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Special Math Instructions
Description
First word
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
1
0
1
0
0
0
0
exponent (0 to 7)
sign of exponent
Flags
Precautions
584
FDIV(079) 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.
Dr+1
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 leftmost digit can range from 0 to F; positive exponents
range from 0 to 7 and negative exponents range from 8 to F (0 to –7). The
rightmost 7 digits must be BCD.
1
0
0
0
1
0
0
0
mantissa (leftmost 3 digits)
0: +
1: –
Two more examples of floating-point values are:
6123 4567: 0.1234567
B123 4567: 0.1234567
The following table shows the maximum and minimum values allowed.
Limit
Maximum value
Minimum value
(Divisor and dividend)
Minimum value
(Result)
Name
Error Flag
Equals Flag
The result is expressed as a floating-point value, so it has 7 significant digits.
The eighth and higher digits are eliminated.
The result must be between 0.1000000
Dr
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
1
0
0
0
1
0
0
mantissa (rightmost 4 digits)
6
10
(6 = 0110 binary)
–3
10
(B = 1011 binary)
8-digit hexadecimal
7999 9999
F000 0001
F100 0000
Label
ER
ON if the mantissa (leftmost 7 digits) in Dd+1 and Dd is
not BCD.
ON if the mantissa (leftmost 7 digits) in Dr+1 and Dr is not
BCD.
ON if the divisor (Dr+1 and Dr) is 0.
ON if the result is not between 0.1000000
7
0.9999999
10
.
OFF in all other cases.
=
ON if the result is 0.
OFF in all other cases.
Section 3-14
Quotient
R+1
R
Dd+1
Dd
Second word
0
1
0
0
0
1
0
–2
=
0.1111113 x 10
Floating-point
0.9999999
10
0.0000001
10
0.1000000
10
Operation
10
–7
10
and 0.9999999
10
0
1
1
7
–7
–7
–7
and
7
.
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