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6.3.5.3
Special Addressing Modes
The special addressing modes do not use specific registers to specify an effective
address. These modes specify the operand or the operand address in a field of the
instruction, or they implicitly reference an operand. Figure examples are given for each of
the special addressing modes discussed in the following paragraphs.
6.3.5.3.1
Immediate Data
Classified as a program reference, this addressing mode requires one word of instruction
extension containing the immediate data. Figure 6-7 shows three examples. Example A
moves immediate data to register A0 without affecting A1 or A2. Examples B and C zero
fill register A0 and sign extend register A2
6.3.5.3.2
Absolute Address
This addressing mode requires one word of instruction extension containing the absolute
address. Figure 6-8 shows that MOVE Y:$5432,B0 copies the contents of address $5432
into B0 without changing memory location $5432, register B1, or register B2. This
addressing mode is classified as both a memory reference and program reference. The
16-bit absolute address is stored in the 16 LSBs of the extension word; the eight MSBs
are zero filled.
6.3.5.3.3
Immediate Short
The 8- or 12-bit operand, which is in the instruction operation word, is classified as a pro-
gram reference. The immediate data is interpreted as an unsigned integer (low-order
portion) or signed fraction (high-order portion), depending on the destination register. Fig-
ure 6-9 shows the use of immediate short addressing in four examples.
6.3.5.3.4
Short Jump Address
The operand occupies 12 bits in the instruction operation word, which allows addresses
$0000–$0FFF to be accessed (see Figure 6-10). The address is zero extended to 16 bits
MOTOROLA
INSTRUCTION FORMATS
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INSTRUCTION SET INTRODUCTION
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