Done By: Bashayer Al- Suroor ID: 200800649 Flash Memory Done By: Bashayer Al- Suroor ID: 200800649

Outline: Introduction to How Flash Memory Works A sample list of USB devices USB Interface Flash Memory: Tunneling and Erasing How simple is the flash memory Removable Flash Memory Cards What is moseft and how its related to USB What type of technology does USB work with Advantages and disadvantages what to do if you don’t have enough USB port? Conclusion Advice about this devise Sources

Introduction : Flash memory is used for easy and fast information storage in computers. It is used more like a hard drive than as RAM. In fact, flash memory is known as a solid state storage device, meaning there are no moving parts -- everything is electronic instead of mechanical.

Sample lists : Here are a few examples of flash memory: Your computer's BIOS chip CompactFlash (most often found in digital cameras) Smart Media (most often found in digital cameras) Memory Stick (most often found in digital cameras) PCMCIA Type I and Type II memory cards (used as solid-state disks in laptops) Memory cards for video game consoles

Sample list * Printers * Scanners * Mice * Keyboards * Joysticks * Digital cameras * Webcams * Speakers * External hard drives

USB Interface USB flash drive : plugged into a computer. connects into a USB port “tower” can easily be removed without damaging the device. As a sign of the growing popularity of USB flash drives both desktop and laptop computers have numerous USB ports built into the hardware. The actual metal conductor that makes up the USB interface is usually attached to a sliding bar that makes the USB flash drive fit in your pocket better not all models have this feature.

Flash memory is a type of EEPROM chip, which stands for Electronically Erasable Programmable Read Only Memory. It has a grid of columns and rows with a cell that has two transistors at each intersection

Tunneling and Erasing Tunneling is used to alter the placement of electrons in the floating gate. An electrical charge, usually 10 to 13 volts, is applied to the floating gate. The charge comes from the column, or bitline, enters the floating gate and drains to a ground.

Removable Flash Memory Cards There are a few reasons to use flash memory instead of a hard disk: It has no moving parts, so it's noiseless. It allows faster access. It's smaller in size and lighter. So why don't we just use flash memory for everything? Because the cost per megabyte for a hard disk is drastically cheaper, and the capacity is substantially more.

Removable Flash Memory Cards The solid-state floppy-disk card (SSFDC), better known as SmartMedia, was originally developed by Toshiba. SmartMedia cards are available in capacities ranging from 2 MB to 128 MB. The card itself is quite small, approximately 45 mm long, 37 mm wide and less than 1 mm thick.  As shown below, SmartMedia cards are extremely simple. A plane electrode is connected to the flash-memory chip by bonding wires. The flash-memory chip, plane electrode and bonding wires are embedded in a resin using a technique called over-molded thin package (OMTP). This allows everything to be integrated into a single package without the need for soldering

MOSFET MOSFET, or Metal-Oxide-Semiconductor Field-Effect Transistor, is a small device that is capable of both amplifying and switching an electronic signal. A MOSFET involves a metal “gate” that can generate a conducting channel between the two other contacts when a current is applied to it MOSFETs are capable of handling 2000 watts of electricity and are used in almost all analog and digital circuits. important in USB flash drives : they use a very similar type of technology called a floating-gate transistor.

Floating-gate Transistor very similar to MOSFET technology but instead of one gate, it has two. The top gate is called the control gate while the bottom is called the floating gate. completely insulated with an oxide layer. Each memory cell of a USB flash drive is a floating-gate transistor. When an electron is attached to the floating gate, it is trapped within the oxide layer and causes a difference in the voltage of the control gate. When this is measured as a whole, each memory cell makes up a 1 or 0 in binary code, depending on whether it is storing an electron or not.

Advatages The main advantage of USB flash drives is that they are extremely small and can fit in a pocket. USB flash drives do not contain any moving parts, unlike hard drives, which make them very durable and long-lasting. As technology has improved over recent years USB flash drives have steadily increased their storage capacities while decreasing their price. USB flash drives also do not require any software to be installed in order for them to work with a computer as all computers that have a USB port have already been programmed to recognize a USB flash drive. simplicity: even your grannie can plug and unplug her webcam without studying for a PhD in computer science.

you can't put them in the wrong way round and cause any damage you can't put them in the wrong way round and cause any damage. Unlike old-style connectors, they don't have lots of fragile pins to get bent up and damaged each time you take them in and out. They're very robust—so you can plug and unplug them zillions of times.

Disadvantages USB flash drives are far superior to other means of data transportation but they do have a few drawbacks. For one, USB flash drives are so small that they are often lost or forgotten. Also, USB flash drives often do not have any write-protection software to keep viruses from infecting the USB flash drive. Even these minor problems, however, have been met and challenged in many recent models of USB flash drives.

If you don't have enough USB ports on your computer to accommodate all of your devices: Then you can buy a USB hub. Hubs can be powered or unpowered. Hubs can be part of the device such as a keyboard or monitor with USB connections on it. The USB standard allows for devices to draw their power from their USB connection. A high power device like a printer will have its own power supply, but low power devices like mice and cameras can get their power from USB bus so you don't need external power. Individual USB cables can run as long as 5 meters.

USB port USB hub

<<Advice>> conclusion <<Advice>> There is one thing to careful about: USB sockets on computers are soldered directly to the computer's main circuit board (often quite weakly) and if you press them too hard you can break the connections, which stops them from working. Be slow and gentle when you're taking plugs in and out. Don't push them in hard or yank them back out again.

Sources http://www.explainthatstuff.com/usb.html   http://www.tech-faq.com/how-a-usb-flash-drive-works.html