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This is the R.O.M.E.68000 Manual version 0.51.
This is an experimental version.
Copyright © 1997 by G. Mezzetti; last update: January 1, 1999.

Chapter II
Addressing Modes

We saw in Chapter I that in the instructions of the ``Control'' class (which are the ``normal'' ones) 4 bits are set aside for each operand to hold the key that codifies the addressing mode for that operand; this give us the possibility to have up to 15 modes, since one key (namely, 0) ought to be reserved to indicate an unused operand. As a matter of fact, 13 modes are defined in the R.O.M.E.68000, some of which come in two varieties for the two classes of instructions, giving a total of 18 variation keys. You'll learn everything about them in this chapter.

Contents of This Chapter

1. List of All Addressing Modes
2. How Pictures Are Drawn
3. Much More About Registers
4. When Registers Are Not Being Used
5. Elementary Components of Addresses
6. Recapitulation of the Rules About Unused Fields
7. Abbreviations for Syntax
8. Description of 4-Bits Modes
9. Description of 3-Bits Modes
10. Description of 2-Bits Modes
11. A Word About Increments and Decrements
12. Addressing Groups

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