

The original Mac II had an Apple MMU chip installed which performs a subset
of the 68851's functions.  If you look underneath your front left floppy
bay you will find three chips, all approximately the same size.  One will
be the 68020, the next the 68881, and the third, approximately the same
size, will be the Apple chip.  It is easy to spot because it has a 'hump'
in the middle of it.


Example:


                         -----------
                        /           \
         ---------------             ---------------
         |                                         |
         |                                         |

That and the Apple logo should make it easy to find.