Register Bank Pointer (Rp); Figure 3.2-4 Structure Of Register Bank Pointer; Figure 3.2-5 Rule For Conversion Of Actual Addresses Of General-Purpose Register Area - Fujitsu F2MC-8L Series Hardware Manual

3.2.2

Register Bank Pointer (RP)

The register bank pointer (RP) located in the upper 8 bits of the program status (PS)
indicates the address of the general-purpose register bank currently in use. The RP is
converted to form the actual address in general-purpose register addressing.
Structure of Register Bank Pointer (RP)
Figure 3.2-4 shows the structure of the register bank pointer.
Bit 15 Bit 14 Bit 13 Bit 12 Bit 11Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
R4 R3
PS
X: Indeterminate
The register bank pointer indicates the address of the register bank currently in use. Figure 3.2-
5 shows the relationship between the register bank pointer contents and the actual address is
based on the conversion rule.

Figure 3.2-5 Rule for Conversion of Actual Addresses of General-purpose Register Area

Generated addresses
The register bank pointer points to the memory block (register bank) in the RAM area that is
used for general-purpose registers. A total of 32 register banks are available. A register bank is
specified by setting a value between "0" and "31" in the upper 5 bits of the register bank pointer.
Each register bank contains eight 8-bit general-purpose registers. Registers are specified by the
lower 3 bits of the operation codes.
Using the register bank pointer, the addresses "0100
as the general-purpose register area. However, the available area is limited on some products if
internal RAM only is used. The initial value after a reset is indeterminate.
Check:
• Before using any general-purpose register, be sure to set the register bank pointer (RP).
• The register bank pointer is part of the program status register (PS) and cannot be accessed
independently.

Figure 3.2-4 Structure of Register Bank Pointer

RP
R2 R1 R0 — —
"0" "0" "0" "0"
A15 A14 A13 A12 A10 A11 A9
CCR
— H I IL1 IL0
Upper bits of RP
"0" "0" "0" "1" R4
A8 A7
3.2 Dedicated Registers
RP initial value
N Z V C XXXXXXXX
Lower operation codes
R3 R2 R1 R0 b2
A6 A5 A4 A3 A2
" to a maximum of "01FF
H
B
b1 b0
A1 A0
" can be used
H
37