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S3C80A5B
FLAGS
— System Flags Register
Bit Identifier
RESET Value
Read/Write
Addressing Mode
.7
.6
.5
.4
.3
.2
.1
.0
.7
.6
x
x
R/W
R/W
Register addressing mode only
Carry Flag (C)
0
Operation does not generate a carry or borrow condition
1
Operation generates a carry-out or borrow into high-order bit 7
Zero Flag (Z)
0
Operation result is a non-zero value
1
Operation result is zero
Sign Flag (S)
0
Operation generates a positive number (MSB = "0")
1
Operation generates a negative number (MSB = "1")
Overflow Flag (V)
Operation result is ≤ +127 or –128
0
1
Operation result is > +127 or < –128
Decimal Adjust Flag (D)
0
Add operation completed
1
Subtraction operation completed
Half-Carry Flag (H)
0
No carry-out of bit 3 or no borrow into bit 3 by addition or subtraction
1
Addition generated carry-out of bit 3 or subtraction generated borrow into bit 3
Fast Interrupt Status Flag (FIS)
0
Interrupt return (IRET) in progress (when read)
1
Fast interrupt service routine in progress (when read)
Bank Address Selection Flag (BA)
0
Bank 0 is selected
(normal setting for S3C80A5B)
1
Invalid selection (bank 1 is not implemented)
.5
.4
x
x
R/W
R/W
R/W
CONTROL REGISTERS
D5H
.3
.2
.1
x
x
0
R/W
R
Set 1
.0
0
R/W
4-9
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