Types of RAM | An Overview of Various Forms of RAM

RAM (Random Access Memory) is a common piece of hardware used in all modern computing devices like computers, smartphones, etc. It is an essential part that determines the performance of the devices. Like any other electrical system, RAM has come a long way with upgrades and modifications. It is used in various types of devices as well. For this reason, there are many types of RAM. In this article, we’re going to explain the types of RAM generally used in systems.

What is RAM

RAM is a type of memory used in computers and smartphones that stores temporary information while running an operating system or a program. The information comes from the processor. We can find various volumes of RAM ranging from 128MB to 32GB or more. The amount of RAM directly affects the performance of a device.

To run an operating system, a minimum amount of RAM is needed at all times. Beyond that, for each action we take on a device, like launching a program or running a game, different amounts of RAM are needed to do the task. You can specifically allocate RAM to a program or preserve it if needed. You can also overclock RAM to enhance its performance significantly.

A device with a sufficient amount of system memory (RAM) can perform relatively well while running heavy software or multitasking because more amount of memory is available for them to run properly. For this reason, the RAM amount is a criterion for performance for computers and smartphones. While computer RAM can be upgraded by buying new improved ones and attaching them to the motherboard, smartphone RAM isn’t upgradable as of now. You can clear RAM by taking some steps.

Types of RAM

There are various types of RAM used in different devices. RAM production companies upgrade their RAM continuously to gain more power efficiency and better performance. There are different types of memory used in desktop computers, laptops, and smartphones as well. RAM and ROM both come in various similar types. As a whole, we can differentiate RAM type into 2 categories.

1. SRAM (Static RAM)
2. DRAM (Dynamic RAM)

SRAM

Static RAM (SRAM) is a volatile memory, meaning that as soon as power is turned off, the data is removed. It is more expensive than DRAM but much faster. For this reason, SRAM is generally used in the CPU cache. The cache is a fast and small form of memory that is situated close to the processor, for instantaneous data transfer. There are 3 types of cache formed by SRAM:

• L1 Cache, or Primary Cache.

This type is embedded into the processor and is the smallest and fastest among these.

• L2 Cache, or Secondary Cache

This has more space than the L1. It can either be embedded or can be externally connected to the processor.

• L3 Cache, or Specialized Cache.

This is the slowest among the three, yet still twice as fast as the DRAM. It is used in multicore processors.

DRAM

Dynamic RAM (DRAM) is also a volatile memory where a capacitor is continuously charged and discharged, forming 2 states. To prevent data loss, this type of memory is always refreshed, unlike the SRAM that doesn’t require refreshing. DRAM is what we know as traditional RAM. It is cheap, comes with many types, and can be upgraded in many systems. In general, DRAM is of 2 types:

1. Asynchronous DRAM
2. Synchronous DRAM (SDRAM)

Asynchronous DRAM

This type of DRAM is one of the oldest forms of RAM which aren’t used today. Here, the memory isn’t synchronized with the CPU clock cycle. So, often times when data becomes available in RAM, the CPU isn’t ready. A latency occurs each time this happens, making the asynchronous DRAM quite slow.

Synchronous DRAM (SDRAM)

In the SDRAMs, the clock cycle of the CPU is synchronized with the memory. So, CPU is always ready for when data becomes available on the memory bus. Here, the input-output clock frequency between the CPU and memory controller, and the internal frequency of RAM are the same. This prevents the latency significantly, making the DRAM perform much faster. We can differentiate the SDRAM into 2 categories:

1. Single Data Rate- Synchronous Dynamic RAM (SDR- SDRAM)
2. Double Data Rate- Synchronous Dynamic RAM (DDR- SDRAM)

SDR- SDRAM

Here, “Single Data Rate” means that data transfer occurs once at every peak of the clock cycle. The SDR- SDRAM operates at 3.3V, which is very high as of modern standards. This form of RAM comes with a PC-100 module, meaning that the frequency is 100MHz per bit. So, for a 64-bit wide bus, the data rate is 100MHz times 64-bit, or 800 megabytes per second.

DDR- SDRAM

DDR memories and their later generations are used in computers and smartphones still now. DDR means “Double Data Rate”. Here, data transfer occurs both at the peak point and the lowest point of a cycle, as opposed to only once in SDR- SDRAM, making the bandwidth twice than before. You can check RAM info through built-in commands. DDR memories come with various types too:

1. DDR1
2. DDR2
3. DDR3
4. DDR4

DDR1

These are the first type of DDR- SDRAM, operating at 2.5V. Due to the 2-bit data transfer per cycle, this is called “2-bit prefetch”. The internal clock frequency is 133-200 MHz, meaning the data rate will be twice, 266-400 MT/s (mega-transfer per second). For 64-bit memory, this gives a bandwidth of 3200 MB/s. So, DDR1 comes with PC-3200 modules.

DDR2

Here, the operating voltage is slightly reduced to 1.8V. The internal clock frequency is the same as previous, up to 266.67MHz, but it has a 4-bit prefetch. The data transfer rate of DDR2 is 400-1066.67 MT/s, and it comes with PC2 modules (PC2-3200, PC2-6400, etc.).

DDR3

These are currently used by the greatest number of users. DDR3 memory operates at 1.5V. Another variant, the DDR3L (DDR3- low voltage) operates at 1.35V. It has an 8-bit prefetch and comes with PC3 modules. The internal clock frequency is slightly increased to a maximum of 266.67MHz as opposed to the 200MHz of previous versions. To get more info about DDR3 and DDR3L, click here.

DDR4

This is the latest version of RAM used in high-end and latest motherboards. DDR4 operates at 1.2V with an 8-bit prefetch, the same as DDR3. But it has a much higher internal frequency (133-266.67MHz). It has PC4 modules and a data transfer rate of 2133-4266MT/s. There are various ways you can check your RAM speed.

Types of RAM in Terms of Packaging

We can differentiate 4 types of memory in terms of packaging type:

• DIP (Dual Inline Package)

These are the oldest type, currently not used in modern devices.

• SIMM (Single Inline Memory Module)

Here, the memory chips are soldered onto 1 piece of PCB board. Connecting pins are situated on only 1 side of the PCB. So, SIMM memory can provide 32-bits of the data bus. To get 64-bits, we have to use 2 SIMM boards parallelly.

• DIMM (Dual Inline Memory Module)

DIMM memory has a 64-bit wide bus and comes with pins on both sides. DIMM memory is used in desktop computers. It has the highest pin counts. A DDR3 DIMM memory has 240 pins.

• SODIMM (Small Outline Dual Inline Memory Module)

SODIMMs are used on laptops and notebooks for their small size. These come with relatively less pin count. A DDR3-SODIMM has 204 pins.

All these types come with different pin locations, so DDR memories are neither forward nor backward compatible.

RAM of Smartphones and Graphics Cards

Computers and laptops can use bigger memory sticks with higher power requirements because of their bigger size and plug-in supports. But for smartphones or equivalent devices, battery life and space is a major issue. For this, these types of devices use the LPDDR (Low-Power DDR) or MDDR (Mobile DDR) type of memory. As of now, we have LPDDR1, LPDDR2, LPDDR3, LPDDR4, and LPDDR4X memories available. The latest ones are used in flagship phones while normally we see the LPDDR3 ones.

Graphics cards use another type of RAM, known as the GDDR (Graphics DDR) that works as a storage for VRAM or video memory for them. GDDR memories are different in structure with complex methods because of their high graphical data transfer requirements. Currently, we have GDDR1 to GDDR5 versions for graphics cards.

Conclusion

In this article, we’ve briefly discussed the types of RAM used in computers, smartphones, and other devices. There are a lot of other types available too for specialized usage and some too rare to consider. It is important to know about the basic types of memory before buying or upgrading them. Almost all the desktops and many laptops support RAM upgrading, but this is fixed for smartphones.