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Keyboard design adaptation



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Point-of-sale (POS, or EPOS: electronic point-of-sale) refers to equipment on the counter or desk of a cashier or clerk used for recording sales. Point-of-sale equipment varies from simple cash registers that record only transaction values all the way up to both generic and fully-custom alphanumeric keyboards. Point-of-sale keyboards often use a matrix (regular grid) key layout with complete flexibility of key assignment. Consequently, keycap sizes tend to be 1×1, 1×2, 2×1 and 2×2; larger keys occupy two and four switches and can consequently be very stiff. Combination designs exist that are partially conventional staggered layout and partially matrix layout. Keycaps are frequently “relegendable”: rather than factory-defined permanent legends, the legends are printed or written on paper labels and placed under clear covers that clip onto special flat-surface keycaps.

Cherry MX linear switches (“Cherry MX Black”) are a popular choice with POS keyboard manufacturers.

Point-of-sale keyboard manufacturers past and present include:

Although not intended for use for conventional office and home use, they do sometimes find favour for this purpose due to a preference for a matrix layout or for their configurability and (in some cases) high key count. Each manufacturer provides their own software for defining key functions; these programs can be notorious for their dependence on ageing requirements such as obsolete versions of Microsoft Windows or a 32-bit operating system. The benefit of freeform layout flexibility offered by these devices to enthusiasts is partially offset by the difficulty of resetting and reassigning the programming, especially with second-hand units of considerable age.




Specific examples

IBM TrackWrite

IBM TrackWrite—the ThinkPad “Butterfly” keyboard—is a clever design to allow the keyboard of a laptop computer to be wider than the keyboard itself. The keyboard is formed from two sections that slide relative to each other as the lid of the laptop opens. The two sides of the keyboard are positioned next to each other when the laptop lid is opened, and the keyboard assembly overhangs the sides of the laptop body. As the lid is closed, the right-hand section slides backwards so that the two sides can move closer together. This design is covered in US patents 5543787 “Keyboard with translating sections” (filed in March 1994) and 5659307 “Keyboard with biased movable keyboard sections” (filed in March 1995).