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ROLB
Operation:
Description:
Shifts all bits of accumulator B one place to the left. Bit 0 is loaded from
the C status bit. The C bit is loaded from the most significant bit of B. Ro-
tate operations include the carry bit to allow extension of shift and rotate
operations to multiple bytes. For example, to shift a 24-bit value one bit
to the left, the sequence ASL LOW, ROL MID, ROL HIGH could be used
where LOW, MID and HIGH refer to the low-order, middle and high-order
bytes of the 24-bit value, respectively.
Condition Codes and Boolean Formulas:
S
–
N:
Z:
V:
C:
Addressing Modes, Machine Code, and Execution Times:
Source Form
ROLB
MOTOROLA
6-172
Rotate Left B
C
X
H
I
N
Z
∆
∆
–
–
–
Set if MSB of result is set; cleared otherwise.
Set if result is $00; cleared otherwise.
N ⊕ C = [N • C] + [N • C] (for N and C after the shift)
Set if (N is set and C is cleared) or (N is cleared and C is set); cleared oth-
erwise (for values of N and C after the shift).
B7
Set if the MSB of B was set before the shift; cleared otherwise.
Address Mode
INH
INSTRUCTION GLOSSARY
b7
b0
– – – – – –
V
C
∆
∆
Object Code
55
ROLB
Cycles
Access Detail
1
O
CPU12
REFERENCE MANUAL
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