Zilog ZUSBOPTS User Manual
Page 492
Glossary
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Zilog Developer Studio II – ZNEO™
User Manual
NEG.
Negate.
NMI.
Nonmaskable interrupt.
NOP.
An acronym for No Operation, an instruction whose sole function is to increment the program coun-
ter, but that does not affect any changes to registers or memory.
O
Op Code.
Operation Code, a quantity that is altered by a microprocessor’s instruction. Also abbreviated
OPC.
OR.
Bitwise OR.
OV.
Overflow.
P
PC.
Program counter.
pipeline.
The act of initiating a bus cycle while another bus cycle is in progress. Thus, the bus can have
multiple bus cycles pending at a time.
POP.
Retrieve a value from the stack.
port.
The point at which a communications circuit terminates at a network, serial, or parallel interface
card.
power.
The rate of transfer or absorption of energy per unit time in a system.
push.
To store a value in the stack.
R
RAM.
Random-access memory. A memory that can be written to or read at random. The device is usually
volatile, which means the data is lost without power.
random-access memory (RAM).
A read/write, nonsequential-access memory used for the storage of
instructions and data.
read-only memory (ROM).
A type of memory in which data, under normal conditions, can only be read.
Nonvolatile computer memory that contains instructions that do not require change, such as permanent
parts of an operating system. A computer can read instructions from ROM, but cannot store new data in
ROM. Also called nonerasable storage.
register.
A device, accessible to one or more input circuits, that accepts and stores data. A register is most
often used only as a device for temporary storage of data.
ROM.
See read-only memory.
RR.
Rotate Right.