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Program status word register (PSW)
NAME
ADDRESS
PSW
0D0H
BIT LOCATION
FLAG
PSW.0
P
PSW.1
F1
PSW.2
OV
PSW.3
RS0
PSW.4
RS1
PSW.5
F0
PSW.6
AC
PSW.7
CY
MSB
7
6
5
CY
AC
F0
Accumulator (ACC) parity indicator.
This bit is "1" when the "1" bit number in the accumulator is an odd number, and
"0" when an even number.
User flag which may be set to "0" or "1" as desired by the user.
Overflow flag which is set if the carry C6 from bit 6 of the ALU or CY is "1" as a
result of an arithmetic operation. The flag is also set to "1" if the resultant product
of executing multiplication instruction (MUL AB) is greater than 0FFH, but is reset
to "0" if the product is less than or equal to 0FFH.
RAM register bank switch
RS1
RS0
BANK
0
0
0
0
1
1
1
0
2
1
1
3
User flag which may be set to "0" or "1" as desired by the user.
Auxiliary carry flag.
This flag is set to "1" if a carry C
executing an arithmetic operation instruction.
In all other cases, the flag is reset to "0".
Main carry flag.
This flag is set to "1" if a carry C
executing an arithmetic operation instruction.
If a carry C
is not generated, the flag is reset to "0".
7
MSM80C154S/83C154S
4
3
2
RS1
RS0
OV
FUNCTION
RAM ADDRESS
00H - 07H
08H - 0FH
10H - 17H
18H - 1FH
is generated from bit 3 of the ALU as a result of
3
is generated from bit 7 of the ALU as result of
7
LSB
1
0
F1
P
275
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