Motorola MC68030 User Manual page 69

Single Effective Address Instruction Format
15 14 13 12 11 10 9 8 7 6 5
EFFECTIVE ADDRESS
MODE
REGISTER
Brief Format Extension Word
15 14
12 11 10 8
DIA REGISTER WIL
SCALE
I
0
I
DISPLACEMENT
Full Format Extension Word(s)
15 14 12 11 10
9 8
7
6
5
DIA
I
REGISTER
I
WIL
I
SCALE
I
1
I
BS
I
IS
I
BD SIZE
I
o
I
IllS
BASE DISPLACEMENT (0, I, OR 2 WORDS)
OUTER DISPLACEMENT (0, I, OR 2 WORDS)
Field Definition
Field
Definition
Instruction:
BS Base Register Suppress:
Register General Register Number
0= Base Register Added
Extensions:
1 = Base Register Suppressed
Register
Index Register Number
IS Index Suppress:
0= Evaluate and Add Index
D/A Index Register Type
Operand
O=Dn
1 = Suppress Index Operand
1 =An
W/L Word/Long-Word Index Size
BD SIZE Base Displacement Size:
00 = Reserved
0= Sign-Extended Word
01 = Null Displacement
1 = Long Word
10 = Word Displacement
Scale Scale Factor
11 = Long Displacement
00=1
01 =2
illS Index/Indirect Selection:
10=4
Indirect and Indexing Operand
11 =8
Determined in Conjunction with
Bit 6, Index Suppress
Figure 2-4. Effective Address Specification Formats
Effective address modes are grouped according to the use of the mode. They
can be classified as follows:
Data A data addressing effective address mode is one that refers to
data operands.
Memory A memory addressing effective address mode is one that refers
to memory operands.
Alterable An alterable addressing effective address mode is one that refers
to alterable (writable) operands.
Control
MOTOROLA
A control addressing effective address mode is one that refers
to memory operands without an associated size.
MC68030 USER'S MANUAL 2-23