Mitsubishi microcomputers
M16C / 61 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
CPU
Central Processing Unit (CPU)
The CPU has a total of 13 registers shown in Figure 1.5.1. Seven of these registers (R0, R1, R2, R3, A0,
A1, and FB) come in two sets; therefore, these have two register banks.
b15
b15
b15
b15
b15
b15
b15
b8 b7
b8 b7
b0
b0
b0
b0
b0
b0
b0
R0(Note)
R1(Note)
R2(Note)
R3(Note)
A0(Note)
A1(Note)
FB(Note)
L
L
H
H
b19
b19
b0
PC
Program counter
Data
registers
b0
b0
Interrupt table
register
INTB
H
L
b15
b15
b15
b15
User stack pointer
USP
ISP
SB
b0
b0
b0
Interrupt stack
pointer
Address
registers
Static base
register
FLG
Frame base
registers
Flag register
IPL
U
I O B S Z D C
Note: These registers consist of two register banks.
Figure 1.5.1. Central processing unit register
(1) Data registers (R0, R0H, R0L, R1, R1H, R1L, R2, and R3)
Data registers (R0, R1, R2, and R3) are configured with 16 bits, and are used primarily for transfer and
arithmetic/logic operations.
Registers R0 and R1 each can be used as separate 8-bit data registers, high-order bits as (R0H/R1H),
and low-order bits as (R0L/R1L). In some instructions, registers R2 and R0, as well as R3 and R1 can
use as 32-bit data registers (R2R0/R3R1).
(2) Address registers (A0 and A1)
Address registers (A0 and A1) are configured with 16 bits, and have functions equivalent to those of data
registers. These registers can also be used for address register indirect addressing and address register
relative addressing.
In some instructions, registers A1 and A0 can be combined for use as a 32-bit address register (A1A0).
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MITSUBISHI [ Mitsubishi Group ]
