Z80180 Datasheet, PDF (193/326 Pages) Zilog, Inc. – Z8018x Family MPU

Z 8018x Fam ily
M PU Us e r M anual
178
Stack Pointer (SP)
The Stack Pointer (SP) contains the memory address based LIFO stack.
SP is cleared to 0000H during reset.
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 0000H during reset.
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.
Flag Register
Bit
7
6
5
4
3
2
1
0
Bit/Field
S
Z Not Used H Not Used P/V
N
C
R/W
R/W R/W
?
R/W
?
R/W R/W R/W
Reset
0
0
?
0
?
0
0
0
R = Read W = Write X = Indeterminate ? = Not Applicable
Bit
Position Bit/Field R/W
7
S
R/W
Value Description
0
Sign. S stores the state of the most significant bit
(bit 7) of the result. This is useful for operations with
signed numbers in which values with bit 7 = 1 are
interpreted as negative.
UM005001-ZMP0400