Definition: DRAM stands for Dynamic Random Access Memory. DRAM is a technical term for a type of random access memory (RAM) that can retain its contents only for a very brief period (measured in milliseconds) and must, therefore, be continually refreshed by reading its contents at short intervals.
DRAM makes use of a capacitor and stores every bit of data on the different-2 capacitor. It is the most efficient way to store data as the space required for the storage of data is less as compared to the static RAM. The power requirement of the DRAM is more as we have to keep the capacitors refreshed so that they can continue their charge as the leakage of charge is there within the capacitor.
Despite the fact that DRAM requires extra REFRESH circuitry to design into the computer’s PROCESSOR BUS, it has until recently been the most widely used type of memory because it is so much cheaper to manufacture than non-volatile STATIC RAM. DRAM is the most common type of memory found on SIMMs.
The CELLS that store the bits in a DRAM chip are simple single-transistor CAPACITORS (whose charge leaks away, hence the refresh requirement) and more of them can pack onto a single chip than the multi-transistor cells used in STATIC RAM, reducing the cost per megabyte. DRAM is only now falling out of favor – on the grounds of speed rather than price because it cannot read fast enough to keep up with the latest generations of the microprocessor.
It is the most common type of RAM that used on our computers, servers, and workstations.
We’ll be covering the following topics in this tutorial:
Types of DRAM
SDRAM
The full form of SDRAM is Synchronous Dynamic Random Access Memory. It works according to the clock synchronization, and it synchronizes with the bus, which is present in CPU of the system. It is faster than the DRAM.
RDRAM
The full form of RDRAM is Ram bus Dynamic Random Access Memory. As the name implies, it developed by Rambuys Inc. its operating speed is more as compared to the other types of DRAM.
Asynchronous DRAM
As its name implies, asynchronous DRAM does not work according to the synchronization of the clock. Here, the system contains a memory controller and this memory controller synchronized with the clock. Due to which, the speed of the system is also slow.
FPM DRAM
FPM DRAM stands for Fast Page Mode Dynamic Random Access Memory. Nowadays it is out of date as it can only support memory bus speeds up to 66MHz, but designed for the faster version.
EDO DRAM
EDO DRAM stands for Extended Data Out Dynamic Random Access Memory. It designed so that it can provide faster performance and low cost as compared to FPM DRAM.
BEDO DRAM
BEDO DRAM stands for Burst EDO DRAM. The benefit of BEDO DRAM over EDO DRAM is that it can process four memory addresses in one burst or you can say that it saves three clock cycles. BEDO DRAM usage is very less because when it introduced in the market, at that time another memory SDRAM is also launched and it took the market.
Difference between SRAM and DRAM
| SRAM | DRAM |
| • SRAM is Static RAM. | • DRAM is dynamic RAM. |
| • SRAM can do byte-level read and write. | • DRAM can do byte-level writing and multiple-byte level reading. |
| • There is no need of refreshing in SRAM as it operates on the principle of switching the current. | • DRAM needs refreshing as it operates on the principle of charging of the capacitor. |
| • SRAM is expensive. | • It is less expensive than SRAM. |
| • SRAM is faster. | • DRAM is slower. |
| • SRAM used in the cache memory. | • DRAM used in main memory. |
| • The structure of SRAM needs a lot of transistors. | • The structure of DRAM module needs a transistor and a capacitor for storing every bit of data. |
| • SRAM consumes less power than DRAM in sleep mode. | • DRAM requires less power than SRAM inactive state. |
Advantages of DRAM
• Its design is straightforward.
• It has high reliability.
• Its cost is low.
• There is less power dissipation in this.
• It requires less area.
• There is a high integration density in DRAM.
• It has simple memory cell structure.
• It is very dense.
Disadvantages of DRAM
• Inter-signal coupling exists between DRAMS
• There is high power consumption in DRAM.
• Volatile memory of DRAM.
• The data in DRAM require refreshing.
• Its operational speed is relatively low.
• Its manufacturing process is complicated.
Applications of DRAM
• When cost-efficient storage is required, then DRAM is used.
• DRAM used in personal computers.
• It also used in networking.
• It used in battery operated synchronous and asynchronous applications.
• DRAM memories also used for the enhancement of graphics functions of a computer.
Dinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular