Motorola MC68030 User Manual page 44

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
BYTE $00000000
BYTE $00000004
WORD $FFFFFFFC
BYTE $FFFFFFFC
2-6
23
LONG WORD $00000000
WORD $00000000
BYTE $00000001
LONG WORD $00000004
WORD $00000004
BYTE $00000005
LONG WORD $FFFFFFFC
BYTE $FFFFFFFD
Figure 2-1. Memory Operand Address
MC68030 USER'S MANUAL
15 7
WORD $00000002
BYTE $00000002
WORD $00000006
BYTE $00000006
WORD $FFFFFFFE
BYTE $FFFFFFFE
0
BYTE $00000003
BYTE $00000007
BYTE $FFFFFFFF
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