DS80C390_00 Datasheet, PDF (68/155 Pages) Dallas Semiconductor – High-Speed Microcontroller User’s Guide Supplement

DS80C390 High-Speed Microcontroller User’s Guide Supplement
Program Status Word (PSW)
7
6
5
4
3
2
1
0
SFR D0h CY
AC
F0
RS1
RS0
0V
F1 PARITY
RW-0 RW-0 RW-0 RW-0 RW-0 RW-0 RW-0 RW-0
R=Unrestricted Read, W=Unrestricted Write, -n=Value after Reset
CY
Bit 7
AC
Bit 6
F0
Bit 5
RS1, RS0
Bits 4-3
OV
Bit 2
F1
Bit 1
PARITY
Bit 0
Carry Flag. This bit is set when if the last arithmetic operation resulted in a carry
(during addition) or a borrow (during subtraction). Otherwise it is cleared to 0 by
all arithmetic operations.
Auxiliary Carry Flag. This bit is set to 1 if the last arithmetic operation resulted
in a carry into (during addition), or a borrow (during subtraction) from the high
order nibble. Otherwise it is cleared to 0 by all arithmetic operations.
User Flag 0. This is a bit-addressable, general-purpose flag for software control.
Register Bank Select 1–0. These bits select which register bank is addressed
during register accesses.
RS1
RS0
REGISTER BANK
ADDRESS
0
0
0
00h – 07h
0
1
1
08h – 0Fh
1
0
2
10h – 17h
1
1
3
18h – 1Fh
Overflow Flag. This bit is set to 1 if the last arithmetic operation resulted in a
carry (addition), borrow (subtraction), or overflow (multiply or divide).
Otherwise it is cleared to 0 by all arithmetic operations.
User Flag 1. This is a bit-addressable, general-purpose flag for software control.
Parity Flag. This bit is set to 1 if the modulo-2 sum of the eight bits of the
accumulator is 1 (odd parity); and cleared to 0 on even parity.
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