z80189 ZiLOG Semiconductor, z80189 Datasheet - Page 193

• Manufacturer Part Number: z80189
• Description: Z80180, Z8s180, Z8l180 Mpu Operation
• Manufacturer: ZiLOG Semiconductor

178
Flag Register
UM005003-0703
Bit
Bit/Field
R/W
Reset
R = Read W = Write X = Indeterminate ? = Not Applicable
Bit
Position Bit/Field R/W
7
Z8018x
Family MPU User Manual
S
R/W
7
S
0
Stack Pointer (SP)
The Stack Pointer (SP) contains the memory address based LIFO stack.
SP is cleared to
Program Counter (PC)
The Program Counter (PC) contains the address of the instruction to be
executed and is automatically updated after each instruction fetch. PC is
cleared to
Flag Register (F)
The Flag Register stores the logical state reflecting the results of instruction
execution. The contents of the Flag Register are used to control program
flow and instruction operation.
R/W
R/W
Z
6
0
0000H
Value
0
Not Used
0000H
during reset.
5
?
?
Description
Sign
(bit 7) of the result. This is useful for operations with
signed numbers in which values with bit 7 = 1 are
interpreted as negative.
during reset.
.
S stores the state of the most significant bit
R/W
H
4
0
Not Used
3
?
?
R/W
P/V
2
0
R/W
N
1
0
R/W
C
0
0