Motorola M68000 User Manual download pdf (Page 16)

Addressing Capabilities

MOTOROLA

M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL

2-9

2.2.7 Address Register Indirect with Index (8-Bit Displacement) Mode

This addressing mode requires one extension word that contains an index register indicator

and an 8-bit displacement. The index register indicator includes size and scale information.

In this mode, the operand is in memory. The operand’s address is the sum of the address

eight bits; and the index register’s sign-extended contents (possibly scaled). The user must

specify the address register, the displacement, and the index register in this mode.

INTEGERSIGN EXTENDED

SIGN-EXTENDED VALUE

SCALE VALUE

CONTENTS

7031

31 0

DISPLACEMENT

INDEX REGISTER

SCALE

OPERAND POINTER

EA = (An) + (Xn) + d

(d ,An, Xn.SIZE*SCALE)

110

REG. NO.

CONTENTS

GENERATION:

ASSEMBLER SYNTAX:

EA MODE FIELD:

EA REGISTER FIELD:

NUMBER OF EXTENSION WORDS:

ADDRESS REGISTER

MEMORY OPERAND

POINTS TO

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 91 92

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Motorola M68000 User Manual Page 16