UPD784044 Datasheet, PDF (22/90 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784044(A), 784046(A)
6.2.2 Control registers
(1) Program counter (PC)
This is a 20-bit program counter. Its contents are automatically updated as the program is executed.
Figure 6-4. Program Counter (PC) Format
19
0
PC
(2) Program status word (PSW)
This register retains the status of the CPU and its contents are automatically updated as the program is
executed.
Figure 6-5. Program Status Word (PSW) Format
15
14
13
12
11
10
PSWH
UF
RBS2 RBS1 RBS0
—
—
PSW
7
PSWL
S
6
5
4
3
2
Z
RSS^Note AC
IE
P/V
9
8
—
—
1
0
0
CY
Note This flag is provided so that the µPD784046(A) maintains compatibility with the 78K/III series. Be sure
to clear this flag to 0 when using 78K/III series software.
(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 high-order 4 bits of this pointer.
Figure 6-6. Stack Pointer (SP) Format
23
20
0
SP
0000
22