354
Symbol Math Instructions Section 3-10
Description –L(411) subtracts the binary values in Su and Su+1 from Mi and Mi+1 and
outputs the result to R, R+1. When the result is negative, it is output to R and
R+1 as a 2’s complement.
Flags
Precautions When –L(411) is executed, the Error Flag will turn OFF.
If as a result of the subtraction, the content of R, R+1 is 00000000 hex, the
Equals Flag will turn ON.
If the subtraction results in a borrow, the Carry Flag will turn ON.
If the result of subtracting a negative number from a positive number is nega-
tive (in the range 80000000 to FFFFFFFF hex), the Overflow Flag will turn
ON.
If the result of subtracting a positive number from a negative number is posi-
tive (in the range 00000000 to 7FFFFFFF hex), the Underflow Flag will turn
ON.
If as a result of the subtraction, the content of the leftmost bit of R+1 is 1, the
Negative Flag will turn ON.
Examples When CIO 0.01 is ON in the following example, D1201 and D1200 will be sub-
tracted from D1001 and D1000 as 8-digit signed binary values and the result
will be output to D1501 and D1500.
Su+1
CY R
Mi+1
R+1
Mi
Su
(Signed binary)
(Signed binary)
(Signed binary)
CY will turn
ON when there
is a borrow.
−
Name Label Operation
Error Flag ER OFF
Equals Flag = ON when the result is 0.
OFF in all other cases.
Carry Flag CY ON when the subtraction results in a borrow.
OFF in all other cases.
Overflow Flag OF ON when the result of subtracting a negative number
from a positive number is in the range 80000000 to
FFFFFFFF hex.
OFF in all other cases.
Underflow Flag UF ON when the result of subtracting a positive number from
a negative number is in the range 00000000 to
7FFFFFFF hex.
OFF in all other cases.
Negative Flag N ON when the leftmost bit of the result is 1.
OFF in all other cases.
−L
0.01
D1000
D1200
D1500
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