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CHAPTER 2 CPU
■ General-purpose registers
The F
2
MC-16LX general-purpose registers are located from addresses 000180
H
to 00037F
H
(maximum
configuration) of main storage. The register bank pointer (RP) indicates which of the above addresses are
currently being used as a register bank. Each bank has the following three types of registers. These registers
are mutually dependent as described in Figure 2.7-2 .
• R0 to R7: 8-bit general-purpose register
• RW0 to RW7: 16-bit general-purpose register
• RL0 to RL3: 32-bit general-purpose register
Figure 2.7-2 General-purpose Registers
The relationship between the high-order and low-order bytes of a byte or word register is expressed as
follows:
RW
(i+4)
= R
(i × 2+1)
× 256+R
(i × 2)
[i=0 to 3]
The relationship between the high-order and low-order bytes of RLi and RW can be expressed as follows:
RL
(i)
= RW
(i × 2+1)
× 65536+RW
(i × 2)
[i=0 to 3]
000180H RP x 10H
MSB LSB
RW0
RW1
RW2
RW3
R1
R3
R5
R7
R2
R4
R6
RW4
RW5
RW6
RW7
RL0
RL1
RL2
RL3
16 bits
R0
Start address of
general-purpose register
Low-order
High-order