h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 89

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

2.4.2
The CPU has eight 32-bit general registers. These general registers are all functionally alike and
can be used as both address registers and data 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 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 of 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 of sixteen 8-
bit registers.
Figure 2.8 illustrates the usage of the general registers. The usage of each register can be selected
independently.
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 2.9 shows the
stack.
• Address registers
• 32-bit registers
(ER0 to ER7)
ER registers
General Registers
Figure 2.8 Usage of General Registers
E registers (extended registers)
• 16-bit registers
R registers
(E0 to E7)
(R0 to R7)
Rev. 4.00 Jun 06, 2006 page 35 of 1004
• 8-bit registers
(R0H to R7H)
(R0L to R7L)
RH registers
RL registers
REJ09B0301-0400
Section 2 CPU