SDRAM vs. SRAM: How Do They Compare?

Key Points

• RAM stands for Random Access Memory, while SDRAM, stands Synchronous Dynamic Random Access Memory.
• SDRAM consumes more power compared to RAM.
• SDRAM functions with greater speed compared to RAM.

You already know how important RAM is to a computer. Without RAM, a computer wouldn’t be much of anything beyond a big, fancy paperweight.

You also know that it’s important to pay attention to the different amounts of RAM available to you. The amount of RAM your computer has is directly proportional to the number of tasks it can handle.

But what about the different types of RAM? Take SDRAM and SRAM, for instance. What are they, what do they do and what sets them apart—not just from each other, but from standard RAM, too?

In order to make sense of what SDRAM and SRAM are, it’s worth making a full comparison between the two. Keep reading for the full breakdown of these two memory systems.

SDRAM vs. SRAM: Full Comparison

First and foremost, SDRAM and SRAM are united by one key factor: they’re both types of random-access memory.

They can both be defined as semiconductor devices that play an essential role in the integrated chips that store a computer’s processor. Both are used to store information that is vital to a computer’s operating system, and both are used to help a computer perform at high speeds.

However, the similarities between the two more or less stop there.

While both SDRAM and SRAM are types of random-access memory, they are not exactly interchangeable. The very architecture of the two differs.

While SDRAM relies on transistors and capacitors arranged in a series of repeating circuits, with each circuit forming one bit, SRAM relies on an array of transistors in a circuit to form the same.

SDRAM is much smaller than SRAM. If you were to place identically sized SDRAMs and SRAMs next to one another, the former would be able to hold far more memory than the latter.

More Differences between SDRAM and SRAM

Beyond their physical differences, SDRAM and SRAM have differences in technological performance.

SDRAM must be constantly refreshed, always referring back to the microprocessor clock and synchronizing with the computer’s system bus before responding to a command. SRAM, on the other hand, is static. That means it doesn’t need to be refreshed as SDRAM does. For this reason, SRAM is technically faster than the SDRAM (albeit much larger and more expensive).

Additionally, the SDRAM eats up a lot more power than the SRAM because of all that constant refreshing going on.

Every few nanoseconds, the SDRAM is given a small electronic charge. This adds up to more power consumption in the long run. While it’s not the kind of difference that’s going to run up your energy bill, it’s still a difference nonetheless.

Temperature plays a part in this, as well. SDRAM will have a higher refresh at higher temperatures, while SRAM stays stable across a wide range of temps.

SDRAM vs. SRAM: A Side-by-Side Comparison

SDRAM vs. SRAM: 5 Must-Know Facts

• SRAM is static, while SDRAM is dynamic. This means that the latter needs constant refreshing, while the former does not.
• Neither SRAM nor SDRAM is volatile. This means that, if they lose power, they also lose their data.
• SRAM is much more expensive than SDRAM.
• SRAM chips are trusted in everything from smartphones, toys, and automobiles to countless other consumer electronics. Conversely, SDRAM chips are mainly reserved for a computer’s main memory source.
• SRAM can fit a handful of gigabits on a single chip. Alternatively, SDRAM can only fit a few tens of megabits on a single chip.

History of SDRAM

At the outset of SDRAM in the early 1970s, this specific kind of RAM was typically synchronized with the CPU clock. It was primarily used alongside early versions of the microprocessor.

Then, around the mid-1970s, SDRAM became DRAM. In other words, it dropped the ‘synchronous’ part and collectively shifted toward an asynchronous design instead. This collective decision lasted throughout the remainder of the ’70s and into the ’80s. Then, in the 1990s, the tech world decided it was time to return to synchronous DRAMs. There was another collective shift, and SDRAM has stayed synchronous ever since.

Samsung made the first SDRAM available for consumers to purchase in 1992. To fabricate its chips, they used what’s called a CMOS, or a complementary metal–oxide–semiconductor. Called the KM48SL2000 memory chip, this early SDRAM had a capacity of 16MB and entered into mass production in 1993.

This was a pivotal moment in SDRAM history: the industry had just begun its shift back to a synchronous design. The arrival of Samsung’s SDRAM helped facilitate this return to synchronous dynamic RAM.

By the turn of the new millennium, thanks in part to Samsung, SDRAM had successfully made a full and triumphant return. New technology had almost entirely done away with DRAM. The driving factor behind this shift back to SDRAM had everything to do with better performance. While latency is not exactly lower than the asynchronous alternative, SDRAM has much faster access times than plain old DRAM.

These days, almost all SDRAM must comply with the manufacturing standards set forth by JEDEC—an independent association made up of individuals in the electronics industry. They collectively work by a certain set of interoperability standards that allows all SDRAMs to be on the same page, technologically speaking.

JEDEC officially put its first SDRAM standards into place in 1993, the same year Samsung’s product entered mass production.

The Invention of SRAM

SRAM actually predates SDRAM by about a decade. The first instance of SRAM—Fairchild Semiconductor‘s semiconductor bipolar SRAM—was invented in 1963 by a man named Robert Norman. One year later, Fairchild Semiconductor unveiled the MOS SRAM. A whole slew of alternate SRAMs would come and go in the decades that followed, from nvSRAM to PSRAM and everything in between.

At this point in the 1960s, SRAM was a huge departure from the magnetic-core memory that was seen as the standard of the time. However, SRAM was not immediately latched onto like the SDRAM was because of its need for six MOS transistors for every one bit of data. (That’s a lot of MOS transistors). For this reason, SRAM didn’t hit the commercial market until 1965 with the release of IBM‘s SP95 memory chip.

Arnold Farber and Eugene Schlig, the two IBM employees behind the SP95, used a transistor gate and tunnel diode latch to create a hard-wired memory cell.

This latch is what gives SRAM its so-called flip-flop, allowing the circuit to alternate between two stable states. To save you the headache of trying to understand the actual physics of this technology, we’ll keep it at this: As soon as a flip-flop stores a single bit, it will hold onto that bit until an opposite bit is stored. It’s a very simple data storage method that comes at an exceptionally high price, and as such, it’s not nearly as popular or useful as SDRAM.

How RAM Types Have Changed

An effective way to outline the difference in complexities between SDRAM and SRAM is to detail the number of changes each has gone through over the years.

Since SRAM’s invention in 1963, this type of RAM underwent a few decades of tweaks and upgrades before ultimately settling on a final iteration in 1995. This version of SRAM became widely used for CPU caches, and it hasn’t been altered once in the decades since. What’s more, the 1995 iteration still utilizes the same number of transistors as the original 1960s version.

SDRAM, on the other hand, has undergone almost incessant upgrades and improvements since first emerging in the early 1970s.

Beyond the major cultural shift from synchronous to asynchronous and back again, SDRAM has continually been changing and adapting with the times for nearly 60 years. The most recent upgrade happened in 2018 when Samsung unveiled the 128Gb DDR4 SDRAM.

When looking at SDRAM and SRAM, this comparison of how the two have changed over the years is perhaps the most enlightening.

SDRAM vs. SRAM: Which Is Better?

At the end of the day, iSDRAM and SRAM have drastically different physical and technological makeups.

While it’s true that both are types of RAM, are nonvolatile forms of memory, and are essential to a computer’s ability to function, SDRAM and SRAM have very different uses in today’s world. For instance, SRAM is the preferred RAM for smartphones, while SDRAM is preferred for computers.

With that being said, it’s still possible to take an objective judgment based on the information we’ve discussed thus far.

Here are the facts: SRAM is faster and uses less power, but it comes at a higher price and a larger size. SDRAM, on the other hand, might have a slower response time and higher power consumption, but its cheaper price and smaller size make it the preferred choice for a computer system.

In the eyes of most, this makes SDRAM the superior form of RAM.

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