Maxim Integrated High-Speed Microcontroller - Manual (Page 49)

High-Speed Microcontroller User’s Guide
Rev: 062210 49 of 176
4.2.41 Program Status Word (PSW)
7 6 5 4 3 2 1 0
SFR D0h CY AC F0 RS1 RS0 OV F1 P
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 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.
AC
Bit 6 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.
F0
Bit 5 User Flag 0. This is a bit-addressable, general-purpose flag for software control.
RS1, RS0
Bits 4, 3 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
OV
Bit 2 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.
F1
Bit 1 User Flag 1. This is a bit-addressable, general-purpose flag for software control.
P
Bit 0 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.