Setting Stack Bank Select Register (Sbs); Format Of Stack Bank Select Register - NEC PD754144 User Manual

4.1.2 Setting stack bank select register (SBS)

The MkI mode or MkII mode is selected by using the stack bank select register (SBS). Figure 4-1 shows the format
of this register.
The stack bank select register is set by using a 4-bit memory manipulation instruction. To use the MkI mode, be
sure to initialize the stack bank select register to 1000B at the beginning of the program. To use the MkII mode, initialize
the register to 0000B.
Address
F84H
Caution The SBS.3 bit is set to "1" after the RESET signal has been asserted. Therefore, the CPU operates
in the MkI mode. To use the instructions in the MkII mode, clear SBS.3 to "0" to set the MkII mode.
CHAPTER 4 INTERNAL CPU FUNCTION
Figure 4-1. Format of Stack Bank Select Register
3 2 1 0
SBS3 SBS2 SBS1 SBS0
User's Manual U10676EJ3V0UM
Symbol
SBS
Specifies stack area
0 0 Memory bank 0
Other than above, setting prohibited
0 Be sure to set bit 2 to 0.
Selects mode
0 Mkll mode
1 Mkl mode
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