Page 40 - Engineering Digital Design

1.4 GLOSSARY OF TERMS, EXPRESSIONS, AND ABBREVIATIONS 11

Data bus: a parallel set of conductors which are capable of transmitting or receiving data
between two parts of a system.
Data lockout: the property of a flip-flop that permits the data inputs to change immediately
following a reset or set operation without affecting the flip-flop output.
Data lockout flip-flop: a one-bit memory device which has the combined properties of a
master/slave flip-flop and an edge triggered flip-flop.
Data path: the part of a digital system that is controlled by the controller.
Data path unit: the group of logic devices that comprise the data path.
Data selector: a multiplexer.
Data-triggered: referring to flip-flops triggered by external inputs (no clock) as in the
pulse mode.
DCL: digital combination lock.
Deactivate: to make inactive.
Deassert: deactivate.
Debounce: to remove the noise that is produced by a mechanical switch.
Debouncing circuit: a circuit that is used to debounce a switch.
Decade: a quantity of 10.
Decoder: a combinational logic device that will activate a particular minterm code output
line determined by the binary code input. A demultiplexer.
Decrement: reduction of a value by some amount (usually by 1).
Delay: the time elapsing between related events in process.
Delay circuit: a circuit whose purpose it is to delay a signal for a specified period of
time.
Delimiter: a character used to separate lexical elements and has a specific meaning in a
given language. Examples are @, #, +, /,', >.
DeMorgan relations: mixed logic expressions of DeMorgan's laws.
DeMorgan's laws: a property that states that the complement of the Boolean product of
terms is equal to the Boolean sum of their complements; or that states that the complement
of the Boolean sum of terms is the Boolean product of their complements.
Demultiplexer: a combinational logic device in which a single input is selectively steered
to one of a number of output lines. A decoder.
Depletion mode: a normally ON NMOS that has a conducting n-type drain-to-source
channel in the absence of a gate voltage but that looses its conducting state when the
gate voltage reaches some negative value.
D flip-flop: a one-bit memory device whose output value is set to the D input value on
the triggering edge of the clock signal.
D-flop module: a memory element that is used in an EAIC system and that has charac-
teristics similar to that of a D flip-flop.
Diagonal pattern: an XOR pattern formed by identical EV subfunctions in any two
diagonally located cells of a K-map whose coordinates differ by two bits.
Difference: the result of a subtraction operation.
Digit: a single symbol in a number system.
Digital: related to discrete quantities.
Digital combination lock: a sequence recognizer that can be used to unlock or lock
something.
Digital engineering design: the design and analysis of digital devices.
Digital signal: a logic waveform composed of discrete logic levels (e.g., a binary digital
signal).