Page 54 - Engineering Digital Design

1.4 GLOSSARY OF TERMS, EXPRESSIONS, AND ABBREVIATIONS 25

Read/write memory (RWM): a memory array (e.g., RAM) that can be used to store and
retrieve information at any time.
Redundant cover: nonessential and nonoptional cover in a function representation.
Redundant prime implicant: a prime implicant that yields redundant cover.
Reflective code: a code that has a reflection (mirror) plane midway through the code.
Register: a digital device, configured with flip-flops and other logic, that is capable of
storing and shifting data on command.
Remainder: in division, the dividend minus the product of the divisor and the quotient.
Rendezvous module: an asynchronous state machine whose output becomes active when
all external inputs become active and becomes inactive when all external inputs become
inactive.
Reset: a logic 0 condition or an input to a logic device that sets it to a logic 0 condition.
Residue: the part of term that remains when the coupled variable is removed (see con-
sensus term).
Resistance, R: the voltage drop across a conducting element divided by current through
the element (in ohms).
Resistor-transistor logic: a logic family that consists of BJTs and resistors.
Restoring logic: logic consisting of switching devices such as BJTs and MOSFETs that
can amplify.
RET: rising edge triggered.
Reverse bias: a voltage applied to a p—n junction diode in a direction that minimizes
conduction across the junction.
Reverse saturation current: the current through a p-n junction diode under reverse bias.
Ring counter: a configuration of shift registers that generates a one-hot code output.
Ripple carry (R-C): the process by which a parallel adder transfers the carry from one
full adder to another.
Ripple counter: a counter whose flip-flops are each triggered by the output of the next
LSB flip-flop.
Rise time: he period of time it takes a voltage (or current) signal to change from 10% to
90% of its high value.
Rising edge triggered (RET): activation of a logic device on the rising edge of the
triggering variable.
RMOD: rendezvous module.
ROM: read-only memory.
Round-off error: the amount by which a magnitude is diminished due to an underflow
or spill-off in a shifter undergoing a right shift.
RPI: redundant prime implicant.
RTL: resistor-transistor logic.
Runt pulse: any pulse that barely reaches the switching threshold of a device into which
it is introduced.
S: set. Also, the source terminal of a MOSFET.
Sampling interval: sum of the setup and hold times.
Sampling variable: the last variable to change in initiating a state-to-state transition in
an FSM.
Sanity circuit: a circuit that is used to initialize an FSM into a particular state, usually a
resistor/capacitor (R-C) type circuit.