The flash drives are an important part in the lives of many people today as they represent the easiest way to store and carry with us the documents or information we need. Despite being a necessity, many people are unaware of their meaning, the way they work and what they are for.
The flash memory is a device that is going to allow storage of large amounts of information and data in a small space, making possible reading and writing through a series of electrical impulses .
- Flash memory features
- What is flash memory for?
- How does it work
- Advantages of flash memory
Flash memory is a memory chip which is used to store and transfer data between a personal computer and a number of different digital devices . This type of memory has the ability to be reprogrammed and erased electronically. So usually we can be found in units USB flash , players MP3, digital cameras and solid – state drives.
Flash memory is a type of memory that only allows electronically erasable and programmable reading , which is known by its acronym as EEPROM , although it can also function as an independent memory storage device , in other words as a USB drive . EEPROM is a type of data memory device that uses an electronic device to erase or write data that is digital. Flash memory is a different type of EEPROM, which is programmed and erased in large blocks . This type of flash memory incorporates the use of transistors of floating gate to fulfill the function of storing data.
Flash memory features
The main characteristics of flash memory are the following:
- This type of memory is based on the use of semiconductors .
- It is not rewritable .
- The information stored in them is not erased when the device is disconnected.
- They can be connected to computers or other devices .
- They are easy to handle and transport .
- They consume less energy and are cheaper .
- They are very resistant to shocks.
- They do not contain moving parts or mechanical actuators.
- They have thermal resistance .
What is flash memory for?
Flash memory used to store the information in a semiconducting type NAND flash memory. They are capable of maintaining their contents without the need to supply electrical energy . They can keep the information without altering it for up to 10 years, and have the capacity to be rewritten between 10,000 to a million times.
The main uses of USB flash memory read or save information such as images , music data , photographs and then connect it to other devices for the proper reproduction or display of the information.
Flash memory was first introduced in 1980 and was developed by Dr. Fujio Masuoka , Toshiba inventor and factory manager . Flash memory got its name due to its ability to erase a block of data quickly. Dr. Masuoka’s goal was to create a memory chip that would retain data when powered off.
In 1994 and 1998, the main memories that we know today were born and the technology soon raised its use in different applications in other fields. In 1994 SanDisk began to market memory cards based on these circuits, and since then, the evolution came through small low-power devices such as portable MP3 players, memory cards for video consoles, storage capacity for PC Cards that they allow us to connect to wireless networks and many more.
How does it work
Flash memory may provide memory of high density because it requires only a few components for each memory cell. The structure of the memory cell is very similar to the EPROM . Each flash memory cell consists of the basic channel with its source and the drain electrons that are separated by the channel. Above the channel in the Flash memory cell is a floating gate that is separated from the channel by an extremely thin oxide layer.
The quality of this layer is crucial for reliable memory performance. Above the floating door is the control door . This is used to load the gate capacitance during the write cycle .
The flash memory cell works by storing charge in the floating gate . The programming of the flash memory cell involves a process known as injection of hot electrons . When programming the control gate is connected to a ” programming voltage “ . The drain will have a voltage of approximately half this value while the source is grounded. The voltage at the control gate is coupled to the floating gate through the dielectric , raising the floating gate to the programming voltageand reversing the channel underneath. This results in the channel electrons having a higher drift velocity and higher kinetic energy .
The types of flash memory that exist are:
- CompactFlash (CF Card)
- XD Picture Card
- Sony Memory Stick (MS)
- Secure Digital (SD) and Multimedia Card (MMC)
- IBM Microdrive
The average data transfer rate in a flash memory can be of two types generally:
- 10 MB / second for reading (about 66x, considering that 1x equals about 150 KB / sec.)
- 5MB / sec (about 33x, considering that 1x equals about 150KB / sec), about half write.
Advantages of flash memory
One of its main advantages is portability , as it can be taken anywhere we go. Its size is small so it is easy to carry. An impressive number of files and applications can be placed in it . It does not need electricity to function, it has no moving parts and it is more durable than other types of memory. The information is also very easy to delete and adding files works the same way.
Like all devices also it has its disadvantages, such as the limitations of writing and price . There is a finite number of times you can erase the information , which is about 100,000 times.