HD6473258CP10 Datasheet, PDF (37/301 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

3.2 Register Configuration
Figure 3-1 shows the register structure of the CPU. There are two groups of registers: the general
registers and control registers.
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07
R0H
R0L
R1H
R1L
R2H
R2L
R3H
R3L
R4H
R4L
R5H
R5L
R6H
R6L
R7H (SP) R7L
0
SP: Stack Pointer
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PC
0
PC: Program Counter
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CCR I U ^H U N ^{Z V C}
CCR: Condition Code Register
Carry flag
Overflow flag
Zero flag
Negative flag
Half-carry flag
Interrupt mask bit
User bit
User bit
Figure 3-1. CPU Registers
3.2.1 General Registers
All the general registers can be used as both data registers and address registers. When used as
address registers, the general registers are accessed as 16-bit registers (R0 to R7). When used as
data registers, they can be accessed as 16-bit registers, or the high and low bytes can be accessed
separately as 8-bit registers.
R7 also functions as the stack pointer, used implicitly by hardware in processing interrupts and
subroutine calls. In assembly-language coding, R7 can also be denoted by the letters SP. As
indicated in figure 3-2, R7 (SP) points to the top of the stack.
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