CONTROL REGISTERSS3C84E5/C84E9/P84E9

FLAGS — System Flags Register

D5H

Set 1

Bit Identifier

Reset Value

Read/Write Addressing Mode

.7

.6

.5

.4

.3

.2

.1

.0

.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

Carry Flag (C)

0Operation does not generate a carry or underflow condition

1Operation generates a carry-out or underflow into high-order bit 7

Zero Flag (Z)

0Operation result is a non-zero value

1Operation result is zero

Sign Flag (S)

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

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

Overflow Flag (V)

0

Operation result is

£ +127

or

³

–128

 

 

 

 

 

 

1

Operation result is

> +127

or

<

–128

 

 

 

 

 

 

Decimal Adjust Flag (D)

0Add operation completed

1Subtraction operation completed

Half-Carry Flag (H)

0No carry-out of bit 3 or no underflow into bit 3 by addition or subtraction

1Addition generated carry-out of bit 3 or subtraction generated underflow into bit 3

Fast Interrupt Status Flag (FIS)

0Interrupt return (IRET) in progress (when read)

1Fast interrupt service routine in progress (when read)

Bank Address Selection Flag (BA)

0Bank 0 is selected

1Bank 1 is selected

4-8

Page 77
Image 77
Samsung S3C84E5 user manual Flags System Flags Register, D5H