MOTOROLA
Glossary of Terms and Abbreviations
Glossary-1
Glossary of Terms and Abbreviations
The glossary contains an alphabetical list of terms, phrases, and abbreviations used in this
book. Some of the terms and definitions included in the glossary are reprinted from
IEEE
Std 754-1985, IEEE Standard for Binary Floating-Point Arithmetic
, copyright 1985 by
the Institute of Electrical and Electronics Engineers, Inc. with the permission of the IEEE.
Note that some terms are defined in the context of how they are used in this book.
Architecture.
A detailed specification of requirements for a processor or
computer system. It does not specify details of how the processor or
computer system must be implemented; instead it provides a
template for a family of compatible
implementations
.
Atomic.
A bus access that attempts to be part of a read-write operation to the
same address uninterrupted by any other access to that address (the
term refers to the fact that the transactions are indivisible). The 60x
processor initiates the read and write separately, but signals the
memory system that it is attempting an atomic operation. If the
operation fails, status is kept so that the 60x can try again. The 60x
implements atomic accesses through the
lwarx
/
stwcx.
instruction
pair, which asserts the TT0 signal.
Beat
. A single state on the 60x interface that may extend across multiple bus
cycles. A 60x transaction can be composed of multiple address or
data beats.
Big-endian
. A byte-ordering method in memory where the address n of a
word corresponds to the
most-significant byte
. In an addressed
memory word, the bytes are ordered (left to right) 0, 1, 2, 3, with 0
being the most-significant byte.
See
Little-endian.
Block
. An area of memory that ranges from 128 Kbyte to 256 Mbyte, whose
size, translation, and protection attributes are controlled by the block
address translation (BAT) mechanism
.
Buffer
. A temporary storage mechanism for queuing data.
A
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