MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Glossary-4 Freescale Semiconductor
FFetch. Retrieving instructions from either the cache or main memory and placing them into
the instruction queue.
Fully-associative. Addressing scheme where every cache location (every byte) can have
any possible address.
GGeneral-purpose register (GPR). Any of the 32 registers in the general-purpose register
file. These registers provide the source operands and destination results for all
integer data manipulation instructions. Integer load instructions move data from
memory to GPRs and store instructions move data from GPRs to memory.
HHarvard architecture. An architectural model featuring separate caches for instruction
and data.
IIEEE 754. A standard written by the Institute of Electrical and Electronics Engineers that
defines operations and representations of binary floating-point arithmetic.
Illegal instructions. A class of instructions that are not implemented for a particular
processor that implement the PowerPC architecture. These include instructions
not defined by the PowerPC architecture. In addition, for 32-bit implementations,
instructions that are defined only for 64-bit implementations are considered to be
illegal instructions. For 64-bit implementations instructions that are defined only
for 32-bit implementations are considered to be illegal instructions.
Implementation. A particular processor that conforms to the PowerPC architecture, but
may differ from other architecture-compliant implementations for example in
design, feature set, and implementation of optional features. The PowerPC
architecture has many different implementations.
Implementation-dependent. An aspect of a feature in a processor’s design that is defined
by a processor’s design specifications rather than by the PowerPC architectur e.
Implementation-specific. An aspect of a feature in a processor’s design that is not required
by the PowerPC architecture, but for which the PowerPC architecture may provide
concessions to ensure that processors that implement the feature do so
consistently.
Imprecise exception. A type of synchronous exception that is allowed not to adhere to the
precise exception model (

see

Precise exception). The PowerPC architecture
allows only floating-point exceptions to be handled imprecisely.
Internal bus. The bus connecting the core and system interface unit (SIU).
Instruction latency. The total number of clock cycles necessary to execute a n instruction
and make ready the results of that instruction.