What is RAM and Different Types of RAM

What is RAM and its types

Do you also want to know what is RAM – What is RAM in Hindi then you have chosen the right post. Hello friends I welcome you Sumit to our MDS Blog, I hope you are healthy and safe. Friends today we are going to talk about RAM.

Nowadays who is not aware of the word RAM. Friends, if you use this smartphone, then you must have heard and read the name of RAM many times. You must have heard many times that your friends tell you to have a good RAM phone.

Have you ever wondered what is RAM and how does it work, how many types are there? If yes, then today’s post is going to be very beneficial for you. Let us know what is RAM?

What is RAM

The full form of RAM is Random Access Memory. It is a hardware device that is usually located on the motherboard of the computer and serves as the internal memory of the CPU.

This allows the CPU to store data, programs, and program results when you switch computers. This is the read and write memory of the computer i.e. information can be written as well as read from it.

RAM is a volatile memory i.e. it does not store data or instructions permanently. When you switch on the computer, the data and instructions from the hard disk are stored in the RAM. Let me explain with an example how RAM works?

For example → when the computer reboots and when you open a program. So the operating system and programs are loaded into RAM. usually from an HDD or SSD.

The CPU uses this data to perform the required tasks. As soon as you turn off the computer, RAM loses data. Hence the data remains in RAM as long as the computer is on and is lost when the computer is turned off. The advantage of loading data into RAM is that reading data from RAM is much faster than reading from hard drives.

In simple words, we can say that RAM is like short term memory of a person and hard drive storage is like long term memory of a person.

Short term memory remembers things for a short time. Whereas long term memory remembers for a long period. Short term memory can be refreshed with the information stored in the long term memory of the brain.

A computer also works in the same way. When the RAM is full, the processor goes to the hard disk to overlay the old data in RAM with the new data. It is like a reusable scratch paper on which you can write notes, numbers etc. with a pencil. If you don’t have space on the paper, you can erase what you no longer need.

RAM also behaves like this. Unnecessary data on RAM is removed when it is full and replaced with new data from the hard disk which is required for the current operation

RAM comes in the form of a single chip that is mounted on the motherboard or as a number of chips on a small board connected to the motherboard. This is the main memory of the computer. It is faster to write and read in computer as compared to other memory like Hard Disk Drive (HDD), Solid-State Drive (SSD), Optical Drive etc.

The performance of the computer mainly depends on the size of the RAM or the storage capacity. If the computer does not have enough RAM to run the OS and software programs, it will result in slow performance.

So the more RAM the computer has, the faster it will work. The information stored in RAM is accessed randomly, not in the order of a CD or hard drive, so its access time is very fast.

Type of RAM

There are mainly two types of RAM –

Static RAM (SRAM)
Dynamic RAM (DRAM)

Static RAM (SRAM)

Static RAM (SRAM)is a type of random access memory that retains its state for data bits or data as long as it receives power.

It is made up of memory cells and goes to static RAM as it does not need to be refreshed regularly. Unlike Dynamic RAM, it does not require power to prevent leakage so it is faster than DRAM.

It has a special arrangement of transistors that form a flip-flop, a type of memory cell. A memory cell stores one bit of data. Most modern SRAM memory cells are made of 6 CMOS transistors but lack capacitors.

Access times in SRAM chips can be as low as 10 nanoseconds. Whereas, the access time in DRAM is above 50 nanoseconds.

Apart from this, its circulating time is much less than that of DRAM. Because it doesn’t stop between accesses. Because of these benefits associated with the use of SRAM, it is primarily used for system cache memory and frame buffer on high-speed registers and small memory banks such as graphics cards.

Static RAM is faster because the six-transistor configuration of its circuit maintains the flow of current in one direction or the other (0 or 1)

A 0 or 1 status can be written and read immediately without waiting for the capacitor to fill or exit. Early asynchronous static ram chips used to perform read and write operations sequentially. But modern synchronous static ram chips overlap read and write operations.

The drawback with Static RAM is that its memory cell occupies more space for the same amount of storage space than DRAM, a memory cell on a chip. Because it has more parts than DRAM it provides less memory per chip.

Dynamic RAM (DRAM)

Dynamic RAM (DRAM) is also made up of memory cells. It is an integrated circuit made up of millions of transistors and capacitors. Which is very small in size. Each transistor is lined with a capacitor to form a very compact memory cell so that millions of them can fit on a single memory chip

A transistor is a capacitor in the memory cell of DRAM and each cell represents or stores a single bit of data in its capacitor within an integrated circuit (ic).

Capacitor keeps this information or data as 0 or 1. Transistor, which is also present in the cell, acts as a switch. which allows the electrical circuit on the memory chip to read the capacitor and change its state

To maintain the charge in the capacitor, the capacitor needs to be refreshed at regular intervals. This is the reason why it is called Dynamic RAM as it needs to be constantly refreshed to maintain its data.

Types of Dynamic RAM (DRAM)

Asynchronous DRAM

This type of DRAM is not synchronized with the CPU clock. The drawback with this RAM is that the CPU does not know the exact time at which data is available from the RAM on the input-output bus. The next generation of RAM that overcomes this limitation is known as Synchronous DRAM.

Synchronous DRAM

SDRAM came into existence in 1996. This RAM was synchronized with the CPU clock. This allows the CPU or memory controller to know the exact clock cycle or time or number of cycles after which data is available on the bus.

Therefore the CPU does not require memory access and thus the memory read and write speed can be increased. SDRAM is also known as Single Data Rate SDRAM (SDR SDRAM).

DDR SDRAM

The next generation of Synchronous DRAM is known as DDR RAM. It was developed to overcome the limitations and shortcomings of SDRAM and was used in PC memory in the early 2000s.

In DDR RAM, data is transferred twice during each clock cycle. During the positive edge (rising edge) and negative edge (falling edge) of the cycle.

It is known as Double Data Rate SDRAM (DDR SDRAM). There are different generations of DDR SDRAM which include DDR1, DDR2, DDR3 and DDR4. Today the memory that we use inside desktops, laptops, mobiles etc. is mostly either DDR3 or DDR4 RAM.

Types of DDR SDRAM

DDR1 SDRAM

DDR1 SDRAM is the first advanced version of SDRAM. In this RAM, the voltage was reduced from 3.3 V to 2.5 V. In this, data is transferred during both the rising and falling edge of the clock cycle.

Therefore in each clock cycle, 2 bits are being pre-fetched instead of 1 bit which is commonly known as 2 bit pre-fetch. It mostly operates in the range of 133 MHz to 200 MHz.

In addition, the data rate in the input-output bus is twice the frequency of the clock. Because data is transferred during both rising and falling edge. So, if a DDR1 RAM is operating at 133 MHz then the data rate will be double i.e. 266 mega transfers per second.

DDR2 SDRAM

This is an upgraded version of DDR1. It operates on 1.8V instead of 2.5V. Its data rate is twice the data rate of the previous generation due to the increase in the number of pre-acquired bits during each cycle.

4 bits are pre-fetched instead of 2 bits. The width of the internal bus of this RAM has been doubled. For example – If the input-output bus is 64 bits wide then its internal bus width will be equal to 128 bits. Thus it can double the amount of data in a single cycle.

DDR3 SDRAM

In this version, the voltage has been reduced from 1.8V to 1.5V. The data rate has been doubled compared to the previous generation of RAM as the number of pre-received bits has been increased from 4 bits to 8 bits. We can say that the width of the internal data bus of RAM has been increased by 2 times compared to the previous generation.

DDR4 SDRAM

In this version, the operating voltage has been reduced from 1.5V to 1.2V. But the number of bits that can be pre-fetched is the same as in the previous generation. 8 bits per cycle

RAM’s internal clock frequency is twice that of the previous version. If you are operating at 400 MHz then the clock frequency of the input-output bus will be four times 1600 MHz and the transfer rate equals 3200 mega transfers per second.

Difference Between Static RAM and Dynamic RAM

Static RAM

• It is a static memory. Because it does not need to be refreshed again and again.
• Its memory cell is made of 6 transistors. Therefore its cells occupy more space on a chip and provide storage capacity (memory) as compared to DRAM of the same physical size.
• It is more expensive than DRAM and is located on the processor or between the processor and main memory.
• Its access time is short. About 10 nanoseconds, so it’s faster than DRAM.
• It stores information in a bistable latching circuitry. It requires regular power supply so it consumes more power.
• It is faster than DRAM because its memory cells do not need to be refreshed and are always available. So it is mostly used in registers in CPU and cache memory of various devices.
• Its circling time is short as it does not need to pause between access and refresh.

Dynamic RAM

• This is a dynamic memory. Because it needs to be refreshed continuously otherwise it will lose data.
• Its memory cell is made up of a transistor and a capacitor. So, its cells occupy less space on a chip and provide more storage capacity as compared to SRMs of the same physical size.
• It is less expensive than SRAM and is located on most motherboards.
• Its access time is longer. more than 50 nanoseconds, so it’s slower than SRAM.
• In this, each bit of information or data is stored in separate capacitors within an integrated circuit. so it consumes less power.
• It is not as fast as SRAM. Because its memory cells are constantly refreshed. But still it is used in motherboards because it is cheaper to manufacture and requires less space.
• Its circling time is more than that of SRAM.

in short

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