Now I know my three-bit three-dee vee-nand ess-ess-dee [Editorial]
We just put up a press release about our new 3-bit 3D V-NAND SSD for all consumers. But we bet many of you were thinking: 3-bit? 3D? V-NAND? What in the world does all that mean? So, here we provide you with a bit more information. Hope this helps.
‘Bit’ is the smallest, basic unit of information in computing – the digital, binary 0 or 1. Eight(8) bits make up a byte, ‘about’ a thousand (210=1024 to be exact*) bytes make a kilobyte, ‘about’ a million (again, 220=1048576 to be exact*) make a megabyte and so on.
Now, flash memory chips have ‘cells’ which can contain a bit or multiple bits of information which eventually add up to the full memory capacity. It’s very much like how cells add up to make a tissue or organ.
This new chip we’re talking about contains three bits per cell as opposed to one or two bits per cell, which is why it’s also known as Triple Level Cell or TLC. This means each cell can store 3 bits of data instead of 2-bits/cell chip or one in the single-level cell chip. Theoretically, this means that you can have about 30% (or 33.33333333…% – do the math 😉 less cells to achieve the same memory density, which offers advantages in size and manufacturing efficiency.
What’s the catch? While multi-level cell flash memory has these benefits, there are tradeoffs when it comes to slower write speeds and lower program-erase cycles. But because Samsung has the in-house capability to integrate end to end, we optimized at each step of the design process and component from flash to controller, firmware, and to DRAM. Bringing together the best flash solutions we can offer, advanced signal processing algorithms, middleware and firmware for each component, Samsung was able to bring up the drive’s speeds and endurance up to top-notch.
When you think of memory chips, it’s easy to picture a 2D grid where for more resources you need to place more chips across a certain area. To cram as many cells next to each other is one thing but this would cause data from adjacent cells to interfere with each other. Think small dorm rooms with thin walls. Well, Samsung took this to a whole new dimension, stacking these cell arrays ‘vertically’ in ‘3-Dimension’ and hence, ‘Vertical’ NAND. Through this approach, Samsung’s V-NAND flash memory is able to offer SSD products with higher density onward, overcoming the scaling limit of 2D planar NAND.
Samsung has pioneered the V-NAND product category and has been introducing SSDs equipped with 2-bit V-NAND flash memory. We announced mass production of industry first 3-bit 3D V-NAND flash memory in October, and now we have SSDs that benefit from this engineering feat.
So NAND is a type of flash memory; what does that mean? Flash is an electronic non-volatile memory (meaning the data stays even if you turn the power off. Volatile memories, like RAM, lose the information it was holding once the power goes out). Technical terms aside, it’s basically a chip that’s consisted of many, many cells that store electrical charges (or the lack of it) to show bits (0s and 1s). The collective amount of these cells determines the memory capacity of that particular flash memory chip.
There are two main types of flash – NOR and NAND. It’s going to take a long time to explain the difference (like the structure and characteristics) so we’ll save that for another day. To keep it short, NOR offers faster read speed and random access capabilities but the write and erase speed is slow. NAND, on the other hand, has faster write/erase speeds and smaller memory cell size. This makes the NAND easier to scale, which allows bigger memory capacity. And while read speed of NAND is slower than NOR, it’s still more than good enough to support most consumer applications like video/music/data storage.
So NOR is better for code storage and execution, usually in smaller capacities while NAND is used in many memory solutions such as SSDs, embedded and external memory cards (for smartphones, cameras and gaming devices), memory sticks, and etc.
SSD (Solid State Drive)
SSD is a device that uses memory chips to store data persistently. The easiest way to better understand an SSD would be to compare it to an HDD (Hard Disk Drive). Before SSDs, most, if not all computer storages used Hard Disk Drives.
▲850 EVO SSD
HDDs, like floppy disks, used disks (or ‘platters’) and heads that would move to and fro to access the information stored on these magnetic disks. Though HDD technologies did evolve, offering smaller disks (3.5” > 2.5” > 1.8”), the physical/mechanical aspect did not change much.
SSDs do not have moving components like the disk or head, which is why they called ‘solid state’ drives. Instead, they have memory chips (like NAND flash), a circuit board and controller – all electronic. Because they don’t have mechanical parts, SSDs are typically lighter and quieter, allowing faster access to data and are more resistant to physical or magnetic shock (compared to HDDs) while being more energy-efficient. Also, they can benefit more from advancement in chips, like multi-level cells or vertical stacking technologies, to make them faster and greater in capacity.
For even more information, please refer to our previous announcements from 2014 and the Samsung SSD website:
* The exact number of bytes differs from a thousand or a million because it stacks up in binary.
** This is an editorial by Abraham Pai (Corporate Communications, Samsung Electronics). Views and opinions expressed in this article do not necessarily represent those of Samsung Electronics.
*** Maria Yoon (Global Communications, Device Solutions, Samsung Electronics) contributed to this article.
Corporate Communications, Samsung Electronics
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