Maxim Integrated Secure Microcontroller - Manual (Page 45)

Secure Microcontroller User’s Guide
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Program Status Word Register
PSW, 0D0H
D7 D6 D5 D4 D3 D2 D1 D0
C AC F0 RS1 RS0 OV P
RW-0 RW-0 RW-0 RW-0 RW-0 RW-0 R-0
R = Unrestricted Read Access, W = Unrestricted Write Access, T = Timed-access Write Only, n = Value after Reset, * = Special: see description
PSW.7 C
Carry Set when the previous operation resulted in a carry (during addition) or a borrow
(during subtraction). Otherwise cleared.
PSW.6
AC
Auxiliary-Carry Set when the previous operation resulted in a carry (during addition) or a borrow
(during subtraction) from the low-order nibble. Otherwise cleared.
PSW.5
F0
User Flag 0 General-purpose flag bit that can be set or cleared as needed.
PSW.4-3
R1–R0
Register Bank Select Used to select an 8-byte bank of registers within the data register space to be
assigned as R0–R8 in subsequent instructions. The 8-byte bank starting address
selection is as follows:
R1 R0 DATA REGISTER ADDRESS (R0)
0 0 00h
0 1 08h
1 0 10h
1 1 18h
PSW.2
OV
Overflow Set when a carry was generated into the high-order bit, but not a carry out of the
high-order bit as a result of the previous operation, and vice versa. OV is normally
used in 2’s complement arithmetic.
PSW.0
P
Parity Set if the modulo-2 sum of the eight bits of the accumulator is 1 (odd parity);
cleared on even parity.