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White Paper: Facts about Flash

The growth in the market for portable computing devices has led to high demand for small size storage. Flash memory is ideal for this

Contrary to what its name may imply, Flash memory is here to stay. Since its inception almost 15 years ago, Flash memory has evolved into a versatile and practical storage solution. Recently, new applications and rapidly increasing demand for Flash have brought this adaptable, yet advanced technology to the front door of many business applications.

Flash memory is a solid-state, non-volatile, rewritable memory that works like RAM and is hard-disk drive combined. Flash memory stores bits of electronic data in memory cells, just like DRAM and SRAM, but Flash also works like a hard-disk drive because when the power is turned off, the data stays in memory. Flash memory is becoming increasingly popular for portable computing and communications applications. Here are a few reasons why:

Nonvolatile storage - retains data even with the power off (much like a disk drive)

Low voltage - consumes very little power and saves battery life

Durability - able to withstand severe shock or vibration without losing data

Compact size - suitable for a broad range of portable electronics speed - extremely fast access time

Flash memory and RAM look very much the same. Both can come in the form of discrete chips, modules, or memory cards. They store information in the same way, but Flash memory doesn't need to be constantly refreshed like DRAM, and it doesn't need constant power to retain data like SRAM. Flash memory is non-volatile, which means that it retains its data even when the power is turned off.

The question is sometimes raised: "If Flash works like RAM but it doesn't need power to retain data, why not use Flash to replace main memory in computers?"

There are several reasons why this can't be done. First of all, the memory cells in a Flash chip have a limited lifespan of 100,000 write cycles. Also, because of its design, Flash memory must be erased in blocks of data rather than single bytes like RAM. (That's like having to erase the entire word every time you press the "delete" key, instead of erasing a single letter.) Beyond that, Flash memory is too expensive to compete with RAM for main memory.

Nevertheless, while it bears some similarity to RAM, Flash memory has been carving out its own independent markets, with little direct competition to RAM. Some examples include:

Discrete Flash chips used in desktop PCs to store system configuration information

Flash modules used in networking equipment to store microcode and instructions

Flash memory cards used in portable computers and palmtops for mass storage

Magnetic disk drives have moving parts and thus a lower tolerance for shock, vibration, extreme temperatures, or harsh environments. Electronic "Flash drives" have no moving parts to draw excess current, so they consume less energy yet are smaller and faster than hard-disk drives. Flash memory can also withstand shocks up to 2000G's without losing data. That's roughly equivalent to a 10ft drop onto concrete. Also, with no physical surface like on a standard hard drive platter to grab data from, data access time is significantly decreased.

Again, the question is sometimes raised, "If Flash is faster and smaller than a hard-disk drive, why not use Flash memory to replace all hard drives?".

The reason is that in practical applications, Flash memory and hard-disk drives serve different purposes. For example, typical desktop PCs need gigabytes of storage space (far beyond the present capacity of Flash memory - about 100Mb). Also, desktops don't have power constraints because they're plugged into A/C outlets, and durability isn't an issue because they're stationary. In this case, there's no need for the features that Flash has to offer. Plus, as with RAM, Flash cannot compete with hard disks in price.

However, a Flash drive would be more suitable than a hard-disk drive in situations where size, power consumption, and ruggedness are important factors, and where capacity needs are smaller. Some examples would include handheld computer games, digital cameras, palmtop computers in manufacturing environments, or notebook computers in medical, insurance claims, and military/government field situations.

Because of its ability to withstand tremendous shock without losing data, its ability to store information without constant power, and its low voltage requirements, Flash memory is a suitable replacement for portable hard drives in rugged situations, yet its range of applications is also broader. Some other applications for Flash memory include: digital cameras, cell phones, pagers and audio recorders, scanners - to store images and voice data networking devices; to store the microcode and instructions needed for transferring data printers and print servers; to hold fonts or frequently-used graphics desktops; and to replace ROM BIOS chips (the BIOS configures your computer every time you turn it on).

One ideal application for Flash memory would be in a digital camera, like the KODAK Digital Science DC40 or DC50 Zoom camera. In this camera, Kingston's 20Mb Type II Flash (DP-ATA/20) card would function as an electronic "roll" of digital film. In fact, depending on data compression, an average of 6 to 15 pictures per Mb could be stored in this Flash card. After taking pictures in the field (e.g. police, insurance adjusters, architects), the digital images could be loaded directly into any notebook or desktop. Another instance might be in a truck that uses an on-board computer. Every time the truck hits a pothole in the road, the system could crash, but not with Flash memory.

While Flash memory is in no position to compete with RAM or disk-drives in functionality, price, and capacity, it brings distinct advantages and opportunities for various business applications. With an increasing number of applications, Flash memory growth is expanding.

At present, Flash memory is one of the fastest growing segments of the semiconductor industry. As prices drop and capacities increase, Flash memory will probably continue to grow in the PC Card market with the greatest growth in digital recording and wireless communications.

Compiled by Ajith Ram

(c) 1999, Kingston Technology Company


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This was first published in January 1999

 

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