MC68030RC33 Motorola, MC68030RC33 Datasheet - Page 57

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MC68030RC33

Manufacturer Part Number
MC68030RC33
Description
MC68030RC33ENHANCED 32-BIT MICROPROCESSOR
Manufacturer
Motorola
Datasheet
2.4.15 Program Counter Memory Indirect Preindexed Mode
This mode is similar to the memory indirect preindexed mode described in 2.4.10 Memory
Indirect Preindexed Mode, but the PC is used as the base register. Both the operand and
operand address are in memory. The processor calculates an intermediate indirect memory
address by adding the PC contents, a base displacement (bd), and the scaled contents of
an index register. The processor accesses a long word at that address and adds the optional
outer displacement (od) to yield the effective address. The value of the PC is the address of
the first extension word. The reference is a program space reference and is only allowed for
reads (refer to 4.2 Address Space Types).
In the syntax for this mode, brackets enclose the values used to calculate the intermediate
memory address. All four user-specified values are optional. However, the user must supply
the assembler notation ZPC (zero value is taken for the PC) to indicate that the PC is not
used. This allows the user to access the program space without using the PC in calculating
the effective address. Both the base and outer displacements may be null, word, or long
word. When a displacement is omitted or an element is suppressed, its value is taken as
zero in the effective address calculation.
GENERATION:
EA = (bd + PC + Xn . SIZE * SCALE) + od
ASSEMBLER SYNTAX:
([bd, PC, Xn. SIZE*SCALE],od)
MODE:
111
REGISTER FIELD:
011
PROGRAM COUNTER:
31
BASE DISPLACEMENT:
31
INDEX REGISTER
31
OUTER DISPLACEMENT:
EFFECTIVE ADDRESS:
NUMBER OF EXTENSION WORDS:
1, 2, 3, 4 OR 5
MOTOROLA
Data Organization and Addressing Capabilities
31
ADDRESS OF EXTENSION WORD
0
SIGN-EXTENDED VALUE
0
SIGN-EXTENDED VALUE
7
0
SCALE VALUE
31
INDIRECT MEMORY ADDRESS
31
VALUE AT INDIRECT MEMORY
ADDRESS IN PROGRAM SPACE
0
SIGN-EXTENDED VALUE
31
MC68030 USER’S MANUAL
0
+
+
X
0
POINTS TO
0
+
0
OPERAND
2-19

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