There are myriad styles of keyboards for desktop PCs: wired and wireless, extra media keys, built-in trackballs, ergonomic split keyboards, spill-resistant and industrial rated. Ranging in price from USD $10 to $150, and although the keys are imprinted with Windows/PC nomenclature, PC keyboards also work on the Mac. A Keyboard Comedy There have been four standard keyboard layouts for PCs since the IBM PC in 1981, and each keyboard rearranged commonly used keys, drawing criticism to this day. For example, the Control key, used extensively in word processing, was originally easy to reach, only to be moved later to an awkward location (see Control key). PC -> AT -> Enhanced -> Windows The undersized Enter and left Shift keys on the original PC keyboard were corrected with IBM's AT PC, but the AT keyboard had a smaller Backspace key (see PC/XT keyboard and AT keyboard). The subsequent Enhanced keyboard fixed the Backspace key but relocated Control, Alt and function keys (see Enhanced keyboard). The Enhanced keyboard was superseded by the Windows keyboard, which did not correct anything but added special keys for Windows. Most all desktop PC keyboards today use this last layout (see Windows keyboard). Regardless of key size and placement, users always loved the feel of genuine IBM keyboards, which was carried over to high-end Lenovo models (see Lenovo). There is a difference (see premium keyboard). From DIN to USB PC keyboards connected via 5-pin and 6-pin DIN plugs, which were all replaced by USB. During the transition years, keyboards purchased separately came with USB-to-DIN adapters to plug into the DIN ports of existing computers. See legacy port and DIN connector. For all the keyboard entries in this encyclopedia, see keyboard.