DIGELEC1 (Finals) Flashcards
An example of a basic flip-flop is the
RS flip flop
RS flip flop is formed by
two cross-coupled NOR and NAND gate
How many outputs and inputs does an RS flip flop have
INPUT
- Reset
- Set
OUTPUT
- Q
- Not Q
In RS flip flop the outputs are always
opposite
In RS flip flop what input is described as “illegal” or “unallowed”
R = 1
S = 1
a device that serves as a temporary buffer memory. It is used to hold data after the input signal is removed.
Latch
Example of a latch device
D flip flop
The data are latched when the enable line is
Low
the output follows the input when the enable line is
High
It occurs when the output follows/is the same as the input only when the enable is active
Transparent latch
2 categories of binary counters
- Synchronous
- Asynchronous
The input clock pulse is first felt by the first flip-flop. The effect is not felt by the second flip-flop immediately because of the delay through the first flip-flop.
Asynchronous
Asynchronous counters are commonly referred to as
Ripple counter
a counter in which each stage is
clocked at the same time
Synchronous
Synchronous counter is also called
Parallel counter
have a modulus of ten, or ten states in their counting sequence. A common type of this counter is the BCD (8421) counter, which produces a binary-coded-decimal sequence
Decade counter
A counter than can
count in either direction through
a certain sequence.
up-down counter
up-down counter is also called
bidirectional counter
are constructed of flip-flops wired together.
shift register
The circuit whose output at any instant depends only on the input present at that instant only
Combinational circuit
The circuit whose output at any instant depends not only on the input present but also on the past output
sequential circuit
This type of circuit has no memory unit
Combinational circuit
This type of circuit has memory unit for stored past output
sequential circuit
An example of this circuit are half adder, full adder, magnitude comparator, multiplexer, demultiplixer
Combinational circuit
Example of this circuit are flip flops, register, counter
sequential circuit
This type of circuit is faster in speed
Combinational circuit
This type of circuit is slower in speed
Sequential circuit
2 categories of sequential circuits
- Asynchronous
- Synchronous
Output changes at discrete interval of time. It is a circuit based on an equal state time or a state time defined by external means such as clock.
Synchronous sequential circuit
Output can be changed at any instant of time by changing the input. It is a circuit whose state time depends solely upon the internal logic circuit delays.
Asynchronous sequential circuit
A circuit that changes from 1 to 0 or from 0 to 1 when current is applied. It is one bit storage location
basic flip flop
SR flip flop is also called
SR latch
this circuit is used to overcome invalid state of the SR flip flop
clocked SR flip flop
Modification of the clocked SR flip flop
D flip flop
refers to a periodic signal where the ON and OFF times do not need to be the same
Clock signal
Types of triggering
- Level triggering
- Edge triggering
The circuit is only activated in whenever the clock pulse happens to be at any particular level
Level triggering
Types of level triggering
- Positive
- Negative
This transition or triggering either occurs from Logic High
to Logic Low or from Logic Low to Logic High
Edge triggering
Types of edge triggering
- Positive
- Negative
a device that selects between several analog ordigital input signals and forwards the selected input to a single output line.
multiplexer
Multiplexer is also known as
data selector
In multiplexer the selection is directed by a separate set of digital inputs known as
select lines
It takes a single input signal and routes it to one of many output lines
demultiplexer
Demultiplexer is also called as
data distributor
is a multiple-input, multiple-output logic circuit that converts coded inputs into coded outputs, where the input and output codes are different.
decoders
Types of decoders
- Binary decoders
- BCD to 7 segment decoders
- Demultiplexers as decoders
are devices that convert information from one format or code to another, typically for standardization, speed, secrecy, or compression.
encoder
are sensors that detect position and speed by converting rotational mechanical displacements into electrical signals and processing those signals
rotary encoders
Types of encoders
- Rotary encoders
- Absolute encoders
- incremental encoder
