The flash storage market has evolved rapidly over the past 3 decades. As each new generation of storage form factor and memory technology arrives, new acronyms and terms are created.

To make sense of this, Cactus is providing the flash storage glossary below which covers and provides definitions of many of the key terms in the flash storage market today. In addition to the terms, helpful links to more information are available.

If you would like to see additional items defined, please let us know.


3D (3 Dimensional) NAND is the latest process to pack more memory in a NAND component. It stacks the NAND cells vertically in the silicon itself creating up to 64 levels of bits.

AES256 Encryption

AES256 encryption is an encryption algorithm which is popular in SSDs today. If a fast data erasure is needed, removing the key needed to decrypt data makes the information stored on the SSD unintelligible.

ATA Interface

The ATA interface (aka IDE interface) was created for hard disk drives over 20 years ago and was adopted to provide a common interface for some flash storage devices such as CompactFlash, PC Cards, IDE SSD and IDE Disk-On-Module. It has a data and address bus which requires 40+ pins to implement.

Cactus' products support IDE interface


Also known as BOM, this is the list of components that go into the manufacture of an electronic device. A locked-BOM device is one that does not change components.


CFast is a form factor which is defined by the CompactFlash Association as a faster version of the CompactFlash form factor. It uses a SATA interface versus the CompactFlash's ATA interface.


CompactFlash (aka CF) is a form factor which is defined by the CompactFlash Association which is based on the ATA interface. It was originally launched in 1995 and its smaller size really helped the Digital Imaging market to blossom. It is a very popular form factor for embedded industrial designs.

Conformal Coating

Conformal Coating for a SSD refers to applying a acrylic or other coating to cover the circuit board and components so there are less susceptible to shorting or damage from dust, moisture and other outside contaminants. Cactus can conformal coat all of our product offerings.

Consumer Grade Flash

Consumer Grade flash storage is the lowest cost flash memory solution available. They come in many forms from SSD to SD and microSD cards. Their disadvantage is they are typically built using TLC NAND in either planar or 3D architecture which has extremely low endurance and no BOM control.

COTS (Commercial Off-The-Shelf)

Commercial Off-The-Shelf (COTS) devices signify a commercial system component (such as a SSD) which is available in the market as a standard product and is not a military only device.

CSfC (Commercial Solutions for Classified)

Commercial Solutions for Classified is a program within the National Security Agency to provide system architectures using COTS (Commercial Off-The-Shelf) products to meet high levels of security for classified data in government and commercial systems.

DAR (Data At Rest)

Refers to data stored on a SSD when powered off. Typically related to the need for encryption to protect classified data from access by unauthorized users when SSD is not in use.

Data Retention

Data Retention of flash memory refers to how long a NAND cell can retain the data stored in it. The older memory devices had a 10 year data retention, but the latest TLC and 3D NAND are challenged to reach similar levels.

FDE (Full Disk Encryption)

Full Disk Encryption (FDE) refers to encrypting the entire SSD including the Operating System (OS) as opposed to File Encryption (FE) which is only performed on a file by file basis.

FE (File Encryption)

File Encryption (FE) refers to encrypting a file or group of files on a SSD. Only properly authenticated users can access these files.

Flash Endurance

NAND flash memory blocks have a finite number of times they can be erased (written) which is called endurance. SLC NAND has the most endurance cycles, with MLC having 20-30 times less and TLC having 200-300 times less.

HWFDE (Hardware Full Disk Encryption)

Hardware Full Disk Encryption (HWFDE) is typically implemented by use a SSD with a hardware encryption module or engine which provides protection to the Data At Rest (DAR) when the SSD if powered off.


An IDE SSD is a Solid State Drive with a IDE (aka Parallel ATA) interface. They come in 2.5" form factors, but similar IDE interface flash storage come in CF, PC Card and IDE DOM form factors.

Industrial Grade Flash

Industrial Grade Flash Storage signifies a flash storage device, like CompactFlash, SSD, SD Card, which is built using Single Level Cell NAND flash memory and has a robust controller technology. The better vendors of Industrial Grade Flash storage also lock the Bill-Of-Material (BOM) for many years - meaning there are no changes to components used to build the product.

Industrial MLC Flash

Industrial MLC flash storage devices are made with MLC NAND and meant for OEM designs which do not require high endurance or duty cycles. A locked-BOM for a life cycle of 3 - 5 years ensures an OEM can purchase the same part over the production cycle.

Industrial pSLC Flash

Industrial pSLC flash storage from Cactus Technologies signifies our products based on pSLC NAND. These parts are much more reliable, with 6 times the endurance of Industrial MLC products based on MLC NAND. Even with this added reliability, for mission critical applications, there is no substitute for Industrial Grade based on SLC NAND.

Life Cycle

Life Cycle is how long a given locked-BOM SSD product is available in the market. A locked-BOM means there are no components changes and long life cycle at Cactus refers to >5-7+ years for Industrial Grade and 3-5+ years for our Industrial pSLC and Industrial MLC products.


Locked Bill-Of-Material signifies no components which are used to manufacture a flash storage device change without notification to the customer. A locked-BOM is tied to a specific part number. If you order that part number it is build identically to previous ones.


M.2 (previously called NGFF for Next Generation Form Factor) is a small form factor flash storage device which comes in multiple physical dimensions and can support either a SATA or PCIe electrical interface. It is most popular in consumer devices, but has recently starting seeing use in embedded OEM applications.

See Cactus' M.2 Industrial pSLC Products

Military Erasure Features

Military Erasure Feature sets are available as an option on some SSD products. They allow erasure via different defined erasure routines to meet the requirements of multiple military and government agencies. Typically these routines require different data patterns to be written in sequence over the entire flash memory space.


Multi Level Cell (MLC) NAND contains 2 bits per cell. It was created to double the capacity of a SLC NAND cell which only stores 1 bit per cell. It does this by varying the voltage level within the cell to one of 4 states which represent 00, 01, 10 & 11. MLC NAND components are used in Cactus Industrial MLC products.


mSATA (aka mini SATA) is a small form factor flash storage device which has a card edge connection that mates to the host system's connector. It is popular for embedded systems.

NIAP (National Information Assurance Partnership)

The National Information Assurance Partnership (NIAP) is a NSA program to validate and certify COTS components for use in a Commercial Solutions for Classified (CSfC) Capability Packages (CP).

PATA Interface

The PATA (Parallel ATA) interface is similar to the original ATA/IDE interface and used for a common interface on several flash storage devices such as CompactFlash, PC Cards, IDE SSD and IDE Disk-On-Module.

PC Card

The PC Card is one of the oldest flash storage form factors still being shipped in the market. It has a 68 pin connector to support the IDE/ATA interface and is enclosed in a rugged metal lid set.

PCIe Interface

The PCIe interface is an extremely high performance flash interface which is used in high end enterprise computing applications. Along with the high performance, comes high power requirements which tends to make other interfaces more suited for embedded applications.


PCMCIA (Personal Computer Memory Card Industry Association) was the original name of the industry standards body for what is now the PC Card form factor.

Planar NAND

Planar NAND used to just be NAND flash until 3D NAND which stacks bits vertically came out. Once 3D NAND was created, all previous NAND is now referred to as Planar (aka flat).


Pseudo Multi Level Cell NAND memory. A NAND cell, such as TLC (Tri Level Cell) which is capable of storing 3 bits per cell, used to store a 2 bits per cell. This provides better endurance & data retention, although less capacity, than the underlying TLC NAND. This is a newer technology and meant to make improve the extremely poor TLC endurance and data retention.

Product Change Notification

A Product Change Notification (PCN) goes hand in hand with a locked-BOM and long life cycle for flash memory devices. The PCN is the method to notify customers when there is a change coming in the BOM (how the part is made) of a SSD and allows them time to sample, test or make arrangements to extend the life of the current BOM configuration.


Pseudo Single Level Cell NAND memory. A NAND cell, such as MLC (Multi Level Cell) which is capable of storing multiple bits per cell, used to store a single bit per cell. Only the high and low states are used which provides better endurance & data retention, although less capacity, than the underlying MLC NAND. Cactus Industrial pSLC products use MLC NAND in the pSLC NAND mode.


Pseudo Single Level Cell (pSLC) NAND memory. A NAND cell, such as MLC (Multi Level Cell) which is capable of storing multiple bits per cell, used to store a single bit per cell.

SATA Interface

The SATA (Serial ATA) interface was created initially for higher performance hard disk drives. It was adopted by the flash storage vendors to create higher capacity and performance SSD. SATA currently has 3 different performance levels which are backward compatible - SATA I up to 1.5Gbits/s; SATA II up to 3.0Gbits/s & SATA III up to 6.0Gbits/s.


A SATA SSD is a Solid State Drive with a Serial ATA interface. This most popular version of this is the 2.5" SATA SSD, but other SATA devices are mSATA, Slim SATA and CFast.

SD Interface

The SD interface was created in the early 2000s time frame and has a serial interface for simple OEM host system designs. It can be quite fast and allows scaling to multiple data lines or can be as simple as a single SPI transfer.


The SDChip is a small form factor, BGA package, SD interface flash module which allows OEMs to eliminate the connector of the SD & microSD cards from their embedded designs. It comes in the Industrial Grade offering from Cactus Technologies.

SLC Lite

SLC Lite is a marketing term for pSLC flash storage products used by some flash storage manufacturers. Cactus Industrial pSLC uses pSLC. See pSLC NAND for more details.


Single Level Cell (SLC) NAND is the oldest and highest reliability NAND flash in the market due to storage of only a single bit of data in a cell. Larger SLC NAND cell sizes such as 43nm and 32nm are the most reliable in the market and have best endurance, data retention and operating temperature. Cactus Industrial Grade products use only SLC NAND.


Slim SATA is a form factor which has the same connector as a full size 2.5" SATA SSD, but is only a shorten circuit board module. It is not a very popular form factor.

SMART Attributes

SMART attributes are the data which is reported back from the SSD when the SMART (Self Monitoring Analysis & Reporting Technology) command is issued. The data can be used to analyze the remaining life of the SSD and is ideal for performing accelerated life testing of a product.


SSD stands or Solid State Drive and can be any device which is made without moving parts. It could be DRAM based, but almost all SSD today are based on flash memory. The most popular SSD are 2.5" SATA SSD, but they come in many form factors such as mSATA, CF, SD & USB Flash Drives.


SuperMLC is a marketing term for pSLC flash storage products used by some flash storage manufacturers. Cactus Industrial pSLC uses pSLC. See pSLC NAND for more details.

SWFDE (Software Full Disk Encryption)

Software Full Disk Encryption (SWFDE) is a method to provide full disk encryption to a SSD which provides a solution to protect classified Data At Rest (DAR) in a powered off SSD.


TLC (Tri Level Cell) NAND is a NAND flash which stores 3 bits per cell. While it stores data very densely, to reach high capacities, it is not the most reliable of the memory technologies. Typical TLC NAND endurance is as low as 300 write cycles per physical block and is focused mainly on consumer applications.

USB Disk-On-Module

A USB Disk-On-Module is a small form factor circuit board with a USB interface and a 10-pin connector. The connector can be a low profile 2mm version or larger 2.54mm. It is known in the industry under several names which include uDOM, uDiskOnChip & uDOC to name a few.

USB Flash Drive

A USB Flash Drive is a small form factor removable flash storage device with a USB interface. It is commonly used as a backup from a notebook or personal computer. In the Industrial world, there is a trend toward using more reliable USB flash drives, such as Industrial Grade to ensure factory programming does not get corrupted. Commonly called Thumb Drive, Jump Drive, Pen Drive and Flash Key.

Write Abort

Write Abort is a failure caused when power is unexpectedly lost during a write to the NAND flash of a flash storage device. The more industrial a flash storage device is - the less susceptible it is to a write abort situation. The more consumer focused devices have difficulty with unexpected power loss and will crash if experiencing too many of these occurrences.

Write Protect

A Write Protect option on a SSD allows the user, via a physical switch, command or both to disable writes to the flash storage device. This can be used if there is a need to protect original or recently generated information from becoming overwritten.