MITSUBISHI MICROCOMPUTERS
4280 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS
FUNCTION BLOCK OPERATIONS
CPU
<Carry>
(CY)
(1) Arithmetic logic unit (ALU)
The arithmetic logic unit ALU performs 4-bit arithmetic such
as 4-bit data addition, comparison, and bit manipulation.
(M(DP))
Addition
ALU
(2) Register A and carry flag
(A)
Register A is a 4-bit register used for arithmetic, transfer,
exchange, and I/O operation.
<Result>
Carry flag CY is a 1-bit flag that is set to “1” when there is a
carry with the AMC instruction (Figure 1).
Fig. 1 AMC instruction execution example
It is unchanged with both A n instruction and AM instruction.
The value of A0 is stored in carry flag CY with the RAR
instruction (Figure 2).
<Set>
SC instruction
<Clear>
RC instruction
Carry flag CY can be set to “1” with the SC instruction and
cleared to “0” with the RC instruction.
CY
A3 A2 A1 A0
(3) Registers B and E
Register B is a 4-bit register used for temporary storage of 4-
bit data, and for 8-bit data transfer together with register A.
Register E is an 8-bit register. It can be used for 8-bit data
transfer with register B used as the high-order 4 bits and
register A as the low-order 4 bits (Figure 3).
<Rotation>
RAR instruction
A0
CY A3 A2 A1
Fig. 2 RAR instruction execution example
(4) Register D
Register D is a 3-bit register.
TAB instruction
Register B
It is used to store a 7-bit ROM address together with register
A and is used as a pointer within the specified page when the
TABP p, BLA p, or BMLA p instruction is executed (Figure 4).
Register A
B3
B2
B1
B0
A3 A2 A1 A0
TEAB instruction
Register E ER
7
ER6
ER5ER4ER3ER2ER1ER0
TABE instruction
B3 B2 B1 B0
A3 A2 A1 A0
Register B TBA instruction Register A
Fig. 3 Registers A, B and register E
ROM
4
TABP p instruction
Specifying address
8
0
Low-order 4 bits
Register A (4)
PCH
p3 p2 p1 p0
PCL
A3 A2 A1 A0
DR2 DR1DR0
Middle-order 4 bits
Register B (4)
Most significant 1 bit
The contents The contents
of register D of register A
Immediate field
value p
Carry flag CY (1)
URS flag (1)
URSC instruction
Fig. 4 TABP p instruction execution example
MITSUBISHI
ELECTRIC
6
MITSUBISHI [ Mitsubishi Group ]
