Freescale Semiconductor, Inc.
Central Processor Unit (CPU)
Arithmetic/Logic Unit (ALU)
N — Negative Flag
The CPU sets the negative flag when an arithmetic operation, logic
operation, or data manipulation produces a negative result, setting bit
7 of the result.
1 = Negative result
0 = Non-negative result
Z — Zero Flag
The CPU sets the zero flag when an arithmetic operation, logic
operation, or data manipulation produce a result of $00.
1 = Zero result
0 = Non-zero result
C — Carry/Borrow Flag
The CPU sets the carry/borrow flag when an addition operation
produces a carry out of bit 7 of the accumulator or when a subtraction
operation requires a borrow. Some instructions — such as bit test and
branch, shift, and rotate — also clear or set the carry/borrow flag.
1 = Carry out of bit 7
0 = No carry out of bit 7
5.5 Arithmetic/Logic Unit (ALU)
The ALU performs the arithmetic and logic operations defined by the
instruction set.
Refer to the CPU08 Reference Manual, Motorola document order
number CPU08RM/AD, for a description of the instructions and
addressing modes and more detail about the architecture of the CPU.
5.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low
power-consumption standby modes.
MC68HC908RFRK2
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Central Processor Unit (CPU)
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