ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Glossary
Conditional execution
Means that if the condition code flags indicate that the corresponding condition is true when the instruction
starts executing, it executes normally. Otherwise, the instruction does nothing.
Configuration
Settings made on reset, or immediately after reset, and normally expected to remain static throughout
program execution.
Context switch
Is the saving and restoring of computational state when switching between different threads or processes. In
this manual, the term context switch is used to describe any situations where the context is switched by an
operating system and might or might not include changes to the address space.
Data cache
Is a separate cache used only for processing data loads and stores.
Digital signal processing (DSP)
Refers to a variety of algorithms that are used to process signals that have been sampled and converted to
digital form. Saturated arithmetic is often used in such algorithms.
Direct-mapped cache
Is a one-way set-associative cache. Each cache set consists of a single cache line, so cache look-up just needs
to select and check one cache line.
Direct Memory Access
Is an operation that accesses main memory directly, without the processor performing any accesses to the
data concerned.
DNM See Do-not-modify.
Domain Is a collection of sections, Large pages and Small pages of memory, that can have their access permissions
switched rapidly by writing to the Domain Access Control Register, in CP15 c3.
Do-not-modify (DNM)
Means the value must not be altered by software. DNM fields read as UNKNOWN values, and must only be
written with the same value read from the same field on the same processor.
Double-precision value
Consists of two 32-bit words that must appear consecutively in memory and must both be word-aligned, and
that is interpreted as a basic double-precision floating-point number according to the IEEE 754-1985
standard.
Doubleword
Is a 64-bit data item. Doublewords are normally at least word-aligned in ARM systems.
Doubleword-aligned
Means that the address is divisible by 8.
DSP See Digital signal processing
Endianness
Is an aspect of the system memory mapping. See big-endian and little-endian.
Glossary-4 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B