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Alpha 21264/EV67 Hardware Reference Manual
xix
Terminology and Conventions
This section defines the abbreviations, terminology, and other conventions used
throughout this document.
Abbreviations
•
Binary Multiples
The abbreviations K, M, and G (kilo, mega, and giga) represent binary multiples
and have the following values.
For example:
• Register Access
The abbreviations used to indicate the type of access to register fields and bits have
the following definitions:
K
=2
10
(1024)
M
=2
20
(1,048,576)
G
=2
30
(1,073,741,824)
2KB = 2 kilobytes
=2 × 2
10
bytes
4MB = 4 megabytes
=4 × 2
20
bytes
8GB = 8 gigabytes
=8 × 2
30
bytes
2K pixels = 2 kilopixels
=2 × 2
10
pixels
4M pixels = 4 megapixels
=4 × 2
20
pixels
Abbreviation Meaning
IGN Ignore
Bits and fields specified are ignored on writes.
MBZ Must Be Zero
Software must never place a nonzero value in bits and fields specified as
MBZ. A nonzero read produces an Illegal Operand exception. Also, MBZ
fields are reserved for future use.
RAZ Read As Zero
Bits and fields return a zero when read.
RC Read Clears
Bits and fields are cleared when read. Unless otherwise specified, such bits
cannot be written.
RES Reserved
Bits and fields are reserved by Compaq and should not be used; however,
zeros can be written to reserved fields that cannot be masked.
RO Read Only
The value may be read by software. It is written by hardware. Software write
operations are ignored.
RO,n Read Only, and takes the value n at power-on reset.
The value may be read by software. It is written by hardware. Software write
operations are ignored.