Texas Instruments MSC1210 User Manual
Page 293
8052 Instruction Set
E-9
8052 Instruction Set
DEC
Decrement Register
Syntax
DEC register
Instructions
OpCode
Bytes
Cycles
Flags
DEC A
0x14
1
1
None
DEC direct
0x15
2
1
None
DEC @R0
0x16
1
1
None
DEC @R1
0x17
1
1
None
DEC R0
0x18
1
1
None
DEC R1
0x19
1
1
None
DEC R2
0x1A
1
1
None
DEC R3
0x1B
1
1
None
DEC R4
0x1C
1
1
None
DEC R5
0x1D
1
1
None
DEC R6
0x1E
1
1
None
DEC R7
0x1F
1
1
None
DEC decrements the value of register by 1. If the initial value of register is 0,
decrementing the value causes it to reset to 255 (0xFF
H
).
Note:
The carry flag is not set when the value rolls over from 0 to 255.
See also: INC, SUBB
DIV
Divide Accumulator by B
Syntax
DIV AB
Instructions
OpCode
Bytes
Cycles
Flags
DIV AB
0x84
1
1
C, OV
Divides the unsigned value of the accumulator by the unsigned value of the
B register. The resulting quotient is placed in the accumulator and the
remainder is placed in the B register.
The carry (C) flag is always cleared.
The overflow (OV) flag is set if division by 0 was attempted. Otherwise, it is
cleared.
See also: MUL AB