Bank Select Prefix (Pcb, Dtb, Adb, And Spb); Table 2-7 Bank Select Prefix; Table 2-8 Instructions Unaffected By Bank Select Prefix - Fujitsu MB90420/5 (A) Series Hardware Manual

2.9.1 Bank Select Prefix (PCB, DTB, ADB, and SPB)

When an instruction is prefixed by the bank select prefix, the memory space accessed by the instruction can
be selected arbitrarily irrespective of the addressing type.
n Bank select prefix (PCB, DTB, ADB, SPB)
The memory space used when accessing data is defined for each addressing type. However, when an
instruction is prefixed by the bank select prefix, the memory space accessed by the instruction can be
selected arbitrarily irrespective of the addressing type.
Table 2-7 shows the bank select prefix and the selected memory space.
Bank Select Prefix
PCB
DTB
ADB
SPB
When the bank select prefix is used, some instructions perform an exceptional operation. Table 2-8 shows
the instructions not affected by the bank select prefix, and Table 2-9 shows the instructions requiring care
when using the bank select prefix.
Instruction Type
String MOVS
instructiondd
SCEQ
FILS
Stack operation PUSHW
instruction
I/O Access MOV
instruction
MOVW
MOV
MOV
MOVB
SETB
BBC
WBTC
Interrupt return RETI
instruction

Table 2-7 Bank Select Prefix

Program space
Data space
Additional space
When the value of the S flag of the condition code register (CCR) is 0,
the user stack space is used. When it is 1, the system stack space is
used.

Table 2-8 Instructions Unaffected by Bank Select Prefix

Instruction
MOVSW
SCWEQ
FILSW
POPW
A, io MOVW
A, io
io, A MOVW
io, #imm8 MOVW
A, io: bp MOVB
io: bp CLRB
io: bp, rel BBS
io, bp WBTS
CPU
Selected Space
The bank register specified for the operand
is used irrespective of the prefix.
Irrespective of the prefix, the user stack
bank (USB) is used when the S flag is 0;
and the system stack bank (SSB) is used
when the S flag is 1.
A, io The I/O space (000000
accessed irrespective of the prefix.
io, A
io, #imm16
io: bp, A
io: bp
io: bp, rel
io: bp
The system stack bank (SSB) is used
irrespective of the prefix.
2-31
Results
to 0000FF ) is
H H