Annoyances and Applications of USB devices

Less memory than specified – a certain amount of memory is always taken up by the file allocation table. This is normal for any memory storage device, when the device is formatted first time; a file allocation table for a FAT is created. The FAT stores the locations of each file stored in the drive. The Fat takes very little space on the drive by default .all USB flash memory devices use the FAT32 type of partition.

In addition ,are pre installed with software that allows you to carry sensitive data in an encrypted format and back up data .The preinstalled software on your drive is usually installed in a separate partition .this causes the total available space on the drive to reduce further but not much.

USB is designed such that you can add up to 127 devices to one computer .This is accomplished through the use of hubs .In a effect the hub expands the number of USB ports. The most common hub is a 4-port unit which can be plugged into one of the USB connections on your computer, giving additional 4 USB ports.

The specifications of a USB states that the maximum length of the USB cable is 5 meters so you can not extend it more that 5 meters without using a USB repeater cable .This cable contains active electronics that boost the USB signal for maximum reliability and performance over extended distances. Up to 4 of these USB active extension cables can be linked to extend the distance between your computer and your USB peripheral to up to 80 feet.

But the best solution is a self powered hub with a fixed 10m cable that has a one port bus powered hub in the middle.

Applications

1Mobile phones
2 MP3 Player
3 Medical equipments
4 Digital cameras
5 Digital video cameras
6 GPS navigation systems
7 Other portable devices
8 Personal computers
9 Data communications
10 Testing equipments

Safety While Removing Hardware

If you work with many different USB devices ,You probably use the “Safety Remove Hardware” icon quite a bit .And you supposed to remove carefully a USB device by clicking on the icons in your taskbar and stopping the whole process instead of just unplugging it without any warning so chances of loosing that icons

Whenever you plug in an external memory device to your computer ,an icon pops up on your taskbar that reads “Safety Remove Hardware” This icon also appears when you attach a device that incorporates memory, for example a digital camera

The safety remove hardware option appears because if you disconnect the drive when data is being written or read from the drive, there is a strong possibility that the data on the drive can get corrupted .On the other hand, if the device was not in use when you disconnected it, your data could be intact. Window XP is equipped write caching for removable drives that are disabled by default, thereby reducing the possibility of data corruption. However, other versions of Windows like 2000 or 98, this remains enabled by default. This can slow down the reading or writing from and external drive. To check if write caching is disabled on your drive, follow these steps

• Connect your drive to your computer ,open ”my computer”, right click on the external drive ,and select ‘properties’
• Under the drive’ properties ,select the “hardware” tab, and select the drive again under “All Disk Drives” and select properties
• In the drive properties dialog box, select the “policies” tab and select the

• “Optimize for quick removal option.

Also it’s possible that using a high-speed or USB 1.1 port can slow down the performance of the drive

It is a good practice to use the “Safety Remove Hardware” option whenever possible

It is still recommended that you do so to ensure that the writing or reading from the device has been completed. It is reasonably safe to pull it out, but there is still the possibility of date corruption if it’s not safely disconnected.

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