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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.
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.
0 — Reserved:
The value read from this bit is indeterminate. Write a “0” to this bit.