资料来源 : Free On-Line Dictionary of Computing

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)