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MOTOROLA M68040 USER’S MANUAL D- 1
APPENDIX D
M68000 FAMILY SUMMARY
This appendix summarizes the characteristics of the microprocessors in the M68000
family. The M68000PM/AD,
M68000 Family Programmer's Reference Manual,
includes
more detailed information on the M68000 Family differences.
Attribute MC68000 MC68008 MC68010 MC68020 MC68030 MC68040
Data Bus Size (Bits) 16 8 16 8, 16, 32 8, 16, 32 32
Address Bus Size (Bits) 24 20 24 32 32 32
Instruction Cache (In Bytes) 3* (Words) 256 256 4096
Data Cache (In Bytes) 256 4096
*The MC68010 supports a three-word cache for the loop mode.
Coprocessor Interface
MC68000, MC68008, MC68010 Emulated in Software
MC68020, MC68030 In Microcode
MC68040 Emulated in Software (On-Chip Floating-Point Unit)
Word/Long-Word Data Alignment
MC68000, MC68008, MC68010 Word/Long-Word Data, Instructions, and Stack
Must Be Word Aligned
MC68020, MC68030, MC68040 Only Instructions Must Be Word Aligned
(Data Alignment Improves Performance)
Control Registers
MC68000, MC68008 None
MC68010 SFC, DFC, VBR
MC68020 SFC, DFC, VBR, CACR, CAAR
MC68030 SFC, DFC, VBR, CACR, CAAR, CRP, SRP, TC, TT0,
TT1, MMUSR
MC68040 SFC, DFC, VBR, CACR, URP, SRP, TC, DTT0, DTT1,
ITT0, ITT1, MMUSR
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