68010 with a
custom paged MMU. In a slightly different configuration,
the 3b1 was also known as the 7300.
It was also known as the Unix PC". AFIK the only difference between
the 7300 and 3B1 was the larger capacity hard drive.
Fortunately the interface is standard ST506. When I got my 7300, the first
thing I did was put in a half-height 40MB drive. The smaller drive is pretty
constraining with newer versions of the OS, especially in you've got add-ons.
Eric