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(2) Double-precision floating-point data
(a) Internal representation
Real number data used in the CPU module is internally represented as follows, using four word
devices.
[Sign] 1. [Mantissa]
The bit configuration and the meaning of each bit are described below
b63
b62
to
b63
b52 to b62
Exponent (11 bits)
Sign
1) Sign
The most significant bit, b63, is the sign bit
0: Positive
1: Negative
2) Exponent
The 11 bits, b52 to b62, represent the excess n of 2
The following shows the excess n according to the binary values in b52 to b62.
b52 to b62
7FE
7FF
H
n
Not used
1023
3) Mantissa
Each of the 52 bits, b0 to b51, represents the "XXXXXX..." portion when the data is represented in binary,
"1.XXXXXX...".
[Exponent]
2
b52
b51
b16
b15
to
Figure 2.40 Bit configuration of real number data
7FD
400
3FF
H
H
H
H
1022
2
1
Figure 2.41 Relation between the exponent and excess n
CHAPTER2 SEQUENCE PROGRAMS
to
b0 to b51
Mantissa (52 bits)
.
n
.
3FE
3FD
3FC
H
H
H
0
-1
-2
.
b0
02
01
00
H
H
H
-1021
-1022
Not used
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