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EMULS
(D) × (Y) ⇒ Y : D
Operation:
Description:
A signed 16-bit value is multiplied by a signed 16-bit value to produce a
signed 32-bit result. The first source operand must be loaded into 16-bit
double accumulator D and the second source operand must be loaded
into index register Y before executing the instruction. When the instruc-
tion is executed, D is multiplied by the value Y. The 16 high-order bits of
the 32-bit result are stored in Y and the 16 low-order bits of the result are
stored in D.
The C status bit can be used to round the high-order 16 bits of the result.
Condition Codes and Boolean Formulas:
N:
Z:
C:
Addressing Modes, Machine Code, and Execution Times:
Source Form
EMULS
MOTOROLA
6-86
Extended Multiply
16-Bit by 16-Bit (Signed)
S
X
H
I
N
∆
–
–
–
–
Set if the MSB of the result is set; cleared otherwise.
Set if result is $00000000; cleared otherwise.
Set if bit 15 of the result is set; cleared otherwise.
Address Mode
INH
INSTRUCTION GLOSSARY
Z
V
C
∆
∆
–
Object Code
18 13
EMULS
Cycles
Access Detail
3
OfO
CPU12
REFERENCE MANUAL
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