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5-17-13 FLOATING POINT DIVIDE – FDIV(79)
Dd
: First dividend word (BCD)
IR, SR, AR, DM, HR, TC, LR
Dr
: First divisor word (BCD)
IR, SR, AR, DM, HR, TC, LR
Ladder Symbols
Operand Data Areas
R
: First result word
IR, AR, DM, HR LR
FDIV(79)
Dd
Dr
R
@FDIV(79)
Dd
Dr
R
Dr and Dr+1 cannot contain zero. Dr and Dr+1 must be in the same data
area, as must Dd and Dd+1; R and R+1.
When the execution condition is OFF, FDIV(79) is not executed. When the
execution condition is ON, FDIV(79) divides the floating-point value in Dd and
Dd+1 by that in Dr and Dr+1 and places the result in R and R+1.
R+1
R
Quotient
Dd+1
Dd
Dr+1
Dr
To represent the floating point values, the rightmost seven digits are used for
the mantissa and the leftmost digit is used for the exponent, as shown in the
diagram below. The mantissa is expressed as a value less than one, i.e., to
seven decimal places.
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
First word
Exponent (0 to 7)
Sign of exponent
0: +
1: –
1
0
1
0
0
0
0
1
0
0
0
1
0
0
0
1
Mantissa (leftmost 3 digits)
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Second word
Mantissa (rightmost 4 digits)
0
0
0
1
0
0
0
1
0
0
0
1
0
0
1
1
= 0.1111113 x 10
–2
ER:
Dr and Dr+1 contain 0.
Dd, Dd+1, Dr, or Dr+1 is not BCD.
The result is not between 0.0000001 x 10
–7
and 0.999999 x 10
+7
.
Indirectly addressed DM word is non-existent. (Content of
*
DM word
is not BCD, or the DM area boundary has been exceeded.)
EQ
:
ON when the result is 0.
Limitations
Description
Flags
BCD Calculations
Section 5-17