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Computing (FOLDOC) dictionary
Motorola 68020
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processor 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.