Central Processor Unit (CPU)
Technical Data MC68HC908AB32 — Rev. 1.0
96 Central Processor Unit (CPU) MOTOROLA
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
7.5 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.
7.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption
standby modes.
7.6.1 Wait Mode
The WAIT instruction:
• Clears the interrupt mask (I bit) in the condition code register,
enabling interrupts. After exit from wait mode by interrupt, the I bit
remains clear. After exit by reset, the I bit is set.
• Disables the CPU clock
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