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A quadword is specified by its address A, the address of the byte containing bit 0. A quadword is a
Note:
Alpha implementations will impose a significant performance penalty when accessing quadword operands that are not naturally aligned. (A naturally aligned quadword has zero as the
2.2.5 VAX Floating-Point Formats
VAX
2.2.5.1 F_floating
An F_floating datum is 4 contiguous bytes in memory starting on an arbitrary byte boundary. The bits are labeled from right to left, 0 through 31, as shown in Figure
Figure 2–5: F_floating Datum
31 | 16 15 14 | 7 | 6 | 0 |
Fraction Lo
S
Exp.
Frac. Hi :A
An F_floating operand occupies 64 bits in a floating register,
Figure 2–6: F_floating Register Format
63 62 | 52 51 | 29 28 | 0 |
S
Exp.
Fraction
0
:Fx
The F_floating load instruction reorders bits on the way in from memory, expands the expo- nent from 8 to 11 bits, and sets the
Basic Architecture