mc68hc08qa24 Freescale Semiconductor, Inc, mc68hc08qa24 Datasheet - Page 89

• Manufacturer Part Number: mc68hc08qa24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

MC68HC08QA24
Freescale Semiconductor
NOTE:
To maintain M68HC05 compatibility, the upper byte of the index register
(H) is not stacked automatically. If the interrupt service routine modifies
H, then the user must stack and unstack H using the push H onto stack
(PSHH) and pull H from stack (PULH) instructions.
N — Negative Flag Bit
Z — Zero Flag Bit
C — Carry/Borrow Flag Bit
After the I bit is cleared, the highest-priority interrupt request is
serviced first.
A return-from-interrupt (RTI) instruction pulls the CPU registers from
the stack and restores the interrupt mask from the stack. After any
reset, the interrupt mask is set and can be cleared only by the clear
interrupt mask software instruction (CLI).
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.
The CPU sets the zero flag when an arithmetic operation, logic
operation, or data manipulation produces a result of $00.
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 = Negative result
0 = Non-negative result
1 = Zero result
0 = Non-zero result
1 = Carry out of bit 7
0 = No carry out of bit 7
Central Processor Unit (CPU)
Central Processor Unit (CPU)
Technical Data
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