
22
MITSUBISHI MICROCOMPUTERS
4280 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS
SYMBOL
The symbols shown below are used in the following list of instruction function and the machine instructions.
Symbol
A
B
DR
ER
C
V1
PU0
LO
X
Y
DP
PC
PC
H
PC
L
SK
SP
CY
R1
T1
T1F
WDT
WDF1
WDF2
URS
P
STCK
INSTCK
Contents
Register A (4 bits)
Register B (4 bits)
Register D (3 bits)
Register E (8 bits)
Carrier wave selection register C (3 bits)
Timer control register V1 (3 bits)
Pull-down control register PU0 (3 bits)
Logic operation selection register LO (2 bits)
Register X (2 bits)
Register Y (4 bits)
Data pointer (6 bits)
(It consists of registers X and Y)
Program counter (10 bits)
High-order 3 bits of program counter
Low-order 7 bits of program counter
Stack register (10 bits
4)
Stack pointer (2 bits)
Carry flag
Timer 1 reload register
Timer 1
Timer 1 underflow flag
Watchdog timer
Watchdog timer flag 1
Watchdog timer flag 2
Most significant ROM code reference enable flag
Power down flag
System clock
Instruction clock
Contents
Port D (8 bits)
Port E (3 bits)
Port G (4 bits)
Port CARR (1 bit)
Hexadecimal variable
Hexadecimal variable
Hexadecimal variable
Hexadecimal constant which represents the
immediate value
Hexadecimal constant which represents the
immediate value
Binary notation of hexadecimal variable A
(same for others)
Direction of data movement
Data exchange between a register and memory
Decision of state shown before “”
Contents of registers and memories
Negate, Flag unchanged after executing
instruction
RAM address pointed by the data pointer
Label indicating address a
6
a
5
a
4
a
3
a
2
a
1
a
0
Label indicating address a
6
a
5
a
4
a
3
a
2
a
1
a
0
in page p
3
p
2
p
1
p
0
Hex. number C + Hex. number x (also same for
others)
Symbol
D
E
G
CARR
x
y
p
n
j
A
3
A
2
A
1
A
0
←
( )
—
M(DP)
a
p, a
C
+
x
Note : The 4280 Group just invalidates the next instruction when a skip is performed. The contents of program counter is not
increased by 2. Accordingly, the number of cycles does not change even if skip is not performed. However, the cycle count
becomes “1” if the TABP p, RT, or RTS instruction is skipped.