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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
RAM Data Memory
Program Status Word
This register contains the Parity flag (P), General purpose flag 1 (F1), overflow flag (OV), Register
bank select control bits (RS0, RS1), General purpose flag 0 (F0), Auxiliary Carry flag (AC) and
Carry flag (CY). These arithmetic/logical operation and system management flags are used to
record the status and operation of the microcontroller. Note that the Parity bit can only be modified
by hardware depending upon the ACC state.
PSW Register – Program Status Word Register
SFR Address: D0h
Bit
7
6
5
4
3
2
1
0
Name
CY
AC
F0
RS1
RS0
OV
F1
P
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
POR
0
0
0
0
0
0
0
0
Bit 7
CY:
Carry flag
0: No carry-out
1: An operation results in a carry during arithmetic operations and accumulator for
Boolean operations.
Bit 6
AC:
Auxiliary flag
0: No auxiliary carry
1: An operation results in a carry out of the low nibbles in addition, or no borrow
from the high nibble into the low nibble on subtraction.
Bit 5
F0:
General Purpose Flag 0
This bit is used as a general purpose flag by the application program.
Bit 4~3
RS1~RS0:
Select Data Memory Banks
00: Bank 0
01: Bank 1
10: Bank 2
11: Bank 3
RS1
RS0
Selected Register Bank
Locations (within Internal Data Area)
0
0
Bank 0
00H – 07H
0
1
Bank 1
08H – 0FH
1
0
Bank �
10H – 17H
1
1
Bank 3
18H – 1FH
Bit 2
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
highest-order bit or vice versa.
Bit 1
F1:
General Purpose Flag 1
This bit is used as a general purpose flag by the application program.
Bit 0
P:
Parity flag
0: Accumulator contains an even number of ‘1’s
1: Accumulator contains an odd number of ‘1’s
This bit is used to indicate the number of ‘1’s in the Accumulator.