A DIP switch is a set of manual electric switches that are packaged in a group in a standard dual in-line package (DIP) (the whole package unit may also be referred to as a DIP switch in the singular). This type of switch is designed to be used on a printed circuit board along with other electronic components and is commonly used to customize the behavior of an electronic device for specific situations.

DIP switches are an alternative to jumper blocks. Their main advantages are that they are quicker to change and there are no parts to lose.

[edit] DIP switch types

There are many different kinds of DIP switches. Some of the most common are the rotary, slide, and rocker types.

Rotary DIP switches contain multiple contacts, one of which is selected by rotating the switch to align it with a number printed on the package.

The slide and rocker types, which are very common, are arrays of simple SPST (single-pole, single-throw) contacts, which can be either on or off. This allows each switch to select a one-bit binary value. The values of all switches in the DIP package can also be interpreted as one number. For example, seven switches offer 128 combinations, allowing them to select a standard ASCII character. Eight switches offer 256 combinations, which is equivalent to one byte.

The DIP switch package also has socket pins or mounting leads to provide an electrical path from the switch contacts to the circuit board. Although circuits can use the electrical contacts directly, it is more common to convert them into high and low signals. In this case the circuit board also needs interface circuitry for the DIP switch, consisting of a series of pull-up or pull-down resistors, a buffer, decode logic, and other components.^[1] Typically the device's firmware reads the DIP switches when the device is powered on.

[edit] Applications

DIP switches were extensively used in older ISA PC cards to select IRQs and memory addresses. They were also often used on arcade games in the 1980s and early 1990s to store settings, before the advent of cheaper, battery-backed RAM and were very commonly used to set security codes on garage door openers as well as on some early cordless phones. This design, which used up to twelve switches in a group, was used to avoid interference from other nearby door opener remotes or other devices. Current garage door openers use rolling code systems for better security.

These type of switches were used on early video cards for early computers to facilitate compatibility with other video standards. For example, CGA cards allowed for MDA compatibility.

Recently (since the late 1990s), DIP switches have become less common in consumer electronics. Reasons include the trend toward smaller products, the demand for easier configuration through setting screens, and the falling price of non-volatile memory. But DIP switches are still widely used in industrial equipment because they are inexpensive and easy to incorporate into circuit designs, and because they allow settings to be checked at a glance without powering the system on.^{[citation needed]}

[edit] Notes