Tag Archives: Memory

Replacement for Flash Memory

Today flash memories or thumb drives are commonly used as devices that store information even without power—nonvolatile memory. However, physicists and researchers are of the opinion that flash memory is nearing the end of its size and performance limits. Therefore, the computer industry is in search of a replacement for flash memory. For instance, the National Institute of Technology (NIST) conducted research is suggesting resistive random access memory (RRAM) as a worthy successor for the next generation of nonvolatile computer memory.

RRAM has several advantages over flash. Potentially faster and less energy hungry than flash, it is also able to pack in far more information within a given space. This is because its switches are tiny enough to store a terabyte within a space the size of a postage stamp. So far, technical hurdles have been preventing RRAM from being broadly commercialized.

One such hurdle physicists and researchers are facing is the RRAM variability. To be a practical memory, a switch needs to have two distinct states—representing a digital one or zero, and a predictable way of flipping from one state to the other. Conventional memory switches behave reliably when they receive an electrical pulse and switch states predictably. However, RRAM switches are still not so reliable, and their behavior is unpredictable.

Inside a RRAM switch, an electrical pulse flips it on or off by moving oxygen atoms around, thereby creating or breaking a conductive path through an insulating oxide. When the pulses are short and energetic, they are more effective in moving ions by the right amount for creating distinct on/off states. This potentially minimizes the longstanding problem of overlapping states largely keeping the RRAM in the R&D stage.

According to a guest researcher at NIST, David Nminibapiel, RRAMs are as yet highly unpredictable. The amount of energy required to flip a switch may not be adequate to do the same the next time around. Applying too much energy may cause it to overshoot, and may worsen the variability problem. In addition, even with a successful flip, the two states could overlap, and that makes it unclear whether the switch is actually storing a zero or a one.

Although this randomness takes away from the advantages of the technology, the researcher team at NIST has discovered a potential solution. They have found the energy delivered to the switch may be controlled with several short pulses rather than using one long pulse.

Typically, conventional memory chips work with relatively strong pulses lasting about a nanosecond. However, the NIST team found less energetic pulses of about 100 picoseconds, which were only a tenth of the conventional pulses, worked better with RRAM.  Sending a few of these gentler signals, the team noticed, was more useful not only for flipping the RRAM switches predictably, but also for exploring the behavior of the switches.

That led the team to conclude these shorter signals reduce the variability. Although the issue does not go away totally, but tapping the switch several times with the lighter pulses makes the switch flip gradually, while allowing checking to verify whether the switch did flip successfully.

Adding Memory to the Raspberry Pi

Although the memory onboard the Single Board Computer Raspberry Pi or RBPi is sufficient for most applications, some may feel the necessity of expanding the storage capacity. The options provided on the RBPi are limited, as the USB ports often engage a keyboard, a mouse or a game controller and the SD card slot holds only a single device.

The most obvious option for expanding the storage capacity on the RBPi is through the USB ports. However, tying up ports with a USB hard disk drive or flash drive can run into difficulty if you need the port for plugging in another USB device. One way of getting around this problem is by using powered USB hubs. It is important to realize the RBPi cannot supply enough power for driving the hub.

Using a powered USB hub makes it easy to add USB devices to your RBPi, including additional storage. However, you must consider a few things when expanding storage on your RBPi. In reality, there are only two common USB storage options available – flash drive and hard disk drive. Nevertheless, you may also consider a card-expanding trick for the Raspbian operating system for your RBPi. These are the three primary options available for expanding storage on your SBC. Apart from this, you may also consider using secondary storage devices such as networked drives, USB DVD-r drives and NAS drives.

The SD card in the RBPi acts as the main storage option – use an SDHC card for best results. It is a boot device acting as the general storage and from which the operating system also runs. You may think of the SD card as a replacement for the HDD of a regular desktop computer, more like an SSD or Solid State Drive, as it has no moving parts and uses very low energy.

By default, Raspbian, the standard Operating System of the RBPi, is designed to run from a 2 GB SD card. Therefore, when you flash the Raspbian image, the SD card will have a partition of 2 GB, with the balance of the card memory remaining unused.

To get around this, you must use the expand file system feature included in the raspi-config screen in Raspbian. This enables expanding the size of the partition to the maximum capacity of the SD card.

When you insert your flash drive into a USB port of the RBPi, you may be surprised it does not have the same effect as it does in a regular Ubuntu or Windows computer. It is not enough to insert the flash drive, Raspbian expects you to mount the device manually before you can use it as an additional USB storage device. However, before you can mount it, you must know the exact device name that Raspbian has assigned to the drive.

For this, the command necessary is: sudo ls /dev/sd*. The command “sudo” gives you temporary administrative status, “ls” allows listing the devices and “/dev/sd*” lists the devices seen by Raspbian. With this command, you will know the number Raspbian has assigned for your drive.

Now, you can mount the USB flash drive and use it as an additional storage device with the command: sudo mount -t vfat /dev/[USB DEVICE NUMBER] /mnt/usb.

What’s the difference between SD vs SDHC cards?

We use several types of digital devices, which store data on external memory cards. Unfortunately, just as there is a large variety of digital devices, there is a plethora of memory cards to add to the confusion. People juggle with SDHC, SDXC, SD, MiniSD and MicroSD among the most popular cards. Often it is puzzling to ascertain what type of memory card will suit your camera, phone, MP3 player, tablet or other mobile digital device. Most memory cards are flash type with difference in formats, sizes and speeds.


Apart from Apple products, most digital devices offer means of adding to the internal storage capacity. Typically, this is some variety of the Secure Digital or SD memory card. Although SD has emerged as the most popular flash memory format, there are scores of SD cards of all shapes, sized and speeds to choose from – making it somewhat confusing to pick the right one for your device.

With flash memory cards, the primary aspects that need consideration are their physical format, size and speed. Since each of these variables has its own set of classes, you may find anything from 1GB Class 2 MicroSD card to a 16GB UHS-1 SDXC card.

When buying a memory card, consider where you are likely to use it. Chances are that your camera, smartphone and your camcorder use different sizes of card. Although you can start with the smallest physical format and use adapters to make it fit in different gadgets, it is better to use the card size that is intended for the device.

The largest format is the standard SD card measuring 32x24x2.1mm. Most digital cameras use this format, with high-end cameras shifting to CompactFlash cards, which are smaller. These days, the least frequently used card is the MiniSD card, measuring 21.5x20x1.4mm. Almost all cell phones and smartphones nowadays use the MicroSD card, which has dimensions of 15x11x1mm.

Memory cards come in a huge variety of storage capacities. However, the maximum capacity of a standard SD card is limited to 2GB. The most popular MicroSDHC or Micro Secure Digital High Capacity cards are available with capacities between four and 32GB. The Secure Digital Extended Capacity or SDXC can theoretically range from 64GB to 2TB. However, currently, the largest capacity available is only 128GB.

Larger the memory capacity, so much more you can store. However, if you have an older device, chances are that it can use only the larger SD card. The classification SD/SDHC/SDXC applies to devices as well. Therefore, double-check the type of cards your device can handle. SDHC cards will not work in a device that can handle only an SD card.

Flash cards are available in various speeds as well. The speed class ranges from Class 2 (slowest) to Class 10 (fastest). Class 2 is useful for standard-definition video recording. With Class 4 to Class 6, you can record high-definition video. When you are recording HD video or consecutive recording, Class 10 is more suitable.

If your camera or smartphone can shoot HD video or if you are going to shoot many high-resolution photos in quick succession, you should buy the Class 10 card. For occasional snapshots or casual videos, Class 4 to Class 6 cards will do fine. Prices vary between different types of cards – high-speed high-capacity cards are more expensive.

Magneto resistive random access technology (MRAM) for better memory storage

Technologists researching at the laboratories of the National University of Singapore in the department of Electrical and Computer Engineering have developed a new technology that will help in enhancing storing information in electronic systems in a better and more durable manner. Called Magneto Resistive Random Access Technology, this innovative method increases the storage space considerably and ensures that all fresh data will remain intact, even when there is a power failure. The team of researchers, led by Dr. Yang Hyunsoo, has filed for a provisional patent in the USA. They claim that the development will bring about a structure that will be of use to MRAM chips of the next generation.

This innovative method of storing information has a very wide field of application. All devices in the field of electronics such as Personal computers, laptops, mobile phones and all mobile devices will benefit from this unique technology. Data storage is required in various fields of activity such as in transportation, avionics, military, robotics, industrial motor controls, management of energy and power. Another major user is electronic equipment for health care.

According to Dr. Yang, the new technology will increase storage space, and enhance the memory. According to him, computers, laptops, etc., do not need booting up and there is no necessity for using the “Save” key regularly. Fresh data is not deleted even when there is a stoppage of power, unlike the current DRAMs in use. What is of greater significance is the memory will last for a minimum of 20 years and maybe for an even longer period. Compare this to the present method of storing information, which gives the user only about a year of stored data. One of the best uses is in the case of mobile phones. According to Dr. Yang, “we usually need to charge them daily. Using our new technology we may need to charge them on a weekly basis.” This will be a substantial cost-saver.

MRAM, the new technology, enables data to be retrieved even if the equipment concerned is not powered up. Additionally, MRAM consumes low power and has high bit density. The new technology is expected to bring about a sea of changes in computer architecture. Manufacturers will find it easier to use MRAM as flash memory can be dispensed with. That will also help in bringing down the cost substantially. The success of MRAM has induced major semiconductor manufacturers like Intel, IBM, Samsung and Toshiba to conduct further research.

Currently, MRAM uses technology based on current induced magnetization in a horizontal plane. It requires ultra-thin ferromagnetic structures, less than 1 nanometer, which are difficult to manufacture, has low reliability and the retention period is less than a year. The NUS team collaborating with Saudi Arabia’s King Abdullah University of Science and Technology has developed a multi-layer magnetic structure of 20-nanometer thickness. It effectively provides a film structure that helps in the storage of information and data for at least 20 years. The team is looking for collaboration with the industry.