 does use the MMU, but only to map pages to virtual addresses to for example help with memory fragmentation and swapping to disk.

Here's some surprisingly thorough documentation on this:

http://wiki.amigaos.net/wiki/Exec_Memory_Allocation

However, the MMU is not used for memory protection, not even on Amiga OS 4.

Edit: OK, so not entirely true... See this for more: http://www.os4coding.net/forum/memory-protection-support

[mnw21cam]

If you were lucky enough to have an Amiga with a CPU that did have an MMU, you could use a piece of freely-downloadable software (called GigaMem) to implement paged virtual memory - albeit still with a single address space. One of those few operating systems that could have virtual memory implemented outside the OS kernel.