NEC uPD75P3116 - Manual (Page 15)

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PD75P3116
15 Data Sheet U11369EJ3V0DS
4.2 Setting of Stack Bank Selection (SBS) Register
Use the stack bank selection register to switch between the Mk I mode and Mk II mode. Figure 4-1 shows the format
of the stack bank selection register.
The stack bank selection register is set using a 4-bit memory manipulation instruction. When using the Mk I mode, be
sure to initialize the stack bank selection register to 100
×B Note at the beginning of the program. When using the Mk II mode,
be sure to initialize it to 000 ×B Note .
Note Set the desired value for ×.
Figure 4-1. Format of Stack Bank Selection Register
Caution SBS3 is set to 1 after RESET input, and consequently the CPU operates in the Mk I mode. When using
instructions for the Mk II mode, set SBS3 to 0 and set the Mk II mode before using the instructions.
SBS3 SBS2 SBS1 SBS0 F84H
Address 3 2 1 0
SBS
0
0
1
1
0
1
0
1
Symbol
Stack area specification
Memory bank 0
Memory bank 1
Setting prohibited
0 Be sure to enter “0” for bit 2.
0
1
Mk II mode
Mk I mode
Mode selection specification