Difference Between SRAM and DRAM

Overview

RAM, or Random Access Memory, comes in two primary types: SRAM (Static RAM) and DRAM (Dynamic RAM). It’s essential to understand the difference between SRAM and DRAM. SRAM is known for its superior speed and lack of need for constant refreshing, making it suitable for cache memory. On the other hand, DRAM is more commonly used due to its cost-effectiveness and higher storage capacity, with DDR3 being a well-known example. SRAM’s speed makes it ideal for cache applications, while DRAM strikes a balance between performance and affordability, making it the preferred choice for system memory. This understanding is vital for informed decisions in computer architecture and system design.

What is RAM?

RAM stands for Random Access Memory. RAM is a type of computer memory that allows us to access any byte of the memory without the need to access the previous bytes as well.

RAM is a type of volatile memory, i.e., it needs a constant power supply to retain the data stored in it. If the power supply is lost, the data stored in the RAM erases instantly. This is why RAM is also called cache memory or temporary memory of a computer.

RAM is of two types, SRAM and DRAM.

Let us understand each of these types.

What is SRAM?

SRAM stands for Static Random Access Memory. The data in an SRAM is stored in transistors. Each bit of memory is stored using Bistable Latching Circuitry in this RAM. The data is stored using the six transistors memory cells.

Since SRAM uses transistors to store data, it requires a constant power supply. Because the power supply is constant, SRAM does not need to be refreshed in order to remember the data being stored in it. SRAM is called a static RAM because no action is required to recall the stored data.

SRAMs are used in cache memories since they consume less power and have fast access speeds.

Characteristics of Static RAM

Following are the characteristics of Static RAM:

They use transistors to store data.
They consume less power than DRAMs.
They have a small cycle length.
They are usually used as cache memory.
They are significantly faster than DRAMs.
They occupy more space than DRAMs.
They are expensive to manufacture.

What is DRAM?

DRAM stands for Dynamic Random Access Memory. DRAM is the most widely used RAM in computers. The data in a DRAM is stored in capacitors. Each bit of data is stored in a separate capacitor inside a particular integrated circuit. The value 1 denotes that a capacitor is charged, while the value 0 denotes that a capacitor is discharged.

DRAMs have a high power consumption because capacitors tend to leak charge even when they are supplied with continuous power. Because of the charge leakage, the power supply in DRAMs needs to be refreshed regularly in order to retain the data stored in them. This is why these RAMs are called Dynamic.

DRAMs are used in main memories since they are cheap and have high memory capacities.

Characteristics of Dynamic RAM

Following are the characteristics of Dynamic RAM:

They use capacitors to store data.
They are cheap to manufacture.
They are usually used as the main memory.
They need to refresh in order to retain the data stored.
They are slow compared to SRAMs.
They consume more power than SRAMs.
They have a short data lifetime.

Key Difference Between SRAM and DRAM

The key difference between SRAM (Static Random-Access Memory) and DRAM (Dynamic Random-Access Memory) lies in their construction and performance characteristics. SRAM is built using flip-flop gates, which store data without the need for constant refreshing, making it faster but more expensive and power-hungry. DRAM, on the other hand, uses capacitors to store data, requiring periodic refreshing to maintain information, which results in slower performance but lower cost and power consumption. While SRAM is often used for cache memory due to its speed, DRAM is more commonly employed for main system memory due to its cost-effectiveness and capacity.

Difference Between SRAM and DRAM

Following are the differences between SRAM and DRAM.

Differentiating Parameter	SRAM	DRAM
RAM Application	SRAM is usually used as L2 and L3 cache units in a CPU.	DRAM is usually used as the main memory in computers.
Memory Capacity	Typically, SRAMs have a size of 1MB to 16MB.	Typically, DRAMs have a size of 4GB to 16GB in PCs.
Cost	SRAMs are more expensive than DRAMs.	DRAMs are cheaper and more cost effective than SRAMs.
Placement of RAM	SRAM is either present on the processor or it is fixed between the processor and the main memory of a device.	DRAM is present on the motherboard of a device.
Speed	SRAM is faster than DRAM since it has a faster access time.	DRAM is slower than SRAM.
Number of Transistors	SRAM has six transistors.	DRAM only has a single transistor.
Density	SRAM has a low density.	DRAM is highly dense.
Power Consumption	SRAM has a much lower power consumption compared to DRAM.	DRAM has a high power consumption.
Simplicity	SRAM offers easy to build interfaces in order to access the memory.	DRAM is more complicated compared to SRAM.
Construction and Design	Construction and design of SRAM is a complicated process because of the various types of transistors in it.	Construction and design of DRAM is much easier compared to SRAM because of the smaller number of transistors in it.
Charge Leakage	There is no issue of charge leakage in SRAM.	Because of the capacitors used in DRAM, it faces the problem of charge leakage.
Data Retention	SRAM does not suffer from data loss when powered off.	DRAM requires periodic refresh cycles to maintain data, and data is lost when powered off.
Use Cases	SRAM is suitable for cache memory due to its speed and lower latency.	DRAM is commonly used for main system memory due to its cost-effectiveness and capacity.

Advantages and Disadvantages of Static RAM

Advantages

SRAM is much faster in operation than DRAM.
SRAM has a low power consumption compared to DRAM.
SRAM is used for creating speed sensitive cache.
SRAM does not need to refresh the memory contents.

Disadvantages

SRAM is very expensive.
SRAM offers a low storage capacity.
SRAM has a low memory density.

Advantages and Disadvantages of Dynamic RAM

Advantages

DRAM is cheaper compared to SRAM.
DRAM offers a high storage capacity.
DRAMs are easy to design.
DRAM has a high memory density.

Disadvantages

DRAM is slower compared to SRAM.
DRAM has a high power consumption.

Conclusion

The article delves into the fundamental differences between SRAM and DRAM, two key types of RAM essential for modern computer systems.
SRAM is noted for its speed, low power consumption, and suitability for cache memory, while DRAM is favored for its cost-effectiveness and high storage capacity in main memory.
The comparison between SRAM and DRAM underscores critical distinctions in terms of cost, speed, power consumption, and design complexity.
This knowledge equips professionals in computer architecture and system design to make informed decisions when selecting RAM types that align with specific performance and cost-efficiency goals.
Ultimately, understanding SRAM and DRAM plays a pivotal role in achieving the desired balance between computing system performance and cost-effectiveness.