Introduction to Registers | What is Shift Register? Types of Shift Registers
Summary
TLDRThis video from the All About Electronics YouTube channel dives into the concept of registers in digital circuits, focusing on their role as memory elements capable of storing multiple bits of data. It explains the basic 4-bit register, its limitations, and how it can be improved with a load signal to control data input without occupying the data bus continuously. The video also introduces shift registers, discussing their ability to shift binary data between connected flip flops and the various methods of data loading and retrieval. The potential applications of shift registers in time delay generation, data conversion, and arithmetic operations are highlighted, with a promise of more detailed exploration in future videos.
Takeaways
- đ Registers are groups of flip flops that can store n-bit data in digital circuits.
- đ D flip flops are commonly used in registers due to their single input and straightforward data storage at clock transitions.
- â° The basic function of a register is to store data at each clock transition and make it accessible at the output.
- đ« A plain register is impractical as it continuously occupies the data bus, which can be problematic in synchronous systems.
- đ An AND gate can be used to control the clock signal to a register, enabling data loading only when required.
- đ The load signal in a register acts as a synchronous input, loading data at clock transitions when high.
- đ§ Registers can be equipped with an asynchronous clear input to reset all flip flops to zero when activated.
- đ Shift registers are a type of register where binary data can be shifted between neighboring flip flops.
- đą Shift registers can be loaded and retrieved in two ways: serially or in parallel, leading to four types based on these combinations.
- đ Shift registers are useful not only for data storage but also for time delay generation, data conversion, and arithmetic operations.
- đ The video promises to cover more details on different types of shift registers in upcoming videos.
Q & A
What is the basic function of a flip flop in digital circuits?
-A flip flop is a basic memory element in digital circuits that can store only one bit of information.
Why are multiple flip flops needed in a digital circuit like a microprocessor?
-Multiple flip flops are needed to store or process data in multiple bits, such as 16, 32, or 64 bits, as these circuits handle more complex data storage and processing.
What is a register in the context of digital circuits?
-A register is a group of flip flops that can store n bits of data, allowing for the storage of larger data sets in a single unit.
Why are D flip flops typically used in registers?
-D flip flops are used in registers because they have only one input, which simplifies the process of storing the input data at the clock transition.
How does the presence of a Master Clock affect the operation of a register?
-The Master Clock, being common between different digital blocks, dictates the timing of data storage in a register. If the register operates at 1 gigahertz, data at the inputs is loaded into the register every nanosecond.
What is the issue with using a register without any control mechanism for data loading?
-Without a control mechanism, the register would continuously load data from the data bus, potentially occupying it for an extended period and preventing other components from accessing it.
How can the data bus be freed up by controlling the register's clock?
-By enabling the clock only when data needs to be loaded into the register through an AND gate controlled by a load signal, the data bus can be used more efficiently and not occupied continuously.
What is the drawback of using an AND gate to control the clock signal in a synchronous system?
-Using an AND gate introduces a propagation delay, causing the register to receive the clock signal after a delay, which is undesirable in synchronous systems where all elements should receive the clock simultaneously.
How does a load signal control the operation of a register?
-A load signal, when high, allows data bits to reach the flip flops through an AND gate and be loaded into the register at the clock transition. When the load signal is low, the register maintains the previous data.
What is a shift register and how does it differ from a standard register?
-A shift register is a type of register where the output of one flip flop is connected to the input of the next, allowing for the shifting of binary data between neighboring flip flops, which is not present in a standard register.
What are the two methods of loading data into a shift register?
-The two methods of loading data into a shift register are serial loading, where new bits are loaded with each clock pulse, and parallel loading, where all bits are loaded simultaneously in a single clock cycle.
What are the four types of shift registers based on data loading and retrieval methods?
-The four types of shift registers are serial IN serial OUT, serial IN parallel OUT, parallel IN serial OUT, and parallel IN parallel OUT, each determined by the method of data loading and retrieval.
What additional applications can shift registers be used for beyond data storage?
-Shift registers can be used for time delay generation, serial to parallel conversion, parallel to serial data conversion, and arithmetic operations.
Outlines
đ Introduction to Registers and Shift Registers
The first paragraph introduces the concept of registers in digital circuits, emphasizing their role as memory elements capable of storing multiple bits of data, unlike flip flops which store only one bit. It explains that registers are groups of flip flops sharing a common clock and typically use D flip flops due to their single input feature. The paragraph also discusses practical issues with using registers, such as data bus occupation and the introduction of a load signal to control data loading, which avoids constant data bus usage. The importance of synchronous operation in digital systems and the avoidance of controlling the clock signal are also highlighted.
đ Understanding Load Control and Shift Registers
This paragraph delves into the mechanism of load signals in registers, illustrating how data bits are controlled and loaded into the register upon a high load signal during a clock transition. It explains the process of maintaining previous data when the load signal is low, facilitated by the feedback from the flip flop's output to its input. The paragraph also introduces shift registers, which differ from standard registers by allowing binary data to be shifted between neighboring flip flops. It outlines the two methods of data loading in shift registers: serial and parallel, and the two methods of data retrieval: serial out and parallel out. The summary also mentions the four types of shift registers based on these loading and retrieval methods.
đ ïž Applications and Future Discussion on Shift Registers
The final paragraph highlights the diverse applications of shift registers beyond mere data storage, such as time delay generation, serial to parallel data conversion, and arithmetic operations. It sets the stage for upcoming videos that will explore different types of shift registers in more detail. The paragraph concludes with an invitation for viewers to engage with the content by asking questions, offering suggestions, and subscribing to the channel for further educational content.
Mindmap
Keywords
đĄRegisters
đĄFlip Flops
đĄShift Registers
đĄD Flip Flop
đĄClock Transition
đĄLoad Signal
đĄData Bus
đĄPropagation Delay
đĄClear Input
đĄSynchronous Digital Systems
đĄSerial and Parallel Data Loading
Highlights
Introduction to registers in digital circuits and their importance as basic memory elements.
Explanation of how flip-flops, as basic memory elements, can store only one bit of information.
Description of registers as a group of flip-flops capable of storing n-bit data.
Diagram of an n-bit register with each flip-flop sharing a common clock.
Use of D flip-flops in registers due to their single input and convenience for data storage.
Functioning of a basic 4-bit register with individual inputs and outputs for each flip-flop.
Challenges of using registers with a common Master Clock in synchronous digital systems.
The concept of data bus occupation and its impact on system performance.
Solution to control data loading into registers using a load signal and an AND gate.
Avoidance of controlling the clock signal in synchronous systems due to propagation delay issues.
Control of register operation by managing data inputs instead of the clock signal.
Introduction of load and clear inputs in registers for data loading and resetting.
Explanation of shift registers and their ability to shift binary data between neighboring flip-flops.
Two methods of data loading in shift registers: serial and parallel.
Two methods of data retrieval from shift registers: serial out and parallel out.
Four types of shift registers based on data loading and retrieval methods.
Practical applications of shift registers in time delay generation, data conversion, and arithmetic operations.
Upcoming detailed exploration of different types of shift registers in future videos.
Invitation for questions, suggestions, and engagement through likes and subscriptions.
Transcripts
Hey, friends welcome to the YouTube channel ALL ABOUT ELECTRONICS. So in this video, Â
we will learn about the registers in the digital circuits. And at the later part of the video, Â
we will also talk about the shift registers. So, so far we have seen the different types of flip Â
flops. And we understood that, this flip flops are very basic memory element in the digital circuits. Â
And we have also seen that, this flip flop can store only one bit of information. Â
But if you take any digital circuit, for example a microprocessor or the microcontroller, Â
then it stores or process the data in the multiple bits. Like 16 bits, 32 bits or 64 bits. Â
So if you want to store this data, then we require multiple flip flops. Â
So this group of flip flops, which can store the n bit of data are called the registers. Â
So this is the diagram of the n bit register. And here, each flip flop is sharing the common clock. Â
So if the n is equal to 4, then we will have the 4 bit register. So this is the very basic type Â
of 4 bit register. Now typically in the register, the D flip flops are used as the memory element. Â
Because as you know, this D flip flop has only one input. And in the D flip flop, whatever input we Â
apply at the input side, the same will be stored in the flip flop at the clock transition. And Â
therefore, it is convenient to use the D flip flop in the registers. So here this B1 B2 B3 and B4 are Â
the inputs of this register. And as you can see, each input is connected to the individual input Â
of the flip flop. So at the clock transition, whatever input is present at these four inputs, Â
the same will be stored in the register at the clock transition. That means this is the very Â
basic type of register, which can store the data at the every clock transition. And if you want to Â
access that data, then that can be also accessed at the output side. But practically, this register Â
is of no use. So let me explain why? Now typically if you see any synchronous digital system, then Â
it has the Master Clock, which is common between the different digital blocks. So let's say, this Â
register is also getting the common Master Clock. And let's say it is operating at the 1 gigahertz. Â
That means the duration of the clock is equal to 1 nanosecond. So we can say that, at every 1 Â
nanosecond, whatever data is present at these four inputs, the same will be loaded into the register. Â
So let's say, we have some data, which we want to store for the 300 microseconds. Â
So here we also need to make sure that, these four inputs, or the inputs of the data Â
bus it's not changing up to 300 microsecond. Because if the data changes before that time, Â
then whatever random input is present at the data bus that will be stored in the register. Â
That means we need to ensure that, the data is available on the data bus up to 300 microsecond. Â
So in a way, here we are also occupying this data bus up to 300 microseconds. Â
And in between, if any other register in the system, wants to access this data bus, then it Â
won't be able to access that data bus. So let's see, what we can do to avoid all these issues. So Â
the one solution is, we can just enable the clock whenever we want to load the data in the register. Â
So for that, we can apply this clock to the resistor through this AND gate. Â
So whenever this load signal is high, then only this clock will be delivered to the register. Â
And whatever data is present at the inputs, the same will be loaded into the register. Â
So whenever this load signal will become low, then this clock will also get disabled. And Â
as you know, whenever there is a no clock pulse, then the flip flop will retain its current state. Â
So in this way, whatever data which is loaded into the register, it will remain as it is. Â
And once again it will change, whenever this load signal is high. Â
So in this way, we are not occupying the data bus over the entire time. Â
But generally this approach is not preferred. And typically anything which controls the clock Â
signal, is usually avoid in the synchronous digital systems. Because here, due to this AND gate,Â
this register will receive the clock after the certain propagation delay. That means there Â
is a propagation delay, between the Master Clock and the clock which is received by the register. Â
And in the synchronous systems, it is preferred that, all the synchronous elements receive the Â
clock at the same time. That means, this approach is typically avoided in the synchronous systems. Â
So rather controlling the clock signal, the operation of the register is controlled by the Â
controlling the data inputs. So this is how, the data bits are controlled using the load signal. Â
So as you can see, whenever this load signal is high, then the data bits B1 B2 B3 and B4 will Â
reach to the flip flop, through this AND gate. And at the clock transition, that data will be Â
loaded into the register. Now whenever this load signal is high, then this load bar will become Â
low. And therefore, the output of the second AND gate will become 0. That means in that case, Â
the second AND gate will remain disabled. Now whenever, this load signal will become low, Â
then the output of this first AND gate will become 0. But now, since the load bar will become high, Â
so this input will become high. And now whatever output is present at the output of the flip flop, Â
the same will be given back to the input. And in this way, the flip flop will hold its Â
current data. That means whenever, you just want to load the new data, then first of all make the Â
data available on this data bus. And then after just enable this load signal. And when this load Â
signal is low, then the register will maintain the previous data. So this is the very basic register Â
with the load input. And here, this load signal is the synchronous input. Meaning that once this load Â
signal is high, then the data will be get loaded into the register, only at the clock transition. Â
So along with the load signal, we can also have the asynchronous clear input. Â
So here as you can see, this clear input is the active low. That means whenever Â
this clear input is low, then all the flip flops in the register will get reset to zero. Â
So if we represent the same circuit in the block diagram, that this is how it can be represented. Â
So here, this B1 to B4 are the inputs, while the Q1 to Q4 are the outputs. Â
And apart from that, we have also this load signal and the clear input. So in this type of register, Â
we can store the data, or we can retrieve the data. But there is another type of register, where Â
it is possible to shift the binary data, between the neighboring flip flops of the register. Â
So this type of register is known as the shift register. So in this type of register, the output Â
of the one flip flop is connected to the input of the next flip flop. So if you see the register Â
circuit, we have discussed so far, in that there is a no interconnection between the flip flops. Â
But in the shift register, the neighboring flip flops are the interconnected. Â
So in the shift register, there are two ways the data can be loaded. The one is the serially. Â
That means at the every clock pulse, the new bit will get loaded into the register. So if we have a Â
4 bit register, then in the four clock pulses, the data will get loaded into the register. So in this Â
type of register, the register has only one input. Now the second method of loading is the parallel Â
load. So in the parallel load, all the bits of the register, will get loaded in the single clock. Â
So if we have a 4 bit shift register, then for the parallel load, this 4 input should be accessible. Â
And by applying the inputs to these four lines, the new data can be loaded into the register Â
in the single clock. That means, there are two possible ways, to load the data into the register. Â
Similarly, there are two ways to retrieve the data from the shift register. Â
And the one is the serial out. So in the serial out, we have only one output line. And at every Â
clock, we can access only, one output bit. So in a 4 bit shift register, to retrieve the data of the Â
register, you will require 4 clock signals. Now the second method is the parallel out. So in this Â
parallel out, we can access all the output bits in The single clock. So if we have a 4 bit shift Â
register, then for the parallel out, all the four outputs of the flip flop should be accessible. Â
So depending on, how the data is loaded into the shift register, and how the data is retrieved, Â
we have total four types of shift registers. That is serial IN, serial OUT. serial IN parallel OUT, Â
parallel IN serial OUT, and parallel IN parallel OUT. So in the first type of Â
register, the data is serially loaded into the register, and it is also taken out serially. Â
Then in this serial IN parallel OUT type of shift register the data is loaded serially, Â
but it can be accessed parallelly. Then in this parallel IN serial OUT type of shift register, Â
the data is loaded parallelly, but it can be taken out serially. And likewise, Â
in this parallel IN parallel OUT type of shift register the data is loaded parallelly, and it Â
is also taken out parallelly. So this is similar to the register, which we have discussed earlier. Â
So these are the four types of shift registers. So apart from the storage, because of its shifting Â
property, these shift registers are also useful in many other applications. Like for the time delay Â
generation, and serial to parallel conversion. Apart from that, they can also be used for the Â
parallel to serial data conversion, as well as in the arithmetic operations. Â
So in the upcoming videos, we will learn in detail about this different types of shift registers. But Â
I hope in this video, you got the basic idea about the register, and this shift register. Â
So if you have any question or suggestion, then do let me know here in the comment section below. Â
If you like this video, hit the like button, and subscribe to the channel for more such videos.
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