IBM PC keyboard
| Industry | Computer hardware |
|---|---|
| Founded | August 1981 |
| Products | Keyboards (Model F, Model M, various layouts) |
The keyboard design for IBM PC-compatible machines has become standardized over time, although numerous keyboard layout variants have appeared throughout more than three decades of PC hardware evolution.
A prominent series within IBM PC keyboards is the Model M, which debuted in 1984 and was manufactured by companies including IBM, Lexmark, Maxi-Switch, and Unicomp. Most Model M models utilize a distinctive buckling spring mechanism for their keys and typically feature fully removable keycaps.
Keyboard layouts
As new IBM PC models were introduced, the PC keyboard underwent several modifications.
| Name | Keys | Description | Image | |
|---|---|---|---|---|
| Model F (PC/XT) | 83 | Featured the original function key column on the left side (F1–F10); electrically incompatible with PC/AT keyboards | Released August 1981. | |
| Model F (PC/AT) | 84 | Incorporated a Template:Key press key; numeric keypad separated; included indicator LEDs for Caps Lock, Scroll Lock, and Num Lock | Released August 1984. | |
| Model M (Enhanced) | Introduced navigation and control keys; dedicated inverted-T arrow cluster placed to the left of the numeric keypad; twelve function keys arranged in groups of four along the top row. Earlier versions (e.g., by Northgate Ltd.) positioned function keys in two columns on the left but were later replaced by the top-row format. PS/2 version launched April 1987. Variants include: | |||
| 101 | US standard configuration
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Released April 1986. | ||
| 102 | European configurations
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Released April 1986. | ||
| 103 | Korean layout
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| 104 | Brazilian ABNT NBR 10346 variant 2 and NBR 10347 numeric keypad layout
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| 106 | Japanese JIS layout
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| Windows[1] | Added two Windows keys plus a Menu key positioned left of the right Control key. First introduced with the Microsoft Natural keyboard designed for Windows 95. This layout is now common on most contemporary PCs regardless of operating system.[2] Regional variants are available: | |||
| 104 | US standard layout matching above | |||
| 105 | European layouts as described above | |||
| 106 | Korean layout as previously noted | |||
| 107 | Brazilian ABNT NBR variants as mentioned earlier | |||
Typical additions include keys for power management, volume adjustment, media playback controls such as Play/Pause, and customizable shortcuts for email or web navigation.
The IBM PC keyboard arrangement—particularly that of the Model M—has had a significant impact, with most modern keyboards adopting some form of its layout. This widespread adoption poses difficulties for software designed around alternative layouts that require less conventional finger positioning—often involving extensive use of the pinkie finger—thus necessitating remapping to improve ergonomics.[3] For instance, unlike the ADM-3A terminal where the Escape key was placed near Tab, on IBM PCs it occupies the corner position and is frequently reassigned to Caps Lock for user convenience.[3] The Emacs text editor relies heavily on modifier keys and favors Control over Alt (Meta), a usage pattern inherited from earlier keyboards such as the Knight and space-cadet models that facilitated easier chorded inputs compared to the Model M layout. This discrepancy has contributed to ergonomic concerns commonly referred to as "Emacs pinky."Cite error: The opening <ref> tag is malformed or has a bad name
Reception
PC Magazine commended most elements of the 1981 IBM PC keyboard's hardware design, though it raised concerns about "how IBM, a leader in keyboard manufacturing, positioned the left-hand Shift key in such an awkward location." In 1982, the publication noted that it received more correspondence about the desire to monitor the status of the three lock keys than any other subject. Byte columnist Jerry Pournelle characterized the keyboard as "frustratingly excellent," applauding its tactile response but expressing dissatisfaction with the placement of the Shift and several other keys. He also observed that while many PC compatible machines replicated the key arrangement, they failed to duplicate its feel. Pournelle mentioned that the layout "nearly drove" science-fiction editor Jim Baen "to frustration," with some writers refusing to use that keyboard, thereby restricting manuscript submissions in compatible formats. Nonetheless, Byte's formal review was more favorable, labeling it "unquestionably the best ... on any microcomputer" and considering the unusual Shift key positions minor flaws compared to more significant errors found on other microcomputer keyboards.
IBM's Don Estridge admitted in 1983 that he was not entirely satisfied with the locations of the left Shift and Return keys but defended the overall design, explaining that "any position chosen will be inconvenient for someone ... no consensus exists," and cautioned that altering it at that stage would create considerable complications.
Standard key meanings
The PC keyboard traces its origins to teleprinters, blending conventional and specialized keys to boost efficiency in office productivity software. Numerous keys became standardized after being adopted by prominent operating system and graphical user interface developers such as Microsoft.
From mechanical typewriters
- enables uppercase letters or the upper character; initially, it mechanically shifted typewriter components to print capital letters.
- locks uppercase input; pressing Shift reverses this effect. It served as a mechanical lock for the Shift function.
- advances to the following line or triggers the default action; typewriters utilized a carriage return lever.
- inserts a tab character, moving the cursor forward to the next tab stop.
From Teletype keyboards
- transforms letters and digits into ASCII control codes, facilitating commands like CTRL-S (pause output) and CTRL-Q (resume output).
- produces an ASCII escape character, frequently used to exit menus or modes.
- signifies the tilde accent; currently often employed for logical negation or approximation.
- represents the backtick or grave accent, historically used for non-English diacritics; occasionally serves as an opening quotation mark.
- denotes a circumflex accent or exponentiation when superscript is unavailable.
- corresponds to an asterisk, commonly used for annotations or multiplication.
- stands for an underscore, utilized in programming to substitute spaces within compound identifiers.
- is a vertical bar ("pipe"), originally a typographic divider and extensively used in Unix shells for command piping.
Invented for computers with video displays
- Function keys (F1–F12) serve different purposes depending on the application; they frequently open Help menus.
- Cursor keys (, , , ) move the cursor around; when combined with Shift, they enable item selection.
- moves the cursor to the beginning of the text.
- moves the cursor to the line’s end.
- and navigate through documents by pages.
- removes the character following the cursor or deletes selected content.
- switches between insert and overwrite modes; when used with Ctrl and Shift, it supports copy () and paste () shortcuts in line with IBM CUA standards—still favored by some PC users for ergonomic advantages.
- initially printed screen content; currently, captures screenshots. Pressing Alt modifies its function to SysRq.
- toggles the numeric keypad between numeric input and navigation; user preferences vary and can often be configured in BIOS settings.
- is infrequently utilized but can lock scrolling in programs like Microsoft Excel, freeze console output, or toggle devices on certain KVM switches.
- halts processing; combined with Ctrl, it pauses programs in DOS or debuggers, while with the Windows key, it opens System Properties.
- accesses extended characters via numeric keypad codes.
- opens the Start menu in Microsoft Windows and facilitates desktop shortcuts; on Mac keyboards, it functions as the Command key.
- launches the context menu of the active application, functioning similarly to a right-click.
- , introduced on January 4, 2024, replaces the Menu key to activate Microsoft Copilot in Windows by entering .
- generates special characters on non-English keyboards and is often emulated by .
- , commonly found on laptops, enables secondary functions such as numeric keypad emulation or hardware controls (e.g., brightness, volume), indicated by color-coded symbols matching the Fn key’s hue.
- , located near the right Shift key on some keyboards, adjusts key repeat rates when combined with function keys.
Connection
| System | Connector | Image | Pinout | Transmission Protocol | Command Strings |
|---|---|---|---|---|---|
| PC (Type 1) | 5-pin DIN (DIN 41524) |
1 CLK 2 DATA |
2 start bits, 8 data bits, make/break bit (keydown/keyup), 1 stop bit keyboard reset by grounding pin 3 |
Not supported | |
| XT (Type 2) | 1 CLK 2 DATA |
2 start bits, 8 data bits, make/break bit (keydown/keyup), 1 stop bit keyboard reset via specific DATA and CLK sequence | |||
| AT | 1 CLK 2 DATA |
1 start bit, 8 data bits, 1 odd parity bit, 1 stop bit keyboard reset through command string |
Supported | ||
| PS/2 "PS/2 port" |
6-pin Mini-DIN (DIN 45322) |
1 DATA 2 N/C (or MOUSE DATA) | |||
| Later PC compatibles |
4-pin USB Type A connector |
1 +5V 2 Data − |
sync field followed by 8-bit bytes sent as packets (HANDSHAKE, TOKEN, DATA, Special packets), least-significant bit first. |