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RORA
Operation:
Description:
Shifts all bits of accumulator A one place to the right. Bit 7 is loaded from
the C status bit. The C bit is loaded from the least significant bit of A. 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 right, the sequence LSR HIGH, ROR MID, ROR LOW 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
RORA
MOTOROLA
6-174
Rotate Right A
b7
– – – – – –
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).
A0
Set if the LSB of A was set before the shift; cleared otherwise.
Address Mode
INH
INSTRUCTION GLOSSARY
C
b0
V
C
∆
∆
Object Code
46
RORA
Cycles
Access Detail
1
O
CPU12
REFERENCE MANUAL
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