C8051F93X Datasheet, PDF (111/330 Pages) Silicon Laboratories – Pipelined intstruction architecture executes 70 of instruction in 1 or 2 system clocks

C8051F93x-C8051F92x
SFR Definition 8.6. PSW: Program Status Word
Bit
7
6
5
4
3
2
1
0
Name
CY
AC
F0
RS[1:0]
OV
F1
PARITY
Type R/W
R/W
R/W
R/W
R/W
R/W
R
Reset
0
0
0
0
0
0
0
0
SFR Page = All Pages; SFR Address = 0xD0; Bit-Addressable
Bit Name
Function
7
CY Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a bor-
row (subtraction). It is cleared to logic 0 by all other arithmetic operations.
6
AC Auxiliary Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a
borrow from (subtraction) the high order nibble. It is cleared to logic 0 by all other arith-
metic operations.
5
F0 User Flag 0.
This is a bit-addressable, general purpose flag for use under software control.
4:3 RS[1:0] Register Bank Select.
These bits select which register bank is used during register accesses.
00: Bank 0, Addresses 0x00-0x07
01: Bank 1, Addresses 0x08-0x0F
10: Bank 2, Addresses 0x10-0x17
11: Bank 3, Addresses 0x18-0x1F
2
OV Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all
other cases.
1
F1 User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
0 PARITY Parity Flag.
This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared
if the sum is even.
Rev. 1.3
111