MC68030 Datasheet, PDF (44/602 Pages) Motorola, Inc – ENHANCED 32-BIT MICROPROCESSOR

Data Organization and Addressing Capabilities
The data types supported in memory by the MC68030 are bit and bit field data; integer data
of 8, 16, or 32 bits; 32-bit addresses; and BCD data (packed and unpacked). These data
types are organized in memory as shown in Figure 2–2. Note that all of these data types can
be accessed at any byte address.
Coprocessors can implement any data types and lengths up to 255 bytes. For example, the
MC68881/MC68882 floating-point coprocessors support memory accesses for quad-word-
sized items (double-precision floating-point values).
Figure 2A bit operand is specified by a base address that selects one byte in memory (the
base byte) and a bit number that selects the one bit in this byte. The most significant bit of
the byte is bit 7.
31
23
15
7
0
LONG WORD $00000000
WORD $00000000
WORD $00000002
BYTE $00000000
BYTE $00000001
BYTE $00000002
LONG WORD $00000004
BYTE $00000003
WORD $00000004
WORD $00000006
BYTE $00000004
BYTE $00000005
BYTE $00000006
BYTE $00000007
LONG WORD $FFFFFFFC
WORD $FFFFFFFC
WORD $FFFFFFFE
BYTE $FFFFFFFC
BYTE $FFFFFFFD
BYTE $FFFFFFFE
BYTE $FFFFFFFF
Figure 2-1. Memory Operand Address
2-6
MC68030 USER’S MANUAL
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