Motorola 68030 (MC68030) is an enhanced version of
68020 microprocessor. The 68030 CPU has
32-bit address bus and can address up to 4 GB of physical memory.
Data bus width on the MC68030 is dynamic - the CPU can work with
8-bit, 16-bit and 32-bit data buses. Both data and address buses can
run in new synchronous mode - in this mode data transfer time is
reduced up to 33% (from 3 clock cycles to 2 clock cycles). If
desired, the 68030 can be switched back to asynchronous mode.
Another new bus mode is a burst memory mode. In this mode the bus can
transfer up to 4 long words (16 bytes of data) with average transfer
time 1 clock cycle per long word. The 68030 integrates modified
version of MC68851 Paged Memory Management Unit (PMMU). To control
integrated PMMU the CPU has 4 new instructions.
The MC68030 has better performance than the 68020 due to a few core
enhancements:
- The CPU has additional 256-byte data cache with one clock access
time.
- Access time for the instruction cache was reduced by 50% - from two
to one clock cycle.
- New burst memory interface can be used to quickly fill-in data and
instruction caches.
- On-chip MMU can perform address translation in parallel to other
CPU functions.
Like the 68020 microprocessor, the 68030 supports
Motorola 68881 and
68882 co-processors.
Motorola also produced 68EC030 (MC68EC0300 - embedded version of the 68030
microprocessor. The 68EC030 doesn't have integrated memory management
unit, all other features of the 68EC030 are the same as for Motorola
68030.
Some Motorola 68030 and 68EC030 microprocessors were marked with custom
part numbers. To identify these processors please see
List of Motorola custom part numbers.
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