Real Number (Floating-Point Data) - Mitsubishi 00JCPU User Manual

2.4.4 Real number (Floating-point data)

There are two types of real number data: single-precision floating-point data and double-precision
floating-point data.
(1) Single-precision floating-point data
(a) Internal representation
Internal representation of real numbers used in the CPU module is given below.
Real number data can be represented as follows, using two word devices.
[Sign] 1. [Mantissa]
The bit configuration and the meaning of each bit are described below
b31 b30
b31
b30 to b23
Exponent (8 bits)
Sign
1) Sign
The most significant bit, b31, is the sign bit.
he most significant bit, b31, is the sign bit.
0: Positive
1: Negative
2) Exponent
The 8 bits, b23 to b30, represent the excess n of 2
The following shows the excess n according to the binary values in b23 to b30.
b23 to b30
n
Not used
3) Mantissa
Each of the 23 bits, b0 to b22, represents the "XXXXXX..." portion when the data is represented in binary,
"1.XXXXXX...".
[Exponent]
2
to b23 b22 to
Figure 2.47 Bit configuration of real number data
FF FE FD
H H
H
127 126
Figure 2.48 Relation between the exponent and excess n
b16 b15 to
b22 to b0
Mantissa (23 bits)
n
.
81 80 7F 7E
H H H H
2 1 0 -1
CHAPTER2 SEQUENCE PROGRAMS
b0
02 01 00
H H H
-125 -126 Not used
2 - 48
2
3