9 Differences Between DRAM & SDRAM

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Though the purpose of both these types of RAMs is the same and both of them stores and accesses data in and from the memory in almost the same way, there is some difference between a regular Dynamic RAM and a Synchronous Dynamic RAM.

You must know these differences as that will help you in making the right choice, if you have to. In this article, those differences are compiled which will make you more knowledgeable about a regular and a synchronous DRAM in a much better way.

KEY TAKEAWAYS

  • Dynamic Random Access Memory is a memory but the Synchronous Dynamic RAM is an interface.
  • The DRAM is an asynchronous older technology but the SDRAM is synchronized and is a newer technology.
  • Since the Dynamic RAM lacks instruction pipelining, it cannot perform at a high speed like the SDRAM.

The 9 Differences Between DRAM and SDRAM

Differences Between DRAM and SDRAM

1. Full Forms

DRAM is the short for Dynamic Random Access Memory, while SDRAM is the short for Synchronous Dynamic Random Access Memory.

2. Types

Dynamic RAM is actually a type of memory.

On the other hand, technically, the Synchronous Dynamic RAM is simply an interface.

3. Synchronicity

The Dynamic Random Access Memory is asynchronous in nature.

On the other hand, just as the name suggests, an SDRAM is synchronized with the clock of the computer.

4. Age

The Dynamic RAM follows an older technology having been introduced in 1967 by Robert H Dennard.

On the other hand, the first Double Data Rate SDRAM was first introduced by Samsung in June 1998 which makes it quite a new technology in comparison to regular DRAM.

5. Efficiency

The Dynamic RAM is quite efficient and a good solution to store data in a computer but not as efficient in comparison to the SDRAM.

On the other hand, it is the synchronous nature of the SDRAM that offers a higher efficiency and performance.

6. Data Transfer

In the Dynamic RAM, the operation is asynchronous. This means that the clock of the computer sends the data as soon as it gets the same from the user interface.

On the other hand, in the Synchronous Dynamic RAM instructions are sent more efficiently since the synchronous nature of it joins a pipeline of other instructions that are being processed by the computer.

7. Speed

The Dynamic RAM cannot operate at a higher speed in comparison to the SDRAM.

On the other hand, due to the pipelining of instructions in the computer, the Synchronous Dynamic RAM receives the next command before it has completed processing the preceding command. This allows it to perform at a much higher speed.

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8. Working Process

The regular Dynamic RAM stores data in the capacitor and the transistor helps in accessing them.

On the other hand, the Synchronous Dynamic RAM works simultaneously with the signal sent by the clock pulse and typically uses the Double Data Rate or DDR method.

9. Advantages

The main advantages offered by regular Dynamic RAM include its higher density levels, higher data storing ability and being able to delete or refresh while a program is running.

On the other hand, the advantages of Synchronous Dynamic RAM include higher speed of operation and its ability to use both rising and falling edges of the clock cycle.

Which is More Useful – DRAM or SDRAM?

Well, DRAM and SDRAM both have distinguishing features which is why it is a bit hard to label one as more useful than the other straightaway.

Still, considering all the differences above, the Synchronous Dynamic RAM is slightly more preferable than a regular Dynamic RAM.

Also, when you consider the other important facts that are mentioned hereunder, it will be quite clear to you why people favor SDRAM over regular DRAM.

Dynamic RAM is used in most of the modern computers being the least expensive type of RAM.

However, requiring a constant supply of energy in order to maintain its electrical state and the chances of losing all data stored in it in case of losing the charge makes it quite a risky option.

Another point of concern is that the CPU typically cannot access the data stored in the Dynamic RAM when it is being refreshed.

This means it has to wait till the refreshing process is completed, which makes it quite slow to perform.

Still, Dynamic RAM has been used for decades and is also at the core of the 4th generation Double Data Rate or the DDR4 RAM that normally you find in the market today.

The operation of the Dynamic RAM is quite simple wherein the capacitor stores the data represented by a charge and the transistor controls the flow of electrical energy in and out of that capacitor.

This transistor is activated by the word line itself and acts as a type of a control gate.

As for the bit cells, these are usually arranged in groups in a single large collection of cells.

Each of these arrays is made up of rows and columns and is usually 2 dimensional in nature.

Dynamic RAMs usually do not have a central address bus and is typically accessed through the RAS-CAS cycle and a part of the address bit is used for different purposes such as:

  • To affirm the address bus
  • To run the address strobe
  • To wait till it is completed
  • To put the remaining address bits on the bus and
  • To run the column address strobe eventually.
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The correct row or column is actually selected physically by the circuitry while running the RAS or CAS.

The control information passed in the RAS and CAS cycle is then converted into internal control signals by the special decoder circuitry.

These signals are used to open or close the transistors with the required data.

The problem with Dynamic RAM is in its implementation, which is very slow in accessing random places in the memory and the interface needs a new transfer or RAS-CAS cycle to be initiated for each data transaction.

Therefore, the concept of ‘burst mode’ was implemented in the memory and new interfaces such as EDO, SCR, and FPM came into the market and each of them used the same DRAM bit cells.

This means that the fundamental memory did not change. What changed ideally is the circuitry of the memory itself and the way in which data is accessed in it.

This, however, changed the sequential transfer speeds significantly and resulted in lower latency during accessing any data from a row.

Some of the unique features of the Dynamic RAM are:

  • The Dynamic RAM uses one transistor to store the data in a single capacitor.
  • The capacitor in the Dynamic RAM however loses its charge and therefore will lose the data stored in it unless it is recharged periodically. That is why this particular type of RAM is called ‘dynamic.’
  • The Dynamic RAM does not need to wait for synchronization with the clock of the computer system as it is required by the Synchronous Dynamic RAM.

The design of the Dynamic RAM which consists of the access transistors and storage capacitors along with the developments in the semiconductor processes have made it the cheapest memory that is available for storing data.

It is mainly for this reason that Dynamic RAM is used today as the main memory of the computer more often than not.

However, over the years, the technology of Dynamic RAM has gone through a number of significant improvements.

These changes and introductions have resulted in a lot of notable improvements such as:

  • A much smaller cell
  • A synchronous architecture and
  • DDR or Double Data rate topologies.

As a result of these improvements, the new and more improved Dynamic RAM modules offer several benefits such as:

  • A much increased clock rate
  • A much lowered cost-per-bit and
  • A much reduced overall dimensions.

However in spite of all these developments, it was seen that a memory, when synchronized, can operate much faster.

This brought in the new type of RAM, the Synchronous Dynamic Random Access Memory.

Though the SDRAM uses the same DRAM bit cells, everything in it is now controlled by the clock.

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Along with several improvements, the tighter timing constraints made these memory modules much more efficient in accessing data because it is synchronized with the system bus.

Therefore, it can run at significantly higher clock speeds.

The Synchronous Dynamic RAM is one of the most popular forms of RAMs preferred in a computer due to its higher efficiency and much higher speed in comparison to the regular Dynamic RAM.

One of the most notable and distinguishing factors of the Synchronous Dynamic RAM architecture is that the memory is separated into a number of segments of equal size.

These segments are often referred to as memory banks which can perform access commands concurrently.

This allows the SDRAMs to operate at a much higher speed than a standard Dynamic RAM module.

Another significant attribute of the Synchronous Dynamic RAM architecture is the concept of pipelining which makes a major contribution in its operational speed, as said earlier.

This pipelining concept of SDRAM allows one memory bank to stay in its pre-charging state while going through access latency when another memory bank may be engaged in reading the data.

This means that the memory chip will output data constantly.

In other words, this specific architecture that consists of several memory banks in the SDRAMs allows them to be accessed simultaneously for different rows.

Therefore, in short, it can be said that Dynamic RAM and Synchronous Dynamic RAM are almost the same thing. Until the mid 1990s, all DRAMs were asynchronous and since then SDRAM came into existence and took over from it.

The bottom line is: data transfer in SDRAM is much faster in comparison to a regular DRAM and this single point is strong enough for Synchronous Dynamic Random Access Memory to excel and to be more preferable over the Dynamic Random Access Memory.

Conclusion            

So, with the comparison and differences between Synchronous Dynamic Random Access Memory and a standard Dynamic Random Access Memory now known and clear to you, thanks to this article, it will be much easier for you to differentiate between the two types and make the right choice.

About Dominic Cooper

Dominic CooperDominic Cooper, a TTU graduate is a computer hardware expert. His only passion is to find out the nitty gritty of all computers. He loves to cook when he is not busy with writing, computer testing and research. He is not very fond of social media. Follow Him at Linkedin