TS68882VR16 E2V, TS68882VR16 Datasheet - Page 25

• Manufacturer Part Number: TS68882VR16
• Manufacturer: E2V

Specifications of TS68882VR16

• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Compliant

8.7
8.8
e2v semiconductors SAS 2007
Packed Decimal String Real Data Format
Data Format Summary
The extended precision data format is also in conformance with the IEEE standard, but the standard
does not specify this format to the bit level as it does for single and double precision. The memory format
on the TS68882 consists of 96 bits (three long words). Only 80 bits are actually used, the other 16 bits
are for future expandability and for long-word alignment of floating-point data structures. Extended for-
mat has a 15-bit exponent, a 64-bit mantissa, and a 1-bit mantissa sign.
Extended precision numbers are intended for use as temporary variables, intermediate values, or in
places where extra precision is needed. For example, a compiler might select extended precision arith-
metic for evaluation of the right side of an equation with mixed sized data and then convert the answer to
the data type on the left side of the equation. It is anticipated that extended precision data will not be
stored in large arrays, due to the amount of memory required by each number.
The packed decimal string data format allows packed BCD strings to be input to and output from the
TS68882. The strings consist of a 3-digit base 10 exponent and a 17-digit base 10 mantissa. Both the
exponent and mantissa have a separate sign bit. All digits are packed BCD, such that an entire string fits
in 96 bits (three long words). As is the case with all data formats, when packed BCD strings are input to
the TS68882, the strings are automatically converted to extended precision real values. This allows
packed BCD numbers to be used as inputs to any operation. For example:
BCD numbers can be output from the TS68882 in a format readily used for printing by a program gener-
ated by a high-level language compiler. For example:
instructs the TS68882 to convert the floating-point data register 3 (FP3) contents into a packed BCD
string with five digits to the right of the decimal point (FORTRAN F format).
All data formats described above are supported orthogonally by all arithmetic and transcendental opera-
tions, and by all appropriate TS68000 Family addressing modes. For example, all of the following are
legal instructions:
On-chip calculations are performed to extended precision format, and the eight floating-point data regis-
ters always contain extended precision values. All data used in an operation is converted to extended
precision by the TS68882 before the specific operation is performed, and all results are in extended pre-
cision. This ensures accuracy without sacrificing performance.
Refer to
TS68882.
FADD.B
FADD.W
FADD.L
FADD.S
FADD.D
FADD.X
FADD.P
FADD.P # - 6.023E + 24, FP5
FMOVE.P FP3.BUFFER (# -5)
Figure 8-8
for a summary of the memory formats for the seven data formats supported by the
# 3.FP0
D2.FP3
BIGINT.FP7
# 3.14159.FP5
(SP) + .FP6
[(TEMP -PTR.A7)].FP3
# 1.23E25.FP0
0852B–HIREL–06/07
TS68882
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