Pairs of devices may establish a trusted relationship by learning (by user input) a shared secret known as a "passkey". A device that wants to communicate only with a trusted device can cryptographically authenticate the identity of the other device. Trusted devices may also encrypt the data that they exchange over the air so that no one can listen in. The encryption can however be turned off and passkeys are stored on the device's file system and not the Bluetooth chip itself. Since the Bluetooth address is permanent a pairing will be preserved even if the Bluetooth name is changed. Pairs can be deleted at any time by either device. Devices will generally require pairing or will prompt the owner before it allows a remote device to use any or most of its services. Some devices such as Sony Ericsson phones will usually accept OBEX business cards and notes without any pairing or prompts. Certain printers and access points will allow any device to use its services by default much like unsecured Wi-Fi networks.

1.Wireless control of and communication between a cell phone and a hands free headset or car kit. This is the most popular use. 2.Wireless networking between PCs in a confined space and where little bandwidth is required. 3.Wireless communications with PC input devices such as mouses and keyboards and output devices such as printers. 4. Transfer of files between devices via OBEX. 5.Transfer of contact details, calendar appointments, and reminders between devices via OBEX. 6.Replacement of traditional wired serial communications in test equipment, GPS receivers and medical equipment. 7.For remote controls where infrared was traditionally used. 8.Sending small advertisements from Bluetooth enabled advertising hoardings to other, discoverable, Bluetooth devices. 9.Sending small advertisements from Bluetooth enabled advertising hoardings to other, discoverable, Bluetooth devices. 10.Wireless control of a games console, Nintendo's Wii and Sony's PlayStation 3 will both use Bluetooth technology for their wireless controllers. 11.ending commands and software to the upcoming LEGO Mindstorms NXT instead of infra red.

When troubleshooting a remote printer, check to see whether the printer is connected to the system through a print-sharing device. If so, connect the printer directly to the system, and try it. It is not good practice to use laser printers with these types of devices. A better arrangement is to install, or just use, an LPT2 port to attach an additional printer to the system. Beyond two printers, it would be better to use network-capable printers. 

Use a vacuum cleaner to remove dust buildup and excess toner from the interior of the laser printer. Clean the laser printer's rollers using a damp cloth or denatured alcohol.

Laser printers can be a source of electrocution, eye damage (from the laser), and burns (from the fuser assembly). The laser printer tends to have several high-voltage and high-temperature hazards inside it. To get the laser printer into a position in which you can observe its operation, it will be necessary to defeat some interlock sensors. This action will place you in potential contact with the high-voltage, high-temperature areas in the printer. Take great care when working inside the laser printer.

When the print becomes noticeably faint, the cartridge should be replaced. Most dot-matrix printers use a snap-in ribbon cartridge. To replace a typical ribbon cartridge, move the print head carriage assembly to the center of the printer. Remove the old cartridge by freeing it from its clips, or holders, and then lifting it out of the printer. Tighten the ribbon tension by advancing the tension knob on the cartridge in a counterclockwise direction until the ribbon is taut. Snap the cartridge into place, making certain that the ribbon slides between the printhead and the ribbon mask. Slide the printhead assembly back and forth on the rod to check for proper ribbon movement.