HD64F36074G datasheet(45/564 Pages) RENESAS

45 / 564 page

Section 2 CPU

Rev. 3.00 Sep. 10, 2007 Page 13 of 528

REJ09B0216-0300

2.2.1

General Registers

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

identical and can be used as both address registers and data registers. The general registers are

available for use as 32-, 16-, and 8-bit data registers. Figure 2.3 illustrates the usage of the general

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

designated by the letters ER (ER0 to ER7).

The ER registers are divided 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 of sixteen 16-

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

The R registers are divided into 8-bit registers designated by the letters RH (R0H to R7H) and RL

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

registers.

The usage of each register can be selected independently.

• 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)

Figure 2.3 Usage of General Registers

General register ER7 has the function of stack pointer (SP) in addition to its general-register

function, and is used implicitly in exception handling and subroutine calls. Figure 2.4 shows the

relationship between the stack pointer and the stack area.

HD64F36074G Datasheet(PDF) 45 Page - Renesas Technology Corp