[W/K] :: Motorola 68020

  Motorola 68020
       
           A microprocessor from Motorola.  It was the
          successor to the Motorola 68010 and was followed by the
          Motorola 68030.  The 68020 has 32-bit internal and external
          data and address buses and a 256-byte instruction buffer,
          arranged as 64 direct-mapped 4-byte entries[?].
       
          The 68020 added many improvements to the 68010 including a
          32-bit ALU and external data bus and address bus, and
          new instrucitons and addressing modes.  The 68020 (and
          68030) had a proper three-stage pipeline.
       
          The new instructions included some minor improvements and
          extensions to the supervisor state, some support for
          high-level languages which didn't get used much (and was
          removed from future 680x0 processors[?]), bigger (32 x 32-bit)
          multiply and divide instructions, and bit field manipulations.
       
          The new adderessing modes added another level of indirection
          to many of the pre-existing modes, and added quite a bit of
          flexibility to various indexing modes and operations.
       
          The instruction buffer (an instruction cache) was 256
          bytes, arranged as 64 direct-mapped 4-byte entries.  Although
          small, it made a significant difference in the performance of
          many applications.
       
          The 68881 and the faster 68882 FPU chips could be used with
          the 68020.
       
          The 68020 was used in many models of the Apple Macintosh II
          series of personal computers and Sun 3 workstations.
       
          (2001-03-07)