INSTRUCTION DESCRIPTIONS
A - 80 INSTRUCTION SET DETAILS MOTOROLA
Operation: Assembler Syntax:
D–1 ➞ D DEC D
Description: Decrement by one the specified operand and store the result in the destina-
tion accumulator. One is subtracted from the LSB of D.
Example:
:
DEC A ;Decrement the content of A accumulator by one
:
Explanation of Example: One is subtracted from the content of the A accumulator.
Condition Codes:
L — Set if overflow has occurred in result. Not affected otherwise
E — Set if the signed integer portion of result is in use
U— Set if result is unnormalized
N — Set if bit 55 of result is set
Z — Set if result equals zero
V — Set if overflow has occurred in result
C — Set if a borrow occurs from bit 55 of result
DEC Decrement by One DEC
MR CCR
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
LF DM T ** S1 S0 I1 I0 S LEUNZVC