LITE5200B User’s Manual, Rev. 2
Freescale Semiconductor
Glossary-11
Supervisor mode.
The privileged operation state of a processor. In supervisor mode,
software, typically the operating system, can access all control registers and can
access the supervisor memory space, among other privileged operations.
Synchronization.
A process to ensure that operations occur strictly
in order
. See
Context
synchronization
and
Execution synchronization
.
Synchronous exception.
An
exception
that is generated by the execution of a particular
instruction or instruction sequence. There are two types of synchronous
exceptions,
precise
and
imprecise
.
System memory.
The physical memory available to a processor.
T
Tenure.
The period of bus mastership. For the 603e, there can be separate address bus
tenures and data bus tenures. A tenure consists of three phases: arbitration,
transfer, and termination.
TLB (translation lookaside buffer).
A cache that holds recently-used
page table entries
.
Throughput.
The measure of the number of instructions that are processed per clock
cycle.
Transaction.
A complete exchange between two bus devices. A transaction is typically
comprised of an address tenure and one or more data tenures, which may overlap
or occur separately from the address tenure. A transaction may be minimally
comprised of an address tenure only.
Transfer termination.
Signal that refers to both signals that acknowledge the transfer of
individual beats (of both single-beat transfer and individual beats of a burst
transfer) and to signals that mark the end of the tenure.
U
UISA (user instruction set architecture).
The level of the architecture to which
user-level software should conform. The UISA defines the base user-level
instruction set, user-level registers, data types, floating-point memory conventions
and exception model as seen by user programs, and the memory and programming
models.
Underflow.
A condition that occurs during arithmetic operations when the result cannot
be represented accurately in the destination register. For example, underflow can
happen if two floating-point fractions are multiplied and the result requires a
smaller
exponent
and/or
mantissa
than the single-precision format can provide. In
other words, the result is too small to be represented accurately.
User mode.
The operating state of a processor used typically by application software. In
user mode, software can access only certain control registers and can access only
user memory space. No privileged operations can be performed. Also referred to
as problem state.