Intel 8253 - Table 3-6 Intel387 SX Math Coprocessor Data Type Representation in Memory

Intel387
TM
SX MATH COPROCESSOR
Table 3-6. Intel387
TM
SX Math CoProcessor Data Type Representation in Memory
240225–23
NOTES:
1. S
e
Sign bit (0
e
positive, 1
e
negative)
2. d
n
e
Decimal digit (two per byte)
3. X
e
Bits have no significance; Math CoProcessor ignores when loading, zeros when storing
4.
U
e
Position of implicit binary point
5. I
e
Integer bit of significand; stored in temporary real, implicit in single and double precision
6. Exponent Bias (normalized values):
Single: 127 (7FH)
Double: 1023 (3FFH)
Extended REal: 16383 (3FFFH)
7. Packed BCD: (
b
1)
S
(D
17
..D
0
)
8. Real: (
b
1)
S
(2
E-BIAS
)(F
0
F
1
...)
19
19