H8SLASH3003 datasheet(40/715 Pages) RENESAS

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2.4.2 General Registers

The H8/300H CPU has eight 32-bit general registers. These general registers are all functionally

alike and can be used without distinction between data registers and address registers. When a

general register is used as a data register, it can be accessed as a 32-bit, 16-bit, or 8-bit register.

When the general registers are used as 32-bit registers or as address registers, they are designated

by the letters ER (ER0 to ER7).

The ER registers divide into 16-bit general registers designated by the letters E (E0 to E7) and R

(R0 to R7). These registers are functionally equivalent, providing a maximum sixteen 16-bit

registers. The E registers (E0 to E7) are also referred to as extended registers.

The R registers divide into 8-bit general registers designated by the letters RH (R0H to R7H) and

RL (R0L to R7L). These registers are functionally equivalent, providing a maximum sixteen 8-bit

registers.

Figure 2-4 illustrates the usage of the general registers. The usage of each register can be selected

independently.

Figure 2-4 Usage of General Registers

• Address registers

• 32-bit registers

• 16-bit registers

• 8-bit registers

ER registers

ER0 to ER7

E registers

(extended registers)

E0 to E7

R registers

R0 to R7

RH registers

R0H to R7H

RL registers

R0L to R7L

H8/3003 Datasheet(PDF) 40 Page - Renesas Technology Corp