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CHAPTER 3 CPU ARCHITECTURE
User’s Manual U19780EJ2V0UD
60
Figure 3-9. Data to Be Restored from Stack Memory
(a) POP rp instruction (when SP = FEDEH)
Register pair lower
FEE0H
SP
SP
FEE0H
FEDFH
FEDEH
Register pair higher
FEDEH
(b) RET instruction (when SP = FEDEH)
PC15 to PC8
FEE0H
SP
SP
FEE0H
FEDFH
FEDEH
PC7 to PC0
FEDEH
(c) RETI, RETB instructions (when SP = FEDDH)
PC15 to PC8
PSW
FEDFH
FEE0H
SP
SP
FEE0H
FEDEH
FEDDH
PC7 to PC0
FEDDH
3.2.2 General-purpose registers
General-purpose registers are mapped at particular addresses (FEE0H to FEFFH) of the data memory. The
general-purpose registers consists 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 also be used in a pair as a 16-bit register
(AX, BC, DE, and HL).
These registers 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 by 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.