AT layout
Provided by the ASK Keyboard Dictionary
The AT layout refers to the key arrangement of Model F-based IBM 5170 Personal Computer AT Keyboard from 1984 that was briefly a de facto standard for PC keyboards in the mid-1980s. The AT's layout is a rework of the "XT layout" that eliminated many of the stepped keys, switched to a "backwards-L" enter key, and introduced a separation between the alphanumeric and numeric keypad sections. PC clone manufacturers and other companies briefly adopted the layout, but it was quickly overshadowed by the arrival of the Enhanced layout the following year. The "AT" name is derived from the IBM 5170 Personal Computer AT to retrospectively distinguish it from the XT layout.
