Register Bank Pointer (Ps: Rp); Fig. 2.21 Configuration Of Register Bank Pointer (Rp); Fig. 2.22 Physical Address Conversion Rules In General-Purpose Register Area - Fujitsu MB90420/5 (A) Series Hardware Manual

2.7.5 Register Bank Pointer (PS: RP)

The register bank pointer (RP) indicates the starting address of the currently used general-purpose register
bank, and is used for the real address conversion at general-purpose register addressing.
n Register bank pointer (RP)
Figure 2.21 shows the configuration of the register bank pointer (RP) register.
ILM
bit 15 bit 14 bit 13 bit 12 bit 11 bit 10
ILM2 ILM1 ILM0 B4
PS
n General-purpose register area and register bank pointer
The register bank pointer indicates the relationships between general-purpose registers of the F
and the addresses of the internal RAM where those registers exist. The relationships between the RP data
and the real addresses are shown as the conversion rules in Figure 2.22.
Conversion expression [000180
When RP = 10

Fig. 2.22 Physical Address Conversion Rules in General-purpose Register Area

• RP has value ranging from 00
in the range of 000180
• The assembler instruction can use the 8-bit immediate value transfer instruction that is transferred to RP,
but only the lower 5 bits of that data is actually used.
• The initial value of the RP register is set to 00
RP
bit 9 bit 8
B3 B2 B1 B0

Fig. 2.21 Configuration of Register Bank Pointer (RP)

+ (RP) × 10
H
H
to 1F . Consequently, the starting address of the register bank can be set
H H
to 00037F .
H H
H
CPU
bit 7 bit 6 bit 5 bit 4
— I S T
]
H
000370
000280
000180
after a reset.
2-23
CCR
bit 43 bit 2 bit 1 bit 0
N Z V
Register bank 31
H
•
•
•
H
Register bank 16
•
•
•
H
Register bank 0
Initial value
of RP
00000
C
B
2
MC-16LX