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8052 Instruction Set
E-23
8052 Instruction Set
SJMP Short Jump
Syntax SJMP relAddr
Instructions OpCode Bytes Cycles Flags
SJMP relAddr 0x80 2 2 None
SJMP jumps unconditionally to the address specified relAddr. RelAddr must
be within −128 or +127 bytes of the instruction that follows the SJMP instruc-
tion.
See also: LJMP, AJMP
SUBB Subtract from Accumulator with Borrow
Syntax SUBB A,operand
Instructions OpCode Bytes Cycles Flags
SUBB A,#data8 0x94 2 1 C, AC, OV
SUBB A,direct 0x95 2 1 C, AC, OV
SUBB A,@R0 0x96 1 1 C, AC, OV
SUBB A,@R1 0x97 1 1 C, AC, OV
SUBB A,R0 0x98 1 1 C, AC, OV
SUBB A,R1 0x99 1 1 C, AC, OV
SUBB A,R2 0x9A 1 1 C, AC, OV
SUBB A,R3 0x9B 1 1 C, AC, OV
SUBB A,R4 0x9C 1 1 C, AC, OV
SUBB A,R5 0x9D 1 1 C, AC, OV
SUBB A,R6 0x9E 1 1 C, AC, OV
SUBB A,R7 0x9F 1 1 C, AC, OV
SUBB subtracts the value of operand from the value of the accumulator, leav-
ing the resulting value in the accumulator. The value operand is not affected.
The carry (C) bit is set if a borrow was required for bit 7. Otherwise, it is cleared.
In other words, if the unsigned value being subtracted is greater than the accu-
mulator, the carry flag is set.
The auxillary carry (AC) bit is set if a borrow was required for bit 3. Otherwise,
it is cleared. In other words, the bit is set if the low nibble of the value being
subtracted was greater than the low nibble of the accumulator.
The overflow (OV) bit is set if a borrow was required for bit 6 or for bit 7, but
not both. In other words, the subtraction of two signed bytes resulted in a value
outside the range of a signed byte (−128 to 127). Otherwise, it is cleared.
See also: ADD, ADDC, DEC