MC68HC05P9A Datasheet, PDF (34/158 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
CPU
Instruction Set
The MCU instruction set has 62 instructions and uses eight addressing
modes. The instructions include all those of the M146805 CMOS Family
plus one more: the unsigned multiply (MUL) instruction. The MUL
instruction allows unsigned multiplication of the contents of the
accumulator (A) and the index register (X). The high-order product is
stored in the index register, and the low-order product is stored in the
accumulator.
Addressing Modes
The CPU uses eight addressing modes for flexibility in accessing data.
The addressing modes provide eight different ways for the CPU to find
the data required to execute an instruction. The eight addressing modes
are:
• Inherent
• Immediate
• Direct
• Extended
• Indexed, no offset
• Indexed, 8-bit offset
• Indexed, 16-bit offset
• Relative
Inherent
Inherent instructions are those that have no operand, such as return
from interrupt (RTI) and stop (STOP). Some of the inherent instructions
act on data in the CPU registers, such as set carry flag (SEC) and
increment accumulator (INCA). Inherent instructions require no operand
address and are one byte long.
Immediate
Immediate instructions are those that contain a value to be used in an
operation with the value in the accumulator or index register. Immediate
instructions require no operand address and are two bytes long. The
opcode is the first byte, and the immediate data value is the second byte.
12-hc05cpu
34
CPU
MOTOROLA
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