z8f0822 ZiLOG Semiconductor, z8f0822 Datasheet - Page 240

• Manufacturer Part Number: z8f0822
• Description: High Performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

Flags Register
PS022517-0508
Bit
The Flags Register contains the status information regarding the most recent arithmetic,
logical, bit manipulation or rotate and shift operation. The Flags Register contains six bits
of status information that are set or cleared by CPU operations. Four of the bits (C, V, Z
and S) can be tested with conditional jump instructions. Two flags (H and D) cannot be
tested and are used for Binary-Coded Decimal (BCD) arithmetic.
The two remaining bits, User Flags (F1 and F2), are available as general-purpose status
bits. User Flags are unaffected by arithmetic operations and must be set or cleared by
instructions. The User Flags cannot be used with conditional Jumps. They are undefined at
initial power-up and are unaffected by Reset.
positions in the Flags Register.
Interrupts, the Software Trap (TRAP) instruction, and Illegal Instruction Traps all write
the value of the Flags Register to the stack. Executing an Interrupt Return (IRET) instruc-
tion restores the value saved on the stack into the Flags Register.
C
7
Z
S
V
D
H F2 F1
Bit
Figure 56. Flags Register
0
Flags Register
User Flags
Half Carry Flag
Decimal Adjust Flag
Overflow Flag
Sign Flag
Zero Flag
Carry Flag
Figure 56
Z8 Encore! XP
illustrates the flags and their bit
Product Specification
eZ8 CPU Instruction Set
®
F0822 Series
227