C8051F52x-53x
SFR Definition 9.4. PSW: Program Status Word
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset Value
CY
AC
F0
RS1
RS0
OV
F1
PARITY 00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xD0
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to 0 by all other arithmetic operations.
AC: Auxiliary Carry Flag
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to 0 by all other arithmetic operations.
F0: User Flag 0.
Bit6:
Bit5:
This is a bit-addressable, general purpose flag for use under software control.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
RS1
RS0
Register Bank
Address
0x00–0x07
0x08–0x0F
0x10–0x17
0x18–0x1F
0
0
1
1
0
1
0
1
0
1
2
3
Bit2:
OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other
cases.
Bit1:
Bit0:
F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
PARITY: Parity Flag.
This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum
is even.
82
Rev. 0.3
SILICON [ SILICON ]
