HD6433640 HITACHI [Hitachi Semiconductor], HD6433640 Datasheet - Page 27

• Manufacturer Part Number: HD6433640
• Description: H8/3644 Series Hardware Manual
• Manufacturer: HITACHI [Hitachi Semiconductor]

2.2
2.2.1
All the general registers can be used as both data registers and address registers.
When used as data registers, they can be accessed as 16-bit registers (R0 to R7), or the high bytes
(R0H to R7H) and low bytes (R0L to R7L) can be accessed separately as 8-bit registers.
When used as address registers, the general registers are accessed as 16-bit registers (R0 to R7).
R7 also functions as the stack pointer (SP), used implicitly by hardware in exception processing
and subroutine calls. When it functions as the stack pointer, as indicated in figure 2.2, SP (R7)
points to the top of the stack.
2.2.2
The CPU control registers include a 16-bit program counter (PC) and an 8-bit condition code
register (CCR).
Program Counter (PC): This 16-bit register indicates the address of the next instruction the CPU
will execute. All instructions are fetched 16 bits (1 word) at a time, so the least significant bit of
the PC is ignored (always regarded as 0).
SP (R7)
Register Descriptions
General Registers
Control Registers
Figure 2.2 Stack Pointer
Lower address side [H'0000]
Upper address side [H'FFFF]
Unused area
Stack area
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