Intel 8XC251SQ User Manual
5-19
PROGRAMMING
.
Figure 5-3. Program Status Word 1 Register
PSW1
Address:
S:D1H
Reset State:
0000 0000B
7
0
CY
AC
N
RS1
RS0
OV
Z
—
Bit
Number
Bit
Mnemonic
Function
7
CY
Carry Flag:
Identical to the CY bit in the PSW register (Figure 5-2).
6
AC
Auxiliary Carry Flag:
Identical to the AC bit in the PSW register (Figure 5-2).
5
N
Negative Flag:
This bit is set if the result of the last logical or arithmetic operation was
negative (i.e., bit 15 = 1). Otherwise it is cleared.
negative (i.e., bit 15 = 1). Otherwise it is cleared.
4–3
RS1:0
Register Bank Select Bits 0 and 1:
Identical to the RS1:0 bits in the PSW register (Figure 5-2).
2
OV
Overflow Flag:
Identical to the OV bit in the PSW register (Figure 5-2).
1
Z
Zero Flag:
This flag is set if the result of the last logical or arithmetic operation is
zero. Otherwise it is cleared.
zero. Otherwise it is cleared.
0
—
Reserved:
The value read from this bit is indeterminate. Write a “0” to this bit.