AMD-K6 Datasheet, PDF (46/346 Pages) Advanced Micro Devices – AMD-K6 Processor

AMD-K6^® Processor Data Sheet
Preliminary Information
20695H/0—March 1998
Floating-Point
Register Data Types
Floating-point registers use four different types of data —
packed decimal, single precision real, double precision real,
and extended precision real. Figures 14 and 15 show the
formats for these registers.
79 78 72 71
Ignore
S _or
Zero
0
Precision — 18 Digits, 72 Bits Used, 4-Bits/Digit
Description
Bits
Ignored on Load, Zeros on Store 78-72
Sign Bit
79
Figure 14. Packed Decimal Data Type
Single Precision Real
Double Precision Real
63 62
52 51
S
Biased
Exponent
S = Sign Bit
Extended Precision Real
79 78
64 63 62
S
Biased
I
Exponent
S = Sign Bit
I = Integer Bit
Figure 15. Precision Real Data Types
31 30 23 22
0
S
Biased
Exponent
Significand
S = Sign Bit
0
Significand
0
Significand
28
Software Environment
Chapter 3