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3.2.2 General-purpose registers
General-purpose registers are mapped at particular addresses (FEE0H to FEFFH) of the data memory. They
consist of 4 banks, each bank consisting of eight 8-bit registers (X, A, C, B, E, D, L, and H).
Each register can be used as an 8-bit register, and two 8-bit registers can be used in pairs as a 16-bit register
(AX, BC, DE, and HL).
They can be described in terms of function names (X, A, C, B, E, D, L, H, AX, BC, DE, and HL) and absolute
names (R0 to R7 and RP0 to RP3).
Register banks to be used for instruction execution are set using the CPU control instruction (SEL RBn). Because
of the 4-register bank configuration, an efficient program can be created by switching between a register for normal
processing and a register for interrupts for each bank.
FEFFH
BANK0
FEF8H
BANK1
FEF0H
BANK2
FEE8H
BANK3
FEE0H
FEFFH
BANK0
FEF8H
BANK1
FEF0H
BANK2
FEE8H
BANK3
FEE0H
CHAPTER 3 CPU ARCHITECTURE
Figure 3-16. General-Purpose Register Configuration
(a) Absolute name
16-bit processing
15
(b) Function name
16-bit processing
15
User's Manual U11302EJ4V0UM
RP3
RP2
RP1
RP0
0
HL
DE
BC
AX
0
8-bit processing
R7
R6
R5
R4
R3
R2
R1
R0
7
0
8-bit processing
H
L
D
E
B
C
A
X
7
0
63
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