Fujitsu MB90460 Series, Hardware Manual, Page: 69 / 739

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CHAPTER 3 CPU
3.7.5 Register Bank Pointer (PS: RP)
The register bank pointer (RP) is a register that indicates the first address of the
general-purpose register bank currently being used. The RP is used for real address
conversion when general-purpose register addressing is used.
■
Register Bank Pointer (RP)
Figure 3.7-10 shows the configuration of the register bank pointer (RP) register.
Figure 3.7-10 Configuration of the Register Bank Pointer (RP)
■
General-purpose Register Area and Register Bank Pointer
The register bank pointer points to the relationship between the general-purpose register of the F
2
MC-
16LX and the address in internal RAM where the general-purpose register exists. Figure 3.7-11 shows the
conversion rules used for the relationship between the contents of the RP and the real address.
Figure 3.7-11 Conversion Rules for Physical Address of General-purpose Register Area
• Since the RP takes a value from 00
H
to 1F
H
, the first address of the register bank can be set in the range
from 000180
H
to 00037F
H
.
• Although an assembler instruction can use an 8-bit immediate value transfer instruction for transfer to
the RP, in actuality only the lower 5 bits of the data are used.
• The initial value of the RP register after a reset is 00
H
.
B4 B3 B2 B1 B0 : RP
0 0 0 0 0 Default value
⇒
bit 8 9 10 11 12
000180
H
000370
H
Conversion formula [000180
H
+ (RP)
×
10
H
]
Register bank 31
Register bank 16
Register bank 0
000280
H
When RP = 10
H