µPD784214A, 784215A, 784216A, 784217A, 784218A, 784214AY, 784215AY, 784216AY, 784217AY, 784218AY
6.2.2 Control registers
(1) Program counter (PC)
The program counter is a 20-bit register whose contents are automatically updated when the program is
executed.
Figure 6-7. Format of Program Counter (PC)
19
0
PC
(2) Program status word (PSW)
This register holds the statuses of the CPU. Its contents are automatically updated when the program is
executed.
Figure 6-8. Format of Program Status Word (PSW)
15
14
13
12
11
10
9
8
PSWH
UF RBS2 RBS1 RBS0
–
–
–
–
PSW
7
PSWL
S
6
5
4
3
2
1
0
Z
RSSNote AC
IE
P/V
0
CY
Note This flag is provided to maintain compatibility with the 78K/III Series. Be sure to clear this flag to 0,
except when the software for the 78K/III Series is used.
(3) Stack pointer (SP)
This is a 24-bit pointer that holds the first address of the stack. Be sure to write 0 to the higher 4 bits of this
pointer.
Figure 6-9. Format of Stack Pointer (SP)
23
20
0
SP
0000
30
Data Sheet U14121EJ2V0DS00