Page 45 - Engineering Digital Design

16 CHAPTER 1 / INTRODUCTORY REMARKS AND GLOSSARY

Go/No-Go configuration: a single input controlling the hold and exit conditions of a
state in a state diagram.
Gray code: a reflective unit distance code.
Ground: a reference voltage level usually taken to be zero volts.
GS: group signal.
Half adder (HA): a combinational logic device that adds two binary bits and issues a
sum bit and a carry-out bit.
Half subtracter: a combinational logic device that subtracts one binary bit from another
and issues a difference bit and a borrow-out bit.
Hamming distance: as used in this text, the number of state variables required to change
during a given state-to-state transition in an FSM.
Handshake interface: a configuration between two devices whereby the outputs of one
device are the inputs to the other and vice versa.
Hang state: an isolated state in which an FSM can reside stably but which is not part of
the authorized routine.
Hardware description language (HDL): a high-level programming language with spe-
cialized structures for modeling hardware.
Hazard: a glitch or unauthorized transition that is caused by an asymmetric path delay
via an inverter, gate, or lead during a logic operation.
Hazard cover: the redundant cover that removes a static hazard.
HDL: hardware description language.
Heuristic: by empirical means or by discovery.
Hexadecimal (hex): a base 16 number system in which alphanumeric symbols are
used to represent 4-bit binary numbers 0000 through 1111. (See Binary coded
hexadecimal.)
Hold condition: branching from a given state back into itself or the input requirements
necessary to effect such branching action.
Holding register: a PIPO (storage) register that is used to filter output signals.
Hold time: the interval of time immediately following the transition point during which
the data inputs must remain logically stable to ensure that the intended transition of the
FSM will be successfully completed.
Hole: the absence of a valence electron — the majority carrier in a p-type conducting
semiconductor.
HV: high voltage.
Hybrid function: any function containing both SOP and POS terms.
1C: integrated circuit.
ICS: iterated carry-save.
Implicant: a term in a reduced or minimized expression.
Inactive: not active and implying logic 0.
Inactive state: the logic 0 state of a logic device.
Inactive transition point: the point in a voltage waveform where a digital device passes
from the active state to the inactive state.
Incompatibility: a condition where the input to a logic device and the input requirement
of that device are of opposite activation levels.
Incompletely specified function: a function that contains nonessential minterms or max-
terms (see Don't care).
Increment: to increase usually by 1.