NXP Semiconductors Lite5200B, Руководство пользователя, Страница: 130 / 138

LITE5200B User’s Manual, Rev. 2
Glossary-12 Freescale Semiconductor
V
VEA (virtual environment architecture). The level of the architecture that describes the
memory model for an environment in which multiple devices can access memory,
defines aspects of the cache model, defines cache control instructions, and defines
the time-base facility from a user-level perspective. Implementations that conform
to the PowerPC VEA also adhere to the UISA, but may not necessarily adhere to
the OEA.
Virtual address. An intermediate address used in the translation of an effective address to
a physical address.
Virtual memory. The address space created using the memory management facilities of
the processor. Program access to virtual memory is possible only when it coincides
with physical memory .
W
Way. A location in the cache that holds a cache block, its tags and status bits.
Word. A 32-bit data element.
Write-back. A cache memory update policy in which processor write cycles are directly
written only to the cache. External memory is updated only indirectly, for
example, when a modified cache block is cast out to make room for newer data.
Write-through. A cache memory update policy in which all processor write cycles are
written to both the cache and memory.