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Data Shift Instructions Section 3-8
Description ROL(027) shifts all bits of Wd including the Carry Flag (CY) to the left (from
rightmost bit to leftmost bit).
Flags
Precautions When ROL(027) is executed, the Error Flag will turn OFF.
If as a result of the shift the contents of Wd is zero, the Equals Flag will turn
ON.
If as a result of the shift the contents of the leftmost bit of Wd is 1, the Nega-
tive Flag will turn ON.
Note It is possible to set the Carry Flag contents to 1 or 0 immediately before exe-
cuting this instruction, by using the Set Carry (STC(040)) or Clear Carry
(CLC(041)) instructions.
Examples When CIO 0.00 is ON, word CIO 1000 and the Carry Flag (CY) will shift one
bit to the left. The contents of CIO 1000.15 will be shifted to the Carry Flag
(CY) and the Carry Flag contents will be shifted to CIO 1000.00.
3-8-10 DOUBLE ROTATE LEFT: ROLL(572)
Purpose Shifts all Wd and Wd +1 bits one bit to the left including the Carry Flag (CY).
Ladder Symbol
Name Label Operation
Error Flag ER OFF
Equals Flag = ON when the shift result is 0.
OFF in all other cases.
Carry Flag CY ON when 1 is shifted into the Carry Flag (CY).
OFF in all other cases.
Negative Flag N ON when the leftmost bit is 1 as a result of the shift.
OFF in all other cases.
CIO 1000
0.00
1000
Instruction executed once
Wd:
Wd
ROLL(572)
Wd: Word
Wd
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