Datasheet

Section 2 CPU
Rev. 6.00 Mar. 18, 2010 Page 72 of 982
REJ09B0054-0600
2.4.1 General Registers
The H8S/2000 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. Figure 2.7 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 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.
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 2.8 shows the
stack.
· 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 2.7 Usage of General Registers