Types of RAM and its Uses

Random-Access Memory (RAM) is a component used in devices for the storage purposes. The data that is stored in RAM is read in terms of bursts. Depending on the way the data is maintained, RAM chips are classified. Basically, RAM is classified into Static RAM (SRAM) AND Dynamic RAM (DRAM).

Static Random-Access Memory

SRAM uses bistable flip-flops, to store the data in bits. Once the data is written in SRAM, it is stored, and it doesn't have to be refreshed as often as other types of RAM. There are three modes in which a cell, which actually stores data in SRAM, operates. They are Standby, Reading and Writing. Unlike DRAM, SRAM doesn't consume more power.

Types of Static Random-Access Memory

Depending on Data Storage

• Non-volatile: Data is stored, even when the power is off, so that critical information is secured.
• Asynchronous: The data can be stored in the range of 4Kb to 64 Mb. Fast access time is a main characteristic, and so it used as a main memory component in many electronic devices and embedded systems.

Depending on Transistor

• Bipolar Junction Transistor: It is used in Transistor-Transistor Logic (TTL) and Emitter-Coupled Logic (ECL) devices. It consumes more power, but it works very fast.
• Metal Oxide Semiconductor Field Effect Transistor (MOSFET): It is used in Complementary metal-oxide-semiconductor (CMOS) technology based applications.

Depending on Features

• Quad Data Rate: In one complete clock cycle, two words of data is transferred. Separate I/O bus (network that connects all the devices and chips in a computer) is used to read and write data.
• DDR: Common I/O bus is used for data transfer and a single clock is used to control the input and output of data.

Depending on Flip-Flop

• Binary: It comprises mask transistor and latch.
• Ternary: It is designed using 8 transistors or 14 transistors.

Uses of Static Random-Access Memory

• Computers
• Microprocessors
• Digital Signal Processing (DSP) circuits
• LCD screens and printers
• Hard disk and router buffers
• Digital cameras
• Synthesizers
• Cell phones

Dynamic Random Access Memory

Types of Dynamic Random-Access Memory

SDRAM
The change in the input is perceived and quickly responded by SDRAM¹. It is a synchronous interface, which is synchronized with the computer's system bus and its operations is enabled by an input clock signal.

DDR SDRAM
DDR² SDRAM is an Integrated Circuit (IC) chip, which stores data, in a computer. The clock signal used in it is more efficient than the one used in SDRAM, and so the data transfer is made faster. Its interface uses what is referred as double pumping process, which means that the data is transferred during both the upward and downward edges of the clock signal. Its data transfer rate is 1,600 megabytes per second. It is used in computers and mobile phones.

DDR2 SDRAM
DDR2³ SDRAM is the successor of DDR SDRAM. Its power consumption is less as compared to its predecessor and the speed of the data bus is high. The one difference between DDR2 and DDR SDRAM is, the clock speed of former is half that of latter chip. The maximum data transfer rate of DDR2 SDRAM is 3,200 megabytes per second.

DDR3 SDRAM
Compared to its predecessor, DDR3⁴ SDRAM gives high bandwidth, high data transfer rate etc. The data transfer rate of this RAM is 6,400 megabytes per second, which is twice that of DDR2 SDRAM. Its power consumption is 30% lower than DDR2 SDRAM.

DDR4 SDRAM
It is the next generation high bandwidth interface, which is being developed and is expected to get released in 2012. Some of the expected benefits of DDR4⁵ SDRAM is, high data transfer rate, low input voltage, high range of clock frequencies.

DRDRAM
DRDRAM⁶ or RDRAM is a type of SDRAM which known for its high latency, heat output, complexity, and low performance in exchange for its high price. It is used in video game controls and in video cards.

PSRAM
PSRAM⁷ offers the combined benefits of DRAM (high density) and true SRAM (ease of use). It has built-in refresh and address-control circuitry which is very similar to that of SRAM and is used in many embedded systems such as Apple products.

RLDRAM
This is mainly used in networking and caching applications. Applications involving high rate of read/write operations benefits from the use of this chip. RLDRAM⁸ provides random access with high bandwidth.

EDO DRAM
EDO⁹ DRAM can also be called Hyper Page Mode enabled DRAM, provided improved performance by allowing the consecutive operations to overlap. Because of this facility, a new access cycle can be started even when, the output data of the previous cycle is active.

SGRAM
SGRAM¹⁰ is used in graphic adaptors and it can open two memory pages at a time. This chip also offers bit masking and block writing. SGRAM is designed for high performance acceleration purposes which is especially used in video cards.

FPM DRAM
With FPM DRAM¹¹ the reading and writing of data is not delayed due to precharge and accessing the row of the DRAM. This increases the performance of the device.

Long Forms of the Abbreviations

1. SDRAM - Synchronous Dynamic Random-Access Memory
2. DDR SDRAM - Double Data Rate Synchronous Dynamic Random-Access-Memory
3. DDR2 SDRAM - Double Data Rate Type Two Synchronous Dynamic Random-Access Memory
4. DDR3 SDRAM - Double Data Rate Type Three Synchronous Dynamic Random-Access Memory
5. DDR4 SDRAM - Double Data Rate Type Four Synchronous Dynamic Random-Access Memory
6. DRDRAM - Direct Rambus Dynamic Random-Access Memory
7. PSRAM - Pseudostatic Random-Access Memory
8. RLDRAM - Reduced-Latency Dynamic Random-Access Memory
9. EDO DRAM - Extended Data Out Dynamic Random-Access Memory
10. SGRAM - Synchronous Graphics Random-Access Memory
11. FPM DRAM - Fast Page Mode Dynamic Random-Access Memory

Some portion of RAM can be partitioned and is used as hard disk drives to store data. It stores data temporarily and it is used mainly in computer devices. The technology of carbon nanotubes is to be combined with RAM Technology to increase performance. This allows for faster data access, although the data is stored temporarily and it is used mainly in computer devices. Since 1951, when the first RAM was created and marketed, the technology is advancing leaps and bounds. The scientists are, now, working on how to combine carbon nanotubes with the RAM Technology to increase performance.