An overlay keyboard can do double duty. Its ability to hold configurations for two programs can double its usefulness.

Each of the keys on an overlay keyboard allows for the reproduction of any series of characters available on a regular keyboard. Also a sequence of letters, numbers, or functions may be obtained by pressing a single key. This is achieved by creating a configuration file corresponding to the user’s needs. This file is then transferred to the overlay keyboards permanent memory. The new key functions are then represented graphically on an overlay sheet.

Any program can be made more user-friendly with the addition of an overlay keyboard. However, during the course of a day we will use different programs. As a result the configuration for one program may not work well with a second program. Normally this would mean having to stop and reconfigure the keyboard.

A quality overlay keyboard will contain two separate configurations. Then by simply pressing the appropriate control keys the user can switch between the two configurations. The user would then quickly change the graphic overlay and the switch would be complete.

For example, one configuration could contain the short cut keys for a word processor and the second could be configured for a photo editing program.

When two different configurations are used some things need to be considered.

First, place similar commands on the same key. All programs use the Copy, Cut and Paste functions. Other commands include Open, Select All and Save. Keep these and other parallel commands on the same keys in the two templates.

Second, when creating an overlay use the same graphic to represent the command. If a word is used to describe the command use the same word. If a graphic such as an arrow is used use the same graphic. Use the same color scheme for the graphic on the two overlays. These simple tips will keep confusion to a minimum.

Source by Philip Kidder