UPD784218 Datasheet, PDF (25/92 Pages) NEC – 16-/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784218, 784218Y
7.2.2 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 7-3. Program Counter (PC) Format
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.
PSWH
Figure 7-4. Program Status Word (PSW) Format
15
14
13
12
11
10
9
8
UF RBS2 RBS1 RBS0
–
–
–
–
PSW
7
PSWL
S
6
5
4
3
2
1
0
Z
RSS^Note 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 7-5. Stack Pointer (SP) Format
23
20
0
SP
0000
Data Sheet U12304EJ2V0DS00
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