123 / 132 page
HT80C51 User Manual
80C51 Family Instruction Set – Instruction definitions
Handshake Solutions
© Philips Electronics N.V. 2005
Page 123 of 132
RL A
Function: Rotate Accumulator Left
Description: The eight bits in the Accumulator are rotated one bit to the left. Bit 7 is rotated into the bit 0 posi-
tion. No flags are affected.
Example: The Accumulator holds the value 0C5H (11000101B). The instruction,
RL A
leaves the Accumulator holding the value 8BH (10001011B) with the carry unaffected.
Bytes: 1
Cycles: 1
Encoding:
Operation: RL
(An+1)
← (An), n = 0 – 6
(A0)
← (A7)
RLC A
Function: Rotate Accumulator Left through the Carry flag
Description: The eight bits in the Accumulator and the carry flag are together rotated one bit to the left. Bit 7
moves into the carry flag; the original state of the carry flag moves into the bit 0 position. No other
flags are affected.
Example: The Accumulator holds the value 0C5H (11000101B), and the carry is zero. The instruction,
RLC A
leaves the Accumulator holding the value 8AH (10001010B) with the carry set.
Bytes: 1
Cycles: 1
Encoding:
Operation: RLC
(An+1)
← (An), n = 0 – 6
(A0)
← (C)
(C)
← (A7)
0
0
1
0
0
0
1
1
0
0
1
1
0
0
1
1
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