IBM PC keyboard

The keyboard for IBM PC-compatible computers is standardized. However, during the more than 30 years of PC architecture being frequently updated, many keyboard layout variations have been developed.
A well-known class of IBM PC keyboards is the Model M. Introduced in 1984 and manufactured by IBM, Lexmark, Maxi-Switch and Unicomp, the vast majority of Model M keyboards feature a buckling spring key design and many have fully swappable keycaps.
Keyboard layouts.
The PC keyboard changed over the years, often at the launch of new IBM PC versions.
Common additions to the standard layouts include additional power management keys, volume controls, media player controls, and miscellaneous user-configurable shortcuts for email client, World Wide Web browser, etc.
The IBM PC layout, particularly the Model M, has been extremely influential, and today most keyboards use some variant of it. This has caused problems for applications developed with alternative layouts, which require keys that are in awkward positions on the Model M layout – often requiring the pinkie to operate – and thus require remapping for comfortable use. One notable example is the escape key, used by the vi editor: on the ADM-3A terminal this was located where the Tab key is on the IBM PC, but on the IBM PC the Escape key is in the corner; this is typically solved by remapping Caps Lock to Escape. Another example is the Emacs editor, which makes extensive use of modifier keys, and uses the Control key more than the meta key (IBM PC instead has the Alt key) – these date to the Knight keyboard, which had the Control key on the "inside" of the Meta key, opposite to the Model M, where it is on the "outside" of the Alt key; and to the space-cadet keyboard, where the four bucky bit keys (Control, Meta, Super, Hyper) are in a row, allowing easy chording to press several, unlike on the Model M layout. This results in the "Emacs pinky" problem.
Reception.
Although "PC Magazine" praised most aspects of the 1981 IBM PC keyboard's hardware design, it questioned "how IBM, that ultimate pro of keyboard manufacture, could put the left-hand shift key at the awkward reach they did". The magazine reported in 1982 that it received more letters to its "Wish List" column asking for the ability to determine the status of the three lock keys than on any other topic. "Byte" columnist Jerry Pournelle described the keyboard as "infuriatingly excellent". He praised its feel but complained that the Shift and other keys' locations were "enough to make a saint weep", and denounced the trend of PC compatible computers to emulate the layout but not the feel. He reported that the layout "nearly drove" science-fiction editor Jim Baen "crazy", and that "many of [Baen's] authors refused to work with that keyboard" so could not submit manuscripts in a compatible format. The magazine's official review was more sanguine. It praised the keyboard as "bar none, the best ... on any microcomputer" and described the unusual Shift key locations as "minor [problems] compared to some of the gigantic mistakes made on almost every other microcomputer keyboard".
"I wasn't thrilled with the placement of [the left Shift and Return] keys, either", IBM's Don Estridge stated in 1983. He defended the layout, however, stating that "every place you pick to put them is not a good place for somebody ... there's no consensus", and claimed that "if we were to change it now we would be in hot water".
Standard key meanings.
The PC keyboard with its various keys has a long history of evolution reaching back to teletypewriters. In addition to the 'old' standard keys, the PC keyboard has accumulated several special keys over the years. Some of the additions have been inspired by the opportunity or requirement for improving user productivity with general office application software, while other slightly more general keyboard additions have become the factory standards after being introduced by certain operating system or GUI software vendors such as Microsoft.