Jumper (computing)

A jumper being used in a base plate.

In electronics and in particular in computing, a jumper is an element that allows closing the electrical circuit of which two connections are a part. This can be done by soldering (enough tin is melted to close the circuit), by soldering a wire or cable between the two points, or most often by connecting two pins in a row or parallel using a piece of plastic that protects the conductive material that closes the circuit. circuit. The most common have sizes of 2.54 mm, 2 mm and 1.27 mm.

Opening or closing one of these jumpers enables or disables device features. This can also be done via a DIP switch, but it is bulkier and more expensive. Being its most common use to configure a motherboard or one of its peripherals or expansion cards, the optimization and concentration of circuitry in chipsets have made one of its most common uses in x86 PCs, determining the clock frequencies of different elements. The microprocessor can now be done electronically by changing settings in the BIOS or in utility programs.

Jumpers are still up to now a quick way of configuring hardware by applying the manufacturer's features. This makes it possible to manufacture devices that are suitable for different purposes with ease, even for an inexperienced user. But they are often used for functions that will not be changed frequently, such as setting the SCSI ID of an internal hard drive, or defining the device as master, slave, or cable select an IDE device (hard drive, optical drive, Zip drive...)

On old floppy drives, which had different behaviors and settings depending on the computer they were connected to (eg drive letter/identifier, 40 or 80 tracks, special modes only supported by the Commodore Amiga, etc...) it was very common to see rows of pins with jumpers and silk-screened next to each pair of pins, enigmatic initials only known to support technicians. The advent of high density (HD) drives and the triumph of the IBM PC compatible made these jumpers disappear, although some HD drives automatically supported those configurations (for example some Olivetti 286/386 compatible HD drives could be plugged directly into a Commodore Amiga supporting all its special formats and the high density of the PC) due to the integration of discrete components.

The main difficulty when doing the configuration is the information from the device manufacturer, which in some cases is only in the operation manual of the device or sometimes, with its respective legend printed on the printed circuit board where it is located. mounted the jumper.

Another of its frequent uses has been on sound cards and graphics cards to set the emulated mode at boot time.