The original Cisco IOS ran on 68000 series processors which lacked an MMU. Even the later 68K models used an "embedded" version of a processor which did not hav

The original Cisco IOS ran on 68000 series processors which lacked an MMU. Even the later 68K models used an "embedded" version of a processor which did not have an MMU. For example, the Cisco 2500 used a 680EC30. Regular 68030s had MMUs, but the "EC" model did not. Later versions did run on MIPS though.