NEC PD754144 - Manual (Page 61)

CHAPTER 4 INTERNAL CPU FUNCTION
61 User’s Manual U10676EJ3V0UM
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.
Figure 4-1. Format of Stack Bank Select Register
3 2 Address 1 0
0 Memory bank 0
SBS SBS0 F84H SBS1 SBS3 SBS2
Symbol
Specifies stack area
0
Other than above, setting prohibited
0 Be sure to set bit 2 to 0.
0 Mkll mode
Selects mode
1 Mkl mode
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.