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 Contents Symbol Contents
Register A (4 bits)
Register B (4 bits)
Register D (3 bits)
Register E (8 bits)
Port D (8 bits)
Port E (3 bits)
Port G (4 bits)
Port CARR (1 bit)
A
D
E
G
B
DR
ER
C
CARR
Carrier wave selection register C (3 bits)
Timer control register V1 (3 bits)
Hexadecimal variable
V1
x
y
p
n
PU0
LO
Pull-down control register PU0 (3 bits)
Logic operation selection register LO (2 bits)
Hexadecimal variable
Hexadecimal variable
Hexadecimal constant which represents the
immediate value
X
Register X (2 bits)
Register Y (4 bits)
Hexadecimal constant which represents the
immediate value
Y
j
DP
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
Binary notation of hexadecimal variable A
(same for others)
A3A2A1A0
PC
PCH
PCL
SK
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
SP
( )
—
CY
R1
Timer 1 reload register
Timer 1
T1
Timer 1 underflow flag
Watchdog timer
M(DP)
a
RAM address pointed by the data pointer
Label indicating address a6 a5 a4 a3 a2 a1 a0
Label indicating address a6 a5 a4 a3 a2 a1 a0
in page p3 p2 p1 p0
T1F
WDT
WDF1
WDF2
URS
P
Watchdog timer flag 1
Watchdog timer flag 2
Most significant ROM code reference enable flag
Power down flag
p, a
Hex. number C + Hex. number x (also same for
others)
C
+
x
STCK
INSTCK
System clock
Instruction clock
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.
MITSUBISHI
ELECTRIC
22
MITSUBISHI [ Mitsubishi Group ]
