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Glossary-6
MPC7400 RISC Microprocessor Users Manual
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.
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 oating-point exceptions to be
handled imprecisely.
Instruction queue
. A holding place for instructions fetched from the current
instruction stream.
Integer unit
. A functional unit in the MPC750 responsible for executing
integer instructions.
In-order.
An aspect of an operation that adheres to a sequential model. An
operation is said to be performed in-order if, at the time that it is
performed, it is known to be required by the sequential execution
model.
See
Out-of-order.
Instruction latency
. The total number of clock cycles necessary to execute
an instruction and make ready the results of that instruction.
Interrupt
. An
asynchronous exception
. On PowerPC processors, interrupts
are a special case of exceptions. See also asynchronous exception.
Key bits
. A set of key bits referred to as Ks and Kp in each segment register
and each BAT register. The key bits determine whether supervisor or
user programs can access a
page
within that
segment
or
block
.
Kill
. An operation that causes a
cache block
to be invalidated without writing
any modiTed data to memory.
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Latency.
The number of clock cycles necessary to execute an instruction and
make ready the results of that execution for a subsequent instruction.
L2 cache
.
See
Secondary cache.
Least-signiTcant bit (lsb)
. The bit of least value in an address, register, data
element, or instruction encoding.
Least-signiTcant byte (LSB)
. The byte of least value in an address, register,
data element, or instruction encoding.
K
L