Table 2-6 Typical Function Of The General-Purpose Register - Fujitsu MB90420/5 (A) Series Hardware Manual

n Register bank
The register bank can be used as a general-purpose register (byte registers R0 to R7, word registers RW0 to
RW7, and long word registers RL0 to RL3) to perform various operations or to serve as a pointer. The long
word register can also be used as a linear pointer to directly access the entire memory space. Same as with
ordinary RAM, the data in the register bank is not initialized by a reset, meaning that the state before the
reset is held. However, at power-on, the value is undefined. Table 2-6 shows the typical function of the
general-purpose register.

Table 2-6 Typical Function of the General-Purpose Register

Register Name
R0 to R7 Used as operands for various instructions
Note: R0 can also be used as the barrel shift instruction counter or the normalize
RW0 to RW7 Used as pointers
Used as operands for various instructions
Note: RW0 can also be used as the string instruction counter.
RL0 to RL3 Used as long pointers
Used as operands for various instructions
(normalization) instruction counter.
CPU
Function
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