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2.6.4
Basic Instruction Formats
The H8S/2633 Series instructions consist of 2-byte (1-word) units. An instruction consists of an
operation field (op field), a register field (r field), an effective address extension (EA field), and a
condition field (cc).
(1) Operation Field: Indicates the function of the instruction, the addressing mode, and the
operation to be carried out on the operand. The operation field always includes the first four bits of
the instruction. Some instructions have two operation fields.
(2) Register Field: Specifies a general register. Address registers are specified by 3 bits, data
registers by 3 bits or 4 bits. Some instructions have two register fields. Some have no register
field.
(3) Effective Address Extension: Eight, 16, or 32 bits specifying immediate data, an absolute
address, or a displacement.
(4) Condition Field: Specifies the branching condition of Bcc instructions.
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