Holtek HT66F488 Manual page 30

• AC is set if an operation results in a carry out of the low nibbles in addition, or no borrow from
the high nibble into the low nibble in subtraction; otherwise AC is cleared.
• Z is set if the result of an arithmetic or logical operation is zero; otherwise Z is cleared.
• OV is set if an operation results in a carry into the highest-order bit but not a carry out of the
highest-order bit, or vice versa; otherwise OV is cleared.
• PDF is cleared by a system power-up or executing the "CLR WDT" instruction. PDF is set by
executing the "HALT" instruction.
• TO is cleared by a system power-up or executing the "CLR WDT" or "HALT" instruction. TO is
set by a WDT time-out.
In addition, on entering an interrupt sequence or executing a subroutine call, the status register will
not be pushed onto the stack automatically. If the contents of the status registers are important and if
the subroutine can corrupt the status register, precautions must be taken to correctly save it.
STATUS Register
Bit 7
�a�e SC
R/W R/W
POR x
Bit 7 SC: The result of the "XOR" operation which is performed by the OV flag and the
MSB of the instruction operation result.
Bit 6 CZ: The the operational result of different flags for different instructions.
For SUB/SUBM/LSUB/LSUBM instructions, the CZ flag is equal to the Z flag.
For SBC/SBCM/LSBC/LSBCM instructions, the CZ flag is the "AND" operation
result which is performed by the previous operation CZ flag and current operation zero
flag.
For other instructions, the CZ flag will not be affected.
Bit 5 TO: Watchdog Time-Out flag
0: After power up or executing the "CLR WDT" or "HALT" instruction
1: A watchdog time-out occurred.
Bit 4 PDF: Power down flag
0: After power up or executing the "CLR WDT" instruction
1: By executing the "HALT" instruction
Bit 3 OV: Overflow flag
0: No overflow
1: An operation results in a carry into the highest-order bit but not a carry out of the
Bit 2 Z: Zero flag
0: The result of an arithmetic or logical operation is not zero
1: The result of an arithmetic or logical operation is zero
Bit 1 AC: Auxiliary flag
0: No auxiliary carry
1: An operation results in a carry out of the low nibbles in addition, or no borrow
Bit 0 C: Carry flag
0: No carry-out
1: An operation results in a carry during an addition operation or if a borrow does
C is also affected by a rotate through carry instruction.
Rev. 1.21
6 5
CZ TO PDF
R/W R
x �
highest-order bit or vice versa.
from the high nibble into the low nibble in subtraction
not take place during a subtraction operation
3�
HT66F488/HT66F489
A/D Flash MCU with EEPROM
4 3 2
OV Z
R R/W R/W
� x x
�ove��e� ��� 2�1�
1 0
AC C
R/W R/W
x x
"x" unknown