How They Work: “How the Flash Memory Works”

A flash drive is a small storage device that can be used to transport files from one computer to another. They are more or less like keys or thumbs, yet many of these devices can carry all your homework for an entire year! You can keep one on a key chain, carry it around your neck, or attach it to your book bag. A flash drive is easy to use. Once you have created a paper or other work, simply plug your flash drive into a USB port. The USB port will appear on the back of a desktop computer’s PC tower or on the side of a laptop. Most computers are set up to give an audible notice such as a chime when a new device is plugged in. This is normal. The Flash Disk uses the “Flash Memory” Technology; after all, what is this phenomenon? Flash Memory is widely used in many aspects of our lives, more so in most modern consumer electronics like computers, cameras, mobile phones, etc. We store and transfer all kinds of files from digital cameras, music files, word processing documents, PDFs and many other forms of media. Many times, the computer’s hard drive is not exactly where you want your information. Whether you want to make backup copies of files that live off your systems or if you worry about your security, portable storage devices that use a type of electronic memory called flash memory may be the handy solution. Electronic memory comes in a variety of forms to serve a variety of purposes.Flash memory is used for easy and fast information storage in computers, digital cameras and home video game consoles. 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; they employ logical electronics known as semiconductors, everything is electronic instead of mechanical. There are several applications of flash memory, these include among others; the computer’s BIOS (basic input output system) 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, etc. Flash memory is a type of EEPROM (Electronically Erasable Programmable Read Only Memory) chip. It has a grid of columns and rows with a cell that has two transistors at each intersection. The two transistors are separated from each other by a thin oxide layer. One of the transistors is known as a floating gate, and the other one is the control gate. The floating gate’s only link to the row, or word line, is through the control gate. As long as this link is in place, the cell has a value of 1. To change the value to a 0 requires a curious process called Fowler-Nordheim tunnelling. Tunnelling 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. This charge causes the floating-gate transistor to act like an electron gun. The excited electrons are pushed through and trapped on other side of the thin oxide layer, giving it a negative charge. These negatively charged electrons act as a barrier between the control gate and the floating gate. A special device called a cell sensor monitors the level of the charge passing through the floating gate. If the flow through the gate is above the 50 percent threshold, it has a value of 1. When the charge passing through drops below the 50-percent threshold, the value changes to 0. A blank EEPROM has all of the gates fully open, giving each cell a value of 1. (To be cont’d eddie@afrowebs.com