Page 39 - Engineering Digital Design

10 CHAPTER 1 / INTRODUCTORY REMARKS AND GLOSSARY

Complementation: a condition that results from logic incompatibility; the mixed-logic
equivalent of the NOT operation.
Complex PLD: an on-chip array of PAL-like PLDs with I/O blocks and a programmable
interconnect structure.
Composite output map: a K-map that contains entries representing multiple outputs.
Computer: a digital device that can be programmed to perform a variety of tasks (e.g.,
computations) at extremely high speed.
Concatenation: act of linking together or being linked together in a series.
Conditional branching: state-to-state transitions that depend on the input status of the
FSM.
Conditional output: an output that depends on one or more external inputs.
Conjugate gate forms: a pair of logic circuit symbols that derive from the same physical
gate and that satisfy the DeMorgan relations.
Connective: a Boolean operator symbol (e.g., +, ®, n).
Consensus law: a law in Boolean algebra that allows simplification by removal of a
redundant term.
Consensus term: the redundant term that appears in a function obeying the consensus
law.
Controlled inverter: an XOR gate that is used in either the inverter or transfer mode.
Controller: that part of a digital system that controls the data path.
Conventional K-map: a K-map whose cell entries are exclusively 1's and O's.
Counter: a sequential logic circuit designed to count through a particular sequence of
states.
Counteracting delay: a delay placed on an external feedback path to eliminate an E-
hazard or d-trio.
Count sequence: a repeating sequence of binary numbers that appears on the outputs of
a counter.
Coupled term: one of two terms containing only one coupled variable.
Coupled variable: a variable that appears complemented in one term of an expression
(SOP or POS) and that also appears uncomplemented in another term of the same ex-
pression.
Cover: a set of terms that covers all minterms or maxterms of a function.
CPLD: complex PLD.
CPU: central processing unit.
Creeping code: any code whose bit positions fill with 1 's beginning at one end, and then
fill with O's beginning at the same end.
Critical race: a race condition in an asynchronous FSM that can result in transition to
and stable residence in an erroneous state.
CRMT: contracted Reed-Muller transformation.
Cross branching: multiple transition paths from one or more states in the state diagram
(or state table) of a sequential machine whereby unit distance coding of states is not
possible.
CU: control unit.
Current, /: the flow or transfer of charged matter (e.g., electrons) given in amperes (A).
Cutoff mode: the physical state of a BIT in which no significant collector current is
permitted to flow.
Cycle: two or more successive and uninterrupted state-to-state transitions in an asyn-
chronous sequential machine.