S3F80JBCONTROL REGISTERS

FLAGS — System Flags Register

D5H Set1 Bank0

Bit Identifier

Reset Value

Read/Write

Addressing Mode

.7

.6

.5

.4

.3

.2

.1

.0

x

x

x

x

x

x

0

0

R/W

R/W

R/W

R/W

R/W

R/W

R

R/W

Register addressing mode only

.7

Carry Flag Bit (C)

 

 

 

 

0

Operation does not generate a carry or borrow condition

 

1

Operation generates a carry-out or borrow into high-order bit 7

.6

Zero Flag Bit (Z)

 

 

 

 

0

Operation result is a non-zero value

 

1

Operation result is zero

 

 

.5

Sign Flag Bit (S)

 

 

 

 

0

Operation generates a positive number (MSB = "0")

 

1

Operation generates a negative number (MSB = "1")

 

 

 

 

 

 

.4

Overflow Flag Bit (V)

 

 

 

 

0

Operation result is

+127

or

–128

 

1

Operation result is

> +127

or

< –128

.3

Decimal Adjust Flag Bit (D)

 

 

0Add operation completed

1Subtraction operation completed

.2

Half-Carry Flag Bit (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

 

 

 

.1

Fast Interrupt Status Flag Bit (FIS)

 

0

Interrupt return (IRET) in progress (when read)

 

1

Fast interrupt service routine in progress (when read)

.0

Bank Address Selection Flag Bit (BA)

 

0

Bank 0 is selected

 

1

Bank 1 is selected

4-11

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Samsung S3F80JB manual Flags System Flags Register D5H Set1 Bank0